Hello to all fellow jag enthusiasts!

While I'm new to this forum, I'm very familiar with jags (especially XJ40). however, I have ran into a bit of a puzzle here... You see I have a 1991 Jaguar XJ40 4.0 Sovereign with all the goodies. I have managed to handle most of the maintenance by my self.. signals excluded of course

The problem is that NONE of my right signals wont work, all other lamps work as they should. I've checked the bulbs, all the control units, even tested the units with a meter and found no problems. I see the signal arrow in my dashboard correctly indicating that the signals should be flashing to the right, this is not the case however, nothing wrong with the sound indication either, basically all seems 100% normal from the driver's seat.

What makes this even more annoying is that sometimes, even if I did nothing to the car, the signals suddenly work normal, this might last few hours, days or even weeks. But just as it fixed it self it also stops working just as mysteriously.

My own conclusion of this fault is some kind of grounding error, because when the signals occasionally work, the flashing speed of the right hand signals are like double the speed to normal.

I'd really appreciate if someone could tell me of similar problems/solutions. I'm getting really frustrated because the hayne's manual is of little help, since there are a gazillion grounding spots in the car that are someway connected to the lamp system.

I'm getting a bit desperate here since that's like the only thing in the car that stops it from being 100% done with all systems working as they were when the car was built.

All help is extremely welcome!!! Thanks in advance!

Oh, btw.. once when I was doing some work in the engine bay I think I touched some of the wiring going in the right side of the car in the engine compartment, I'm not sure what I did, but after that incident the signals once again worked for like 3 days without any problems, but then suddenly they stopped working again when I was fixing the front passengers A/C beneath the passengers side dashboard.

 

Hi,

Can you clarify something? Are you saying that both the front and rear signal lights on the same side are not working at the same time? Or is it just one of them?

Also, what is the last six digits of your VIN? It will help in identifying the part number you have in the vehicle. Sounds like a problem with the BFM (Bulb Failure Module), but it would be odd that both are acting up at the same time.

The BFM's can develop minor cracks in the solder points, not sure if this is your issue or not. The VIN will help to some degree.

Let us know so we can help...

Rob Evenson

 

Yes, that's correct...

Right front, side and back signal wont work at all, and while they occasionally do, they do work simultaneusly.. so its like on/off on the right side signals

I once also tested the modules from the right side, and they seemed to be ok, some of the solder points were showing a bit of wearing, but checked ok on meter, so did nothing to them..

Also, I was wondering should I switch the modules from left/right, just to check if it's the modules...

My last 6 digits of VIN are: 631982

Thanks for reply

 

When you checked them,did you use a volt meter,or a continuity light. If a volt meter you may have enough voltage to move the meter,but not enough amperage to light the lights.Sometimes there is oxidation or corosion at the connections which will get good contact when jolted or when wet,best to clean them and use dilecteic grease on them.

 

Hi,

I was out of town for a few days and catching up on things.....

I agree with Lumppy47 on being thorough with the modules. According to the JDHT site (Genuine Jaguar Parts and Jaguar Accessories for Classic Jaguars) your VIN appears to have used the same generation module part as mine (583143), thus the modules are suspect. Odd though both at the same time. I wouldn't be 100% convinced they are sole source, that said, yes, switch them and see if the problem follows the modules.

Later today I'll check the service manuals and look for commons between the front and rear modules.

 

Hey!

Thanks for your replies, much appreciated. I'll try to switch the modules and see if I can get anything done, I'll post here when I get some progress (Hopefully) But for now, I have some other things to do, so it'll be until weekend I think.

And also, I'm gonna check the joints in the modules and see if there's some oxidation or something, Because I did actually check them last only with a meter that beeped when voltage went trough there. So I'm not really sure about the actual voltages, gotta check them out.

Thanks for your help!