New thread, rather than continue under the mis-leading title here: https://www.jaguarforums.com/forum/x...ectors-259720/

Problem has been isolated to the "Accelerator Pedal Circuit C"
- Car cranks but won't start (no fuel delivery signal)
- Error thrown at ignition on (problem exists before trying to start the car) - presumably seen as serious enough that it doesn't allow any fuel to be delivered
- "P0226 - Pedal position sensor C circuit range problem"

Pedal consists of 3 potentiometers working independant of each other (with broadly similar resistance ranges).
- Circuits A and B have fairly similar output voltage ranges on the OBD2 scanner
- Circuit C has a significantly lower output range (with a very messy plot)
- Circuit C has a totally "clean" plot with a normal range when Circuit C on the pedal is connected to Circuits A or B on the wiring loom

Conclusion: Pedal is good. Wiring / ECU for circuit C is not.

Question:
- Do ECU's go "bad" in this way?
- Could it be a bad / corroded ECU connector? (Connector next to the fuse box under bonnet is all good)
- Are the ECU connector 5 point security screw bits commonly available?
- If it's a bad wire in the loom... any suggestions to trace it? Or just re-route a new wire somewhere convenient to get the car running?

Any other thoughts welcome!

 

It does sound like a, corroded connection, or partly broken/corroded wire.

I had a boot latch problem a few months ago, where the motor wasn't strong enough to open the latch, and I was convinced that it was a bad motor, because the voltage was fine on the multimeter, and so I bought a new actuator, but it was the same. I found out then that it was a partly broken wire.
It was acting like a bad motor, working bad the first time, then weaker the second time, and not working at all after that, until I came back later and it would partly work again once or twice.

And yea, you can get those security bits easily. I picked up a set a few months ago for really cheap for €7. See here:

 

So... pulled off the ECU connector and did a full test on all the wires. Everything was 100% healthy and normal. Finally tested the voltage output on the three circuits, 2 out of 3 giving a perfectly clean 5v, the 3rd is giving a very messy 2v.

Given that the wires were all 100%, and I can't test the output right at the ECU I don't think, I can only assume that there is a bad joint or component INSIDE the ECU.

I then tried "sharing" the 5V feed from one of the other 2 circuits with the input to circuit 3 and *tada* the fault disappeared and the engine started.

QUESTIONS:
1. What lives inside the ECU? Is there any likelihood that I might find something repairable?
2. "Sharing" the 5V feed reduces redundancy in the system, any other major downsides?
3. Any other alternatives I should consider?

 

Do you have the X-Type Electrical Guide?

Here's a link to it in case you don't: https://drive.google.com/file/d/1Jmm...ew?usp=sharing

I assume you have the workshop manual, yea?

 

Thanks @gijoe50000 , yes - the electrical guide was invaluable.

Currently the car is up and running with some pins and a crocodile clip in the back of the pedal connector to share a good 5V feed to pedal circuit C. Just need some connectors to make it a bit less Heath Robinson-esque!

Scanner was essential to pin-point the exact circuit that was failing. Money well spent imo! And now I have the JLR scanner, I can justify to the wife that it just makes sense to buy an old Range Rover