Can a faulty immobilizer make the engine backfire into the air intake. The car starts and ticks over nicely, but as soon as it warms up all hell lets loose when i press the throttle. So far i have fitted new plugs and coils, new fuel pump, new fuel filter, new cold start temp sensor, new Maf sensor, also i have had the Catalytic Converter tested. I give up, please help. Rob.
Rob it sounds like a bad dose of pre ignition i.e. the plugs firing before the valves have closed (too early not circa 7 degrees or so after TDC).
Looking back at your posts you’ve had the miseries since switching the ECU does the one you are now using mirror the original re. Part #, and all the Suffixes as that unit determines the firing point along with the CKPS? If the Firmware mapped into RAM is incorrect that could be the cause, as I’ve not heard of a X300 loosing the valve timing.
Another thought if your car has a sunroof check the connectors on the ECU for corrosion as that has caused members misfiring issues and the culprit is usually blocked drains causing water to run down the A post onto the ECU.
Thank you for getting back to me Neil. The earlier posts were about a different car, although i really love the X300 i don’t seem to have a lot of luck with them.
We have checked the ECU and its dry and no loose connections. Are you saying the culprit could be the CKPS faulty, or are you saying the ECU could be faulty. Rob.
http://jimbutterworth.co.uk/8engine.htmMy gut feeling is that there is a timing error causing pre ignition and the ECU/ CKPS or both could be causing it also the set up of the relationship between the Camshaft and the Crankshaft as well as the Notched ring that is on the Crankshaft and provides the timing pulses to the ECU on hence the coils, they all have to sit within a narrow opperating window!
If you check out Jim Butterworth’s site here: http://jimbutterworth.co.uk/8engine.htm
There is quite a bit of good info also there is much on:
www.jagrepair.com
Take a look there too.
A Scanner with live data (the Bluetooth type that plugs into the OBD II Diagnostic port should clearly indicate where the firing point is occuring, can’t remember what it typically is but hopefully Bob or the like will chip in.
My advice is keep it simple and cheap by checking the easy things first if you can’t steal or borrow a scanner an Ebay dongle with Torque or Wallmart for $12.77
Thank you very much for all your help Neil, i will let you know how i get on
Rob, it could also be theTPS being faulty see Jim’s write up.
FWIW 7 degrees after TDC comes to mind as nominal but IIRC mine idles at 17 degrees with an Andy Bracket fitted to th CKPS. I’ll try and remember to fire up the scanner and check, if I can change the mobile monitor from being the revesing camera back to a data scanner.
I’m suprised that Bob or someone hasn’t asked what if any Codes you are pulling, so I will.
Hi Neil, there is a guy coming mid week to plug the car in for me, hopefully it might pinpoint the fault for me. I don’t know how accurate they are. Up to now it has not been on a scanner, so I’m crossing my fingers. Rob.
Hi again Rob, checked my Timing Adv. today it’s +10 Nom. +19.5 @ 800 rpm peaking at +40 from 3000 rpm to Red Line.
As I said it’s a 3.2 Sport and it has the Andy Stodart bracket fitted giving IIRC about a 7 degree advance on the ECU Mapping.
Good luck
Finally got back to basics where the starting point was TDC and everything was lined up to fire the plugs at a given point in ADVANCE of that, usually arrived at by trial and error using feelers, vacuum gauges and timed road tests!
Now it’s all predetermined and built in by the design team. But as you are finding “Sod’s Law” can often still prevail.
Well i finally got it plugged in and it showed fault code P0413 Secondary Air Injection System Switching Valve ‘A’ Circuit Open Could somebody please tell me where to find this on the engine. Thank you. Rob.
Hi Rob take a look here:
Secondary Air Injection System – P0413
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0413 will most likely be set due to an air switching valve in an open circuit.
Remedy:
Switch off engine.
Check the pump and relay harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 7 of the test below.
Disconnect the AIR harness and relay if no fault is found and go to step 1 of the test below.
Test:
Check the air pump relay operation. If it gives a positive result then disconnect the pump and go to step 2. If it is faulty then replace the relay, re-connect the harness and go to step 7.
