No start after adjusting gear shift cable

The Daimler V8 auto gear display in the binnacle was not lined up with the pointer which really annoyed me so I managed to adjust it by tightening up a loose nut on the linkages and getting better clearance between the dash and the top of the steering wheel cowling. I didn’t actually adjust the cable length as I could not reach to unclip the ball joints so it was just a bit of fettling.
I now have no start on the button. I can start with ignition on via the relay button so I know the system is still alive. I have 12v in and out the start button.
Looking at the wiring diagram it seems the circuit is controlled via the inhibitor switch on the gearbox so I must have moved the gear linkage enough to trigger the inhibitor switch. Do I go underneath and try to adjust the cable there or should I do this from up above behind the dash?

Hello,

The inhibitor switch for MK2’s equipped with the Borg Warner DG250 Automatic Transmission is affixed to the steering column behind the dash (The red arrow is pointing to it). there is an alignment procedure in the factory service manual that describes how to properly align the switch housing relative to the lever arm.

When the gear selector is placed in Park, and the inhibitor switch arm is properly aligned with the switch housing, the circuit will be completed and allow the starter to crank when the starter button is depressed. If the arm is not aligned properly relative to the switch body, the circuit will not be completed and the starter button will not work.

I suspect your switch became misaligned when you realigned the pointer. The photo that I attached shows that there is a relationship between the pointer, gear lever and inhibitor switch. Readjusting the inhibitor with per the manual should have you underway again. This will not affect your pointer location.

I had to go through the alignment process when I restored our car. I wish that I had known about this BEFORE I installed the column as it’s a lot easier to adjust on a bench versus standing on one’s head under the dash.

I hope this makes sense and helps.

Brian

Mine is a BW35 so no electrics on the column. The switch is on the gearbox and hard to get to.

Hi Brian,
This is very helpful. Thank you. It seems as though I am somehow getting this backwards.
When sitting in the drivers seat, gear lever in park (up or as far anti-clockwise as it will go), the switch should connect pins 2 and 4. Which is power and starter solenoid.
This would be with the switch arm full clockwise, right? This is the part I dont get. Seems to be fully acw instead.
Also the switch seems to connect pins 1 and 3 when in the reverse position. I would have expected 1 and 4.
I can always start the car at the solenoid on the engine bay firewall, but button is inoperable.
Also the adjustment in the manual you mentioned - can’t seem to find it. Page #?
Cheers
Dave

Hello Dave,

To confirm the adjustment of the switch, place the gear selector in Park and verify that the small hole located on the arm of the switch is aligned with the corresponding small hole on the switch housing. If you can insert a small wire (i.e. a paperclip) through both of these holes while the car is in Park, the switch is adjusted properly. If not, slightly loosen the clamping bolt and rotate the switch housing such that the holes align when in Park and then tighten the clamping bolt.

I seem to recall that the wiring schematic in the Jaguar service manual is incorrect for this switch. A continuity test with an Ohm Meter will verify which numbered poles on the switch operate in the park position and enable the starter and run circuit and which numbered poles complete the reverse light circuit. Once verified, compare this with the wiring diagram and see if it makes sense. The wiring diagram indicates the following

Pole 1 - White/Blue to Starter Push Button
Pole 2 - White/Red to Starter Solenoid
Pole 3 - Green/Brown to Revers Light
Pole 4 - Green to A4 on the Fuse Block

I hope this helps.

Brian

Hi Brian,
Thanks for this. Having reread the manual, your description is correct except the alignment of the two small holes is when the gearbox is in drive, D, not park P. At that point it seems as though pins 1&3 are connected. Push button and reverse?! Makes no sense
If it is as you say in park, still makes no sense.
The only setting when these small holes align that makes any sense is if the gearbox is in reverse. And even then I would have expected pins 4&3 to be connected to light the reverse light.
Doing more investigation. Thank you for your help so far! Always interesting.

Hello David,

I stand corrected…The gear selector should be placed in Drive (NOT Park) to perform the adjustment. I apologize for the mistake!

If we disregard the wiring schematic for a moment, here’s what we know.

When in Drive and with your switch adjusted properly, Pins 1& 3 are connected.

When in Park, we want the White/Blue wire (to the Starter Button) and the White/Red wire (to the Starter Solenoid) to be connected via the switch.

When in Reverse, we want the Green/Brown wire (to the reverse lamp) and the Green wire (to the fuse block) to be connected via the switch.

Here’s what I suggest…

With the adjustment already confirmed, place the car in Park and determine which pins are connected. We will want the White/Blue and White/Red wires on these pins.

Next, Place the gear selector in Reverse and determine which pins are connected. We will want the Green/Brown and Green wires on these pins.

If we are looking at the pin side of the switch as installed on the column, they are facing forward toward the bulkhead/toe-boards (ref. the diagram). When facing the switch pins and the gear selector is in Park, the switch arm will be rotated fully clockwise relative to the switch body. Two pins should be connected in this position. ID which two pins they are and make a note. The Starter Button White/Blue wire and Starter Solenoid White/Red wire should go to these pins.

Next, place the gear selector in Reverse. the switch arm will be fully rotated counter-clockwise relative to the switch body. Confirm which pins are connected in this position and make a note. The Reverse Lamp Green/Brown wire and Power Green wire should go to these pins.

The exact wire to pin orientation will depend on the contact/disconnect sequence as the arm rotates across the contacts. We want the Starter Button (White/Blue) wire to be isolated as soon as the arm rotates counter-clockwise off the Park position. Likewise, we want the Reverse Lamp (Green/Brown) wire to be isolated as the arm rotates clockwise from the Reverse position. Knowing which pins are connected where in the gear selector range of motion will help determine which wire should be attached to a specific pin within the aforementioned pin pairs.

I struggled with this myself. I seem to recall that the wiring schematic in the Jaguar Service Manual is incorrect. By performing various continuity tests throughout the gear selector range of motion, I was able to determine which wire went to which pin. I regret that I did not make note of this in my wiring schematics. When you sort this out, it will be helpful to others (and me) if you post your final wire to pin configuration.

I hope this helps!

Brian

Hi Brian,
Eureka! Your first principles suggestion did it.
To confirm, I jumpered the W/U and W/R wires together and ignition and push button work.
I jumpered the G and G/N wires together and reverse light works.
Seems the pin numbering on the switch and diagrams is at fault.
This is what was getting me in circles.
The switch actually connects pins 1&3 in “park” and 2&4 in reverse.
The wiring diagrams have
Pin 1 W/U to push start
Pin 2 W/R to starter solenoid
Pin 3 G/N to reverse
Pin 4 G to power.
This is incorrect.

It should be
Pin 1 W/U to push start
Pin 2 G/N to reverse
Pin 3 W/R to starter solenoid
Pin 4 G to power

Phew, then all adjustment procedures work fine. Really grateful for your assistance and approach in this.
Cheers,
Dave

Yay…Great news!

I’ve updated my wiring schematic as well to capture the fault.

I’m glad that you could sort this out.

Happy motoring!

Brian