Need your help… We are a family of three XJS models from 1-1994 and 2-1995. Recently my sons 1995 4.0 ZF4HP24 would not shift well into upper gears and then it completely stopped engaging when shifting from drive, reverse, neutral, etc… The car would not move or engage moving the shifter. Being a skilled DIY (or i thought) I decided to replace the transmission with a good warrantied tranny as had a shop quote of $4-6000.00. I found a low mileage used tranny and swapped the tranny in my driveway. So…
The new used transmission is in and hooked up full of fluid with new filter and the same results with the old transmission … with the addition my dumb ass not filling up the original the torque converter and evidently from the dripping oil, incorrectly installing the rear oil main to boot…uggg!
The car is idling fine but will not engage in drive (any gear), reverse, nada, no codes and no transmission light illuminated…
I have cleaned the tranny plug contacts, checked every fuse and relay in the car to no avail. I don’t even know where to begin… Obviously the old tranny is probably fine as well as the new and this is something electronic or both new and old tranny’s are bad… damint man
Any help and steps to diagnose would be very appreciated… TIA
Since the problem is the same with attempt of each transmission, I would be looking at any control circuits - have you check the transmission relay, located in the right rear wheel well area in the boot - go to www.jagrepair.com - then XJS electrical, 1995-1996 electrical, then look at figure 26 for explanation of location of connections and wiring schematic - Tex.
Thanks mate… I took the oil pump out of the old transmission this am and its fine… Someone mentioned the torque converter is bad. Any experience with the converter?? TIA
Does the gear selector actually register that different driving modes have been selected?
Firstly check all power and Gnd sources are sound, then you probably need an oscilloscope to check the Can signals are reaching the Tcm, but check the Can is physically sound using a resistance check, and voltage check on each Can wire.
Do you have diagnostic equipment that can command the Tcm to perform any functions, if so try to operate various modes and components using it.
Hello Chandler - if the internal vanes in the torque convertor are broken (dislodged) then the fluid pressure flow would not be there to provide use of the transmission - usually a lot of rattle noise will occur with vane damage - I do not think that this is your problem - wondering if the retainer, for the shift cable housing, may have come off - if it had, then you may not have noticed, so when you installed the replacement transmission, the cable would have still been in a “float” position and be affecting the ability to place the transmission in any gear - just a thought - Tex.
Tex. Shifter cable is secure and ive double checked the shift cable and links which a ppears normal. I also cleaned the on the electrical connections when installing the used tranny. There is zero movement in any gear forward or reverse…
Chandler - were you able to check the transmission control relay in the boot to verify operation and circuit flow - just trying to figure out what is the common factor with use of either transmission being non-operational - Tex.
I’ve had a quick look and can see this isn’t a Can controlled Tcu, so testing of individual signals is possible.
If the mechanical engagement is functioning then the issue has to be electrical (yeah, I know, obvious), so check power and Gnd to the Tcu followed by the mode and selector switch functions being seen at the Tcu.
If all inputs are correct and the transmission still won’t operate, I suspect either the Tcu isn’t seeing the engine revs input, or the pressure solenoid control is being interrupted.
You should be able to measure most of the signals with a test lamp, Led lamp, or voltmeter, but a cheap oscilloscope might be necessary for any speed related signals. ( A voltmeter should suffice for hall effect sensor outputs)
I’m a bit surprised the transmission can’t select a single forward, or reverse gear just by the mechanical control.
Tex… Thank you for all the help… As of now everyone is saying that with zero electronics hooked up or operational that we should have movement hydraulicly in reverse and gear1 with everything properly installed. If there is no hydraulic movement then its two possibilities… Bad oil pump or bad torque converter. I took the originbal tranny apart and inspected the oil pump and it appears perfect. I reused the original torque converter mated to the new used tranny (had no idea being my first solo swap that was a no no?!!). I did clean the pan in both transmissions ands instalkled new filters prior to the seap. I’m hooking up my Autel Scanner this am and while running taking off the cooler line to see if fluid is circulating. At this point im leaning towards the torque converter being toast as ive red thats a real posibilty. There seams to be an arugument between some if this will cause a basic loss of hydraulic pressure… You thoughts…?? i think its worth a shot to pull the used tranny out check the oil puimp and install a new converter before spending $2-6000 to rebuild. Ive got a guy supposedly eho can rebuild top to botom withe new electroincs for $2000 turn key witha waranty. I dont trust most transmission folk from past experiences… Your thoughts? TIA
TEX… quick update… I removed the top trans cooler line this am and ran the car… Tons and tons of flow from the cooler so we know the pump is working and the converter is installed correctly. i also connected up two way Autel scanner and in the limted OBDII of the 1995 there were no codes and the TCU was functioning normally… So… What next… ami correct in assuming the torque converter could still be bad or maybe a internal solenoid valve body issues on this 4 speed ??> TIA
ran the car with a cooler line disconnected and its moving a huge amount of trans oil so im assuming the pump is working fine and the TC id installed correctly
Disconnect the tranny from TCM - have you got warning light on your dash? Do you have it while switching it back again? If not. Your TCM or wiring loom is messed up. As i dicated earlier, I would opt for no power on TCM. Check the loom-to-tranny connector with multimeter. 4HP24 has solenoids that require power. Second thing - selector and rotary switch. What vin number you have? Was the rotary switch with new tranny or you’ve swapped these?