Hey all,
I have a 98 XJR. Runs great, but has a 'Rear Bulb Failure' warning light. Brakes, turn signals, side running lights, fog lights all work. Just no running lights. Also to verify, there are only 4 bulbs per side in the rear light assembly right?

The bulbs when replaced still do not work, and there is 0.11 volts approx across the bulb (with the bulb in or out) when there should be voltage.

Someone told me that there was some module that needed to be replaced. But is there anything I can do before buying one to test and see what it could be?

I already pulled all the fuses purported to be related. I have read pages of comments on there being poor contact and I *don't* think that's the issues.

Any help will be appreciated, I'll even offer a few $ kick back via paypal or bitcoin if someone can help me figure it out!
Thanks a bunch!
ejb, new owner of a gorgeous Jaguar.

 

Yes, only 4 bulbs per light unit.


The rear running lights are 5w/21w twin filament bulbs , not single 21w bulbs , as it is the same bulb as the brake lights.


Have you got running lights at the front ?
If not it could be the light switch.

 

Ah, so when looking at the left light fixture from behind the car, what is the upper right light's duty?

And would the switch trigger the rear bulb failure error?

I'll check the front later today.

 

From the rear, the upper right bulb is the reversing light. On the left side rear light unit.
The brake light/ running light is lower left on the same light.

 

Looks like no running lights in the front either.

 

You should really give the fuses (all of them!) a once over. Then you (or somebody) needs to get a schematic and trace the problem. It should be fairly starightforward and quick to figure out.
I strongly recommend against trying to replace modules to fix this one until you know that is where the problem lies, because there is NOT a common module failure to cause no running lights. More than likely, you have a fuse , switch, or connector problem.
Please report back what you find.

 

Do I understand this correctly? Neither your headlights nor rear running lights are working? Sounds like a broken wire in the multifunction switch. The switch on the left side of the steering wheel. Does not sound like bulbs or fuses.

 

Front headlights work, side front orange lights work, Front facing orange lights do not.

Side rear orange lights also work. I'm not sure which front lights are supposed to be on at different contexts, i Just bought the car

 

Do you have an owners manual? If not, down load it from the stickies, it will tell you what lights are on at various switch posits. Are your brake lights -- see previous -- single or double filament bulbs? If double, check wiring in loom on right hinge. If single, install the correct bulbs and report.

 

I checked all 15 amp fuses with a multimeter, will check more. Got the BPM out.
Should I be poking the multimeter leads into the wires or should I be testing only at exposed end points?

Thanks all for the help.

 

Look at this thread (go to its post# 3 list of issues - rear lights & slcm info):

https://www.jaguarforums.com/forum/x...estion-120843/

also posts 2 and 4 in the following thread:

https://www.jaguarforums.com/forum/x...issues-126542/

Jim Lombardi

 

I used my 30 minutes of free time tonight to check every fuse.

Also, I checked the voltage to the double filament bulb. Right one was at 12.5 volts, looked good (but must be a weak current carrying ability if that couldn't light up the double filament bulb that it was attached to. BTW all filaments tested at 3.5 ohms.

And then the left side double filament voltage test was at 8.5 volts. Huh. THEN of course, due to those spring leads that the bulb connects to are close together...and i must have arced them. Because now I got rid of that 8.5 volts! Bleh. 0 volts now.

I have done a good amount of electronics testing but never much with tracing circuits. It's gonna take a long time to dig into it.

The wires in the right hinge all look good. Also., the previous owner left an obvious trail of testing the same things.

 

Jim, I did read those. Haven't found any bad fuses though and I've tested all of the ones on the inside and in the trunk.

Lastly, I found one bad bulb in front, can't seem to get the front facing orange lights disconnected (the ones in the bumper), and found that the orange/black, yellow/white, and of coure the black ground wire on the left side rear lighting assembly are grounded out. Seems like that would be wrong. Also, those position wires on the right assembly are not grounded out.

I downloaded that wiring PDF that you uploaded and will study it later today. The only reason why I don't want to take it in to get this work done is because I want to save that $ for mechanical work, but it's probably already time inefficient for me to be doing that....what can I say I like to become frustrated by working on cars...it's worth it if I can ever get it fixed!

 

Here is the instructions from the 1999 Jaguar XJ Vehicle Care Handbook on front (bumper) side marker light removal:



Notice the diagram (arrow) shows the downward direction (counter-clock wise) to remove the bulb holder.

Also the front directional (in bumper) indictor light:



Notice its diagram (arrows) shows counter clockwise twist to remove the bulb holder.

Jim Lombardi

 

Ok well now the trunk is not able to be opened with a key, with the inside button, or the outside button. After it didn't work, I googled and tried toggling the locks, then the valet switch. I can't hear a sound when I press the open button.

Any way to fix that myself or do I need to take this thing in now?

 

Look at the " master key locked in trunk - how can i open trunk now" thread:

https://www.jaguarforums.com/forum/x...esolved-58948/

Jim Lombardi

 

Got the trunk back open and now it works again...strange. Anyway, onwards!...tomorrow!

 

Check the wires that run along the trunk hinge, it is very common for them to break and cause all sorts of intermittent problems.

 

I did check the wires visually, but how else do I check them since I saw nothing visually broken/bent?

And now to finally confirm: the only lights that are not working are the rear running lights. I'll replace both brake bulbs tomorrow, but I don't think that's it seeing as how it looked like I didn't have voltage across the left bulb.

 

Here are some of the posts on the wiring in the boot rear right hinge area:

SeanB: similar problem, I went back to the wiring loom, and cut through the material tape carefully right back to where it meets the boot loom, needless to say an earth cable had neatly split. I soldered it back together, and shrink wrapped it, all good since.

steve11: Almost always a broken wire at the harness as it bends by the trunk hinge. The wire will break inside the plastic insulator and often will show no visible signs of failure.

Test each wire by hand by flexing at the bend. You'll feel slight resistance until you reach the broken one. It will not have the same resistance.

JimmyL: Open the trunk and pull the plastic cover off the right boot (trunk) hinge. There is a bundle of wires that pass through there. They frequently break, as in, they all do it eventually. Unwrap the wires and fix any existing broken wires securely. This is posted on every Jaguar forum in the universe.

Elvin
When you mention the running lights not working, do you mean the tail light blub not lighting when you turn on the headlights?

Look at the Stop/Tail Light Bulb (B) in the diagram below - it has 2 filaments in it - one is for the brake (stop light) and the other is lite when the head lights are on.




Stop/tail light bulb - Capacity is 12V 21/5W; Type - Twin filament bayonet long life

Jim Lombardi