Hello,
I'm in need some some help. Just picked up a 1991 jag xj6 sovereign. One of the issues when I first got it is the low beams aren't working I checked the fuse and the fuse is blown and got one lamp of the low beam to work and the other one wouldn't work the one that didn't work was on the driver side then I replaced both bulbs for the low beams and the driver side low beam still wouldn't work not sure where to go now is it a relay could it be the lamp module control.
Thank you,
C

 

Welcome to the forums Chandler scully,

I've moved your question from General Tech Help to XJ40 forum. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Hi Chandler,

Welcome to the Jaguar Forums! It's great to have you with us!

A common problem with XJ40 headlamps is the Bulb Failure Module (BFM). You will have to do some electrical diagnosis to determine whether your issue is in the BFM or elsewhere. A basic digital voltmeter/ohmmeter (DVOM) is the best tool, but if you're careful a 12 volt test lamp can work.

You can easily test for approximately 12 volts across the terminals at the headlamp bulb socket. If no voltage is present with the engine running and headlamp switch in the ON position, shut off the engine, disconnect the BFM connector and connect one of your DVOM test leads to the Brown wire with Orange tracer stripe and the other to a good ground, such as the ground post on the left inner wheel well. You should have battery voltage on that wire from Fuse B8 (15A) in the left A-pillar fuse box.

Next, measure for battery voltage on the Brown wire with Black tracer stripe. This wire should always be hot from Fuse C6 (5A) in the left A-pillar fuse box.

Now turn the ignition to position II (ON) and test for battery voltage on the White wire with Green tracer stripe, which receives ignition-switched power from Fuse 1 (3A) in the Center fuse box.

If you don't have power on one or more wires, check the fuses.

If you have power on all three wires, suspect your BFM. Sometimes they can be resuscitated by re-flowing the solder on all the joints on the circuit board.

One other suspect is the Switch Pack/Lighting Logic Module on the steering column.

You can download the wiring schematics for your car at this link:

Jaguar XJ40 Electrical Guide 1991

Another helpful document is the Haynes manual. You can download a mostly-complete U.K. edition here:

Haynes Jaguar XJ40 Repair Manual

Cheers,

Don

 

!00% what Don said and I'll second the reflowing of the solder joints. These older cars had huge circuit board and with an inexpensive solder gun you can fix almost anything electrical. Some of the relays and the "modules" in the lighting have ridiculous core charges or a replacement part and thats a guarantee they can be re-soldered.