Hello. I'm chasing a weird fault, and I do not have a wiring diagram. The two buttons that release the boot latch and the gas door latch are not working. I did find a broken wiring harness (3 wires) inside the wiring loom in the boot lid. That was repaired. Any thoughts where I should start? Cheers, Steve.

 

Fuse?

 

That was my first thought. I can't find anything related to what I'm looking for. There are 5 or 6 fuse blocks in the car.

 

That was my first thought. I can't find anything related to what I'm looking for. There are 5 or 6 fuse blocks in the car.

 

Hi Steve,

You can download the wiring schematics at the link below:

Jaguar X100 Electrical Guide 1997

When I encounter two nearby circuits that are not functioning properly, the first thing I look for is a bad shared ground. I would start by inspecting the grounds near the battery for corrosion, looseness or broken wires. Often corrosion is not visible until you remove the nut or bolt and inspect the eyelet/ring terminals on the ground wires. Clean the terminals, star and flat washers, threaded stud or bolt, and nut and reassemble. Do not overtighten - just snug it well. If you don't find any issues with the grounds near the battery, check the Electrical Guide for other possible ground locations and for the wiring to the SLCM and fuses.

Cheers,

Don

 

Are the remote fobs & locking systems working OK?

 

How do you know it was repaired correctly?

 

The first thing to check are the fuses..

 

The boot latch solenoid and fuel fill flap solenoid both receive power from the Security and Locking Control Module (SLCM), so if the key fob remote works to lock and unlock the doors, the fuse is OK.

Cheers,

Don

 

Sorry, I didn't know that. I assumed there was a dedicated fuse, since there are hundreds of them! So the problem is definitely in the wiring or the security module.

 

Thanks Don B. Now that I think about it, the key FOB hasn't worked for several years, however, I never noticed the trunk/gas door issue. Very interesting.

 

Further to Don B's good advice, the gas flap and trunk latch do share a ground connection. It's on the righthand side of the trunk, next to the main battery ground point.
That seems to me to be the simplest point of commonality to check first.

 

Hi Steve,

Well, when our only clues were the inoperative trunk and fuel fill flap buttons, the shared ground was the most likely suspect. But now that you have added the inoperative key fob remote to the list, the next question is, "What else is not working?"

Trying to help you diagnose without a complete list of symptoms is a guessing game, and we don't like to guess if we can avoid it.

Cheers,

Don

 

Of course, guessing is always incorrect, for me anyway. I never drive this car as it's my wife's. I know that key FOB issue was acting up way before the other boot/gas cap issue. She just manually locked and unlocked the doors. I will investigate the ground points. As an audio technician, retired, I used to chase down all kinds of weird faults. This is going to be fun actually. Cheers, Steve

 

Don, to your point, I'm now chasing down my main issue on this same car. Intermittent no start. The gas cap and boot issue can wait. Very intermittently, the starter will not make a sound, no attempt at engagement. The other day, when the car started, I had 12v on the solenoid terminal on the starter itself. The car started just fine. Today, 0 volts and obviously no start. I did hear what sounds like a relay click under the hood on passenger side. This has been acting up for 2 years now which is why it's been garaged. Thanks for your guidance. Steve

 

Hi Steve,

Lots of possible causes but the first thing I'd check would be the starter relay, which is in the right side "brake booster" compartment at the firewall where the ECM will be if your car is LHD. Inside that compartment, there are three relays along the right fender. The forwardmost relay is usually the starter relay. If you still have the original brown relay there, try swapping in one of the nearby brown relays and see if the behavior improves. If you have the tools to test the relay, that's a good idea. The original brown and blue relays do fail intermittently with age.

Other suspects include the ignition switch, Body Processor Module, corrosion in the High Power Protection Module, contaminated connections at the starter or engine ground strap, etc. If you don't have the wiring schematics I can post them.

Cheers,

Don