Check the harness continuity RS 006/004 is correctly wired to PI 061/013. If this gives a positive result then go to step 3. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 061/013 is correctly wired to PI 146/003. If this gives a positive result then go to step 4. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 146/005 is correctly wired to PI 115/001. If this gives a positive result then go to step 5. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 146/005 is correctly wired to PI 115/002. If this gives a positive result then go to step 6. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 115/003 is correctly wired to PI 104/007. If this gives a positive result then fit a new AIR relay, re-connect the harness and go to step 7. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 8.
Repeat the diagnostic procedure. If this now omits a positive
Catalyst System Efficiency – P0420
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0420 will most likely be set due to a catalyst efficiency low in the A Bank.
Remedy:
Ensure there are no exhaust leaks. If so repair or replace pipe work and go to step 11 of the test below.
Ensure there are no inlet air leaks. If so repair or replace pipe work and go to step 11 of the test below.
Disconnect both upstream H02S sensors if no fault is found, and go to step 1 of the test below.
Test:
Check the harness continuity PI 128/001 is correctly wired to PI 105/008. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness continuity PI 128/002 is correctly wired to PI 105/006. If this gives a positive result then go to step 3. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/001 will complete a circuit to PI 105/008. If this gives a positive result then go to step 4. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/002 will complete a circuit to PI 105/019. If this gives a positive result then go to step 5. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 128/002 will complete a circuit to ground. If it reads 0V then fit a new AIR relay, re-connect the harness and go to step 6. If there is a full or partial short circuit then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/002 will complete a circuit to ground. If it reads 0V then fit a new AIR relay, re-connect the harness and go to step 7. If there is a full or partial short circuit then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 128/001 will complete a circuit to RS 006/008. If this gives a positive result then go to step 8. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 128/002 will complete a circuit to RS 006/008. If this gives a positive result then go to step 9. If the circuit is shorts then find and fix the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/001 will complete a circuit to RS 006/008. If this gives a positive result then go to step 10. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness continuity PI 129/002 is correctly wired to RS 006/008. If this gives a positive result then replace new upstream H02S sensors and catalyst, re-connect the harness and go to step 11. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result, then stop. If the fault is still present then go to step 12.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Catalyst System Efficiency – P0430
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0430 will most likely be set due to a catalyst efficiency low in the B Bank.
Remedy:
Ensure there are no exhaust leaks. If so repair or replace pipe work and go to step 11 of the test below.
Ensure there are no inlet air leaks. If so repair or replace pipe work and go to step 11 of the test below.
Disconnect both upstream H02S sensors if no fault is found, and go to step 1 of the test below.
Test:
Check the harness continuity PI 128/001 is correctly wired to PI 105/008. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness continuity PI 128/002 is correctly wired to PI 105/006. If this gives a positive result then go to step 3. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/001 will complete a circuit to PI 105/008. If this gives a positive result then go to step 4. If the circuit experiences a full or partial short circuit then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/002 will complete a circuit to PI 105/019. If this gives a positive result then go to step 5. If the circuit experiences a full or partial short circuit then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 128/002 will complete a circuit to ground. If it reads 0V then go to step 6. If there is a full or partial short circuit then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/002 will complete a circuit to ground. If it reads 0V then go to step 7. If there is a full or partial short circuit then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 128/001 will complete a circuit to RS 006/008. If this gives a positive result then go to step 8. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 128/002 will complete a circuit to RS 006/008. If this gives a positive result then go to step 9. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness insulation PI 129/001 will complete a circuit to RS 006/008. If this gives a positive result then go to step 10. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Check the harness continuity PI 129/002 is correctly wired to RS 006/008. If this gives a positive result then fit new upstream H02S sensors and catalyst, and go to step 11. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 11.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result, then stop. If the fault is still present then go to step 12.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Evaporative Emission Control – P0441
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0441 will most likely be set due to an EVAP purge flow fault.
Remedy:
Complete test below.
Test:
Ensure there are no seizures or blockages in the purge valve. If not then go to step 2. If there are seizures or blockages then replace the purge valve and go to step 4.
