Hi

I have a 99 XJR.

My issue is rear bulb failure message and no rear lamps.
I do have marker, license, brake, and fog lights working.

However, I CAN get the rear lights to activate under a certain condition.

After driving the car and turning it off, the rear lights WILL turn on if I turn the key to the on (not start) position. Its really weird and Im not sure what to make of it.

Ive jiggled wires and checked fuses....

 

First thing, Check the wires where they pass along the RH hinge. Pop the plastic trim off,
and cut the harness, open, look for broken wires. It's best to eliminate the obvious and simple things before pursuing the strange................

BTW, what lamps are you talking about? Just the taillights?

Failing any wiring issues, try doing a "hard reset" basically taking the positive lead off the battery terminal, and holding it to the negative terminal for 20 seconds or so. This resets all sorts of electrical gremlins. The tail lights are powered by the BPM, body processor module, so that may help.

 

Yes, I am just talking about the tail lights.

Ive discovered that they will turn on if I manually switch on the lights! Freaking weird. They wont come on if the light setting is on Auto.

I will double check the hinge area, I did not know about a plastic clip? Maybe I did, but either way Ill give it another look.

I did a hard reset this morning, want any help unfortunately.

 

Have you actually checked the fuses, or just looked at them?
If they run when you turn the headliguts on, and I'm assuming pressing the brake pedal as well, then it sounds like something could be getting crossed up between the brake light and parking light circuits. Usually symptoms like that would be caused by a broken fuse.

Unless of course, you've been playing with the wiring somewhere?

 

Dumb question-are the front lights working?

 

Yes, front lights work.
I have taken the fuses out to check them, but did not find anything.

To go back on what i said earlier, the tail lights DO NOT come on by using manual light switch instead of auto.

It seems, if anything, that they start to work after the car has been running for a bit. Its hard to identify a pattern.

 

What do you mean by 'check the fuses' though? A visual inspection can sometimes miss a broken fuse, you really need to check with either a multimeter/test light, or by replacing them with new fuses.

There is also a helpful electrical troubleshooting guide somewhere on this forum... I can't remember exactly where though, sorry. The stickys at the top off the page would be a good place to start though

 

I am not trying to "preach", but rather just remind you that accurate information is important in order to 1) keep folks trying to help "on track" with correct step by step troubleshooting plans and 2) prevent loss of interest in those trying to help.

You have already reported (in post 1) that the lights regularly work (in auto) after the car is stopped and turned to on, then (post 3) that they work in manual, then (post 6) that they work after the car is run a bit!

Again, not preaching, just asking you to run enough experiments that you can give accurate information. Do you own a 12 volt test lamp or a test meter? Can you follow a schematic? Do you intend to work on this yourself?

If you have the tools and want to tackle it, i am pretty sure we can help you correctly diagnose it pretty quickly. Or, it might just start working right again by itself!

 

JagRepair.com - Jaguar Repair Information Resource has the entire 158 page wiring diagram for free.
1.Download it.
2. Print the pages you need.
3. Get out a Volt Ohm Meter.


Now you are loaded with ammunition and ready for battle.
1. Start with the easy to access areas. Open the trunk and remove the connector to the tail light. Does the bulb get power? Does it have a good ground? If the
easy doesn't work, then go for what you think is most likely.


2. If it works in manual, but not automatic is the switch bad or the wiring to it broken? Since it is on the column and not the steering wheel, the clock spring is
not an issue. Accessing this are involves standing on your head and removing
screw under the column plastic shroud. This can take a few hours the first
time you do it.






3. A hard fail is "easy" to find. If it is intermittent, it takes patience.




Just to keep you on the right path........
The tail light wiring doesn't go through the right side hinge. That wiring powers
the power lock, License plate lamp and the trunk lid lights. If I understand correctly
those are all good.


Good luck.

 

Thanks guys, Ill get serious and buy a test light!
Will report back...

 

I like a test ligth over a meter because 1) you can see it easier while standing on your head, and 2) it provides load to the circuit so stray voltages do not lead you, well, astray! It is nice to also have a meter, especially for measuring resistance when the circuit is off, but the $3.00 to $7.00 meter from Harbor Freight works OK.