Ensure there are no leaks in the pipe work. If not then go to step 3. If there are leaks then repair or replace and go to step 4.
Check to see if the pump is running continuously. If not then go to step 4. If so then repair or replace pump and go to step 4.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result, then stop. If the fault is still present then go to step 5.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Evaporative Emission Control – P0443
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0443 will most likely be set due to an EVAP purge control in the valve circuit fault.
Remedy:
Switch off engine.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 6 of the test below.
Disconnect the EVAP valve if no fault is found and go to step 1 of the test below.
Test:
Check the harness continuity PI 130/001 is correctly wired to PI 119/005. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness continuity PI 130/002 is correctly wired to PI 105/006. If this gives a positive result then go to step 3. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 130/001 will complete a circuit to ground. If this gives a positive result then go to step 4. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 130/002 will complete a circuit to ground. If this gives a positive result then go to step 5. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 130/001 will complete a circuit to PI 130/002. If this gives a positive result then go to step 6. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 7.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Vehicle Speed Sensor – P0500
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0500 will most likely be set due to a Vehicle Speed Sensor fault.
Remedy:
Disconnect Vehicle Speed Sensor and go to step 1 of the test below.
Test:
Check harness continuity PI 105/028 is correctly wired to FC 010/003. If this gives a positive result go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 3.
Check the Vehicle Speed Sensor signal from ECM. If this gives a positive result then go to step 3. If it is faulty then replace the sensor, re-connect the harness and go to step 3.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 4.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Idle Speed Control – P0506
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0506 will most likely be set due to an Idle Speed Control RPM low fault.
Remedy:
Complete test below.
Test:
Ensure there are no blockages in valve drillings. If not then go to step 2. If the valve drillings are blocked then repair or replace the valve and go to step 6.
Ensure there are no seizures in the stepper motor. If not then go to step 3. If the stepper motor is faulty then repair or replace and go to step 6.
Ensure the valve is fitted correctly. If this gives a positive result then go to step 4. If it is incorrect then repair or replace the valve and go to step 6.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are in good condition then go to step 5. If they are faulty then repair or replace and go to step 6.
Start the engine and run at idle speed, monitor Pid 10 ensuring the value changes with throttle position. If this gives a positive result then go to step 6. If it is incorrect then replace the throttle potentiometer and go to step 6.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop.
Idle Speed Control – P0507
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0507 will most likely be set due to an Idle Speed Control RPM high fault.
Remedy:
Complete test below.
Test:
Ensure the base idle setting is correct. If it is then go to step 2. If it is incorrect then reset and go to step 7.
Ensure there are no blockages in the valve drillings. If there are no blockages then go to step 3. If there are blockages then repair or replace the valve and go to step 7.
Ensure there are no seizures in the stepper motor. If not then go to step 4. If the stepper motor is faulty then repair or replace and go to step 7.
Ensure the valve is fitted correctly. If so then go to step 5. If the valve is not fitted correctly then repair or replace and go to step 7.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are in good condition then go to step 6. If they are faulty then repair or replace and go to step 7.
Start the engine and run at idle speed, monitor Pid 10 ensuring the value changes with throttle position. If this gives a positive result then go to step 7. If it is incorrect then replace the throttle potentiometer and go to step 7.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop.
Idle Speed Control – P1508
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1508 will most likely be set due to an Idle Speed Control open circuit fault.
Remedy:
Switch off engine.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 7 of the test below.
Disconnect the Idle Speed Control if no fault is found and go to step 1 of the test below.
Test:
Check the harness continuity PI 113/001 is correctly wired to PI 104/003. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 113/002 is correctly wired to PI 104/016. If this gives a positive result then go to step 3. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 113/003 is correctly wired to PI 104/028. If this gives a positive result then go to step 4. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Check the harness continuity PI 113/004 is correctly wired to PI 104/029. If this gives a positive result then go to step 5. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
Ensure the resistance between Idle Speed Control pin 1 to Idle Speed Control pin 002 is within 40 – 60 Ohms. If it is within the limits then go to step 6. If it is out of range replace the Idle Speed Control, re-connect the harness and go to step 7.
Check the harness insulation Idle Speed Control pin 3 to Idle Speed Control pin 4. If this gives a positive result then go to step 7. If the reading is out of range then replace the Idle Speed Control, re-connect the harness and go to step 7.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 8.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Idle Speed Control – P1509
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1509 will most likely be set due to an Idle Speed Control short circuit fault.
Remedy:
Switch off engine.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 12 of the test below.
Disconnect the Idle Speed Control if no fault is found and go to step 1 of the test below.
Test:
Check the harness insulation PI 113/001 will complete a circuit to PI 113/002. If this gives a positive result then go to step 2. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the harness insulation PI 113/001 will complete a circuit to PI 113/003. If this gives a positive result then go to step 3. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the harness insulation PI 113/001 will complete a circuit to PI 113/004. If this gives a positive result then go to step 4. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the harness insulation PI 113/002 will complete a circuit to PI 113/003. If this gives a positive result then go to step 5. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the harness insulation PI 113/002 will complete a circuit to PI 113/004. If this gives a positive result then go to step 6. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the insulation Idle Speed Control pin 1 will complete a circuit to Idle Speed Control pin 2. If this gives a positive result then go to step 7. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the insulation Idle Speed Control pin 1 will complete a circuit to Idle Speed Control pin 3. If this gives a positive result then go to step 8. If it short circuits then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the insulation Idle Speed Control pin 1 will complete a circuit to Idle Speed Control pin 4. If this gives a positive result then go to step 9. If it short circuits then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the insulation Idle Speed Control pin 2 will complete a circuit to Idle Speed Control pin 3. If this gives a positive result then go to step 10. If it short circuits then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the insulation Idle Speed Control pin 2 will complete a circuit to Idle Speed Control pin 4. If this gives a positive result then go to step 11. If it short circuits then find and repair the wiring fault, re-connect the harness and go to step 12.
Check the insulation Idle Speed Control pin 3 will complete a circuit to Idle Speed Control pin 4. If this gives a positive result then go to step 12. If it short circuits then find and repair the wiring fault, re-connect the harness and go to step 12.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 13.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Park/Neutral Switch – P1514
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1514 will most likely be set due to a PNPS high load neutral/ drive fault.
Remedy:
Select ‘D’ position and ensure the rotary switch illuminates on drive. If it is faulty then repair and go to step 6 of the test below.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 6 of the test below.
Complete test below if no fault is found.
Test:
Check the harness insulation CC 013/024 will complete a circuit to ground. If this gives a positive result then go to step 2. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 063/005 will complete a circuit to ground. If this gives a positive result then go to step 3. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 105/027 will complete a circuit to ground. If this gives a positive result then go to step 4. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation FC 002/020 will complete a circuit to ground/003. If this gives a positive result then go to step 5. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation FC 007/035 will complete a circuit to ground. If this gives a positive result then go to step 6. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 7.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Park/Neutral Switch – P1516
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1516 will most likely be set due to a gear change neutral/ drive fault.
Remedy:
Select ‘D’ position and ensure the rotary switch illuminates on drive. If it is faulty then repair and go to step 6 of the test below.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 6 of the test below.
Complete test below if no fault is found.
Test:
Check the harness insulation CC 013/024 will complete a circuit to ground. If this gives a positive result then go to step 2. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 063/005 will complete a circuit to ground. If this gives a positive result then go to step 3. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation PI 105/027 will complete a circuit to ground. If this gives a positive result then go to step 4. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation FC 002/020 will complete a circuit to ground/003. If this gives a positive result then go to step 5. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Check the harness insulation FC 007/035 will complete a circuit to ground. If this gives a positive result then go to step 6. If the circuit shorts then find and repair the wiring fault, re-connect the harness and go to step 6.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 7.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Park/Neutral Switch – P1517
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1517 will most likely be set due to a cranking neutral/ drive fault.
Remedy:
Select ‘N’ position and ensure the rotary switch illuminates on drive. If it is faulty then repair and go to step 8 of the test below.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 8 of the test below.
Complete test below if no fault is found.
Test:
Check the harness continuity CC 013/024 is correctly wired to PI 105/027. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 8.
Check the voltage level at CC 013/024. If this reads 12 Volts then switch on ignition and go to step 3. If it reads below 12V then find and repair the wiring fault, re-connect the harness and go to step 8.
Check the voltage level at CC 013/020 and 021. If this reads 0V then go to step 4. If it reads above 0V then find and repair the wiring fault, re-connect the harness and go to step 8.
Check the decoder inputs from the rotary switch. If this gives a positive result then go to step 5. If it is faulty then reset the rotary switch using tool JD 161 and go to step 8.
Check the harness continuity GB 002/002 is correctly wired to CC 013/013. If this gives a positive result then go to step 6. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 8.
Check the harness insulation GB 002/003 will complete a circuit to CC 013/011. If this gives a positive result then go to step 6. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 8.
Check harness continuity GB 002/004 is correctly wired to CC 013/012. If this gives a positive result then go to step 8. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 8.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 9.
Repeat the diagnostic procedure. If this now omits a positive result then stop.
Codes common to ECM and TCM – P0605
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P0605 will most likely be set due to an internal ROM test fault in the control module.
Remedy:
After running the service drive cycle, ensure the TCM is not in default mode. If the TCM is in default mode then repair.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace.
Ensure the TCM is working sufficiently. If not then replace the TCM.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle.
Repeat the diagnostic procedure if the fault is still present. If this now omits a positive result then stop.
Codes common to ECM and TCM – P1775
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1775 will most likely be set due to a MIL illumination request from TCM.
Remedy:
After running the service drive cycle, ensure the TCM is not in default mode. If the TCM is in default mode then repair.
Check the harness and connectors to ensure they are in good condition and are reliable. If they are faulty then either repair or replace.
Ensure the TCM is working sufficiently. If not then replace the TCM.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle.
Repeat the diagnostic procedure if the fault is still present. If this now omits a positive result then stop.
Codes common to ECM and TCM – P1776
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1776 will most likely be set due to a duration fault in the ignition retard.
Remedy:
In order to check the sport mode cannot be engaged, run the engine for 20 seconds. This will check if the TCM is in substitute function. If it is found to be faulty then repair and go to step 4 of the test below.
Check the harness and connectors (ECM and TCM) to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go step 4 of the test below.
If no fault is found then complete the test below.
Test:
Check the harness continuity PI 105/026 is correctly wired to CC 007/032. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 4.
Using an oscilloscope check the PWM signal is within 10 – 19% (1.1 – 2.1ms). If this gives a positive result then go to step 3. If it is out of range replace TCM and go to step 4.
Ensure there are no stored fault codes in the ECM. If this gives a positive result then go to step 4. If there are stored faults replace the ECM and go to step 4.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If the fault is still present then go to step 5.
Repeat the diagnostic procedure if the fault is still present. If this now omits a positive result then stop.
Codes common to ECM and TCM – P1777
Model:
Jaguar XJ Range 1996, 1997
Complaint:
Fault code P1777 will most likely be set due to a circuit fault in the ignition retard.
Remedy:
In order to check the sport mode cannot be engaged, run the engine for 20 seconds. This will check if the TCM is in substitute function. If it is found to be faulty then repair and go to step 4 of the test below.
Check the harness and connectors (ECM and TCM) to ensure they are in good condition and are reliable. If they are faulty then either repair or replace and go to step 4 of the test below.
If no fault is found then complete the test below.
Test:
Check the harness continuity PI 105/026 is correctly wired to CC 007/032. If this gives a positive result then go to step 2. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 4.
Using an oscilloscope check the PWM signal is within 10 – 19% (1.1 – 2.1ms). If this gives a positive result then go to step 3. If it is out of range replace TCM and go to step 4.
Ensure there are no stored fault codes in the ECM. If this gives a positive result then go to step 4. If there are stored faults replace the ECM and go to step 4.
Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If the fault is still present then go to step 5.
Repeat the diagnostic procedure if the fault is still present. If this now omits a positive result then stop.
For the whole thing:
http://www.bba-reman.com/gb/content/jaguar_xj_range_9697_engine_management_part2
Hi Neil, thank you very much for all that information. We have managed to stop the car backfiring into the air intake, it turned out to be the temperature sensor on the coolant. This has left us with the engine struggling to rev up properly when it gets warm. We have narrowed it down to one of three things, either faulty fuel injectors, EGR, valve or worse case scenario cracked cylinder head. We cant make out if the engine is not getting enough fuel,or is it choking up by something. Could you please point me in the right direction to find the EGR Valve, bit miffed where it is. Regards, Rob.
Some more poking around under the hood, turns out this hose is not part of the EGR, and I’m not sure if it even goes under the intake.
See the photo below with indicated hose. The EGR hoses are completely separate–those are up front and out in the open. This hose goes from the TB outlet then disappears under the intake. The FSM indicates it should go back to the water pump. I can not see where it’s going.
Is it possible this is serviceable by just removing the throttle body?
https://www.jaguarclassicparts.com/uk/jaguar-xj-x300-parts/engine-management-emission-systems/exhaust-gas-recirculation-system/egr-valve-and-pipes-4-0-litre-naturally-aspirated
We don’t have them fitted here in God’s own country! Thank goodness.
Hi Neil, I’m probably getting a bit impatient til the guy turns up on Wednesday with his diagnostics etc, but would a sticking engine valve give the similar symptoms when the the engine gets hot. Iv noticed that it does not backfire anymore and does not smoke as much as it did, not sure why. What it does do now is the revs go up and down when i press the throttle, it sounds like its searching for fuel, or choking its self. Rob.
Could be the ERG coked up I guess or perhaps the TPS. As Bob would say what do the DTC’s give?
Hi Neil. Sorry to be a pest, but i think you might be right about the TPS, iv been reading up on it. Where do i find it on the engine. Did you mean EGR in your last post, as i cant find any mention of the ERG. Rob.
Sorry EGR a typo! TPS is on the TB Jim’s AJ16 write up covers that, chapter & verse. A bad track will cause sticking of revs or sudden surges.
High Idle: from Mike Jones
Can be caused by a faulty Throttle Position sensor - quite possibly intermittent
OR can be caused by a faulty ISCV (Idle Speed Control Valve) - externally visible on outside of throttle body:
Idle speed OK (around 700 rpm) when running up to normal operating temperature (closed loop) but when taken for a run, idle speed increased to around 1600 rpm.
Checked throttle butterfly returning and not snagging or sticking. Checked inlet pipework post MAF for vacuum leaks but unable to fault.
Plugged in OBD2 via laptop (using Proscan). Noted that as soon as engine running in closed loop control MAF reading gradually increased from 0.05 to 0.07 (sorry can’t remember the units). This indicated to me that ISCV not stepping correctly.
Removed throttle body, then remove ISCV and the Throttle pot (very carefully!!). Throttle body surprisingly clean but gave it a good clean with cleaning spray. Sprayed Throttle Body pot with contact cleaner. Cleaned ISCV then checked the two coils. Both checked out OK at around 50 ohms.
Plugged ISCV in and keyed ignition on then off. Noted that ISCV piston motored in then out as it should do. Decided to re-assemble everything and refit.
Fired up the engine but fault still present and same symptoms.
I had a spare ISCV (ebay 99p) that I purchased about 5 years ago. Again removed TB then fitted replacement ISCV.
Re-assemble and fired up. Took car on a good run and all OK. Idle speed steady at 700 rpm (park). Have been using for several days now and no further problems.
Seems that original ISCV was faulty but not sure why.
Crank Sensor:
A new X300 crank sensor has a resistance of around 1,300 ohms and inductance of about 1 Henry. The Jaguar part number is LHE1640AA. If the sensor is working, the tachometer should jump up to about 200rpm or so when cranking but not firing.
On the bench, with the sensor connected to a peak-hold DVM, flicking a steel-bladed screwdriver back-and-forth across the magnetized ‘pip’ in the centre of the sensor’s face yielded peak voltages of around 250mV to 300mV depending on the speed at which the screwdriver moved.