My 1995 XJS lights the 'Bulb Out' warning light whenever I turn on my lights (Parking or head lights). All bulbs do light up, I think, and the wiring diagram suggests that only the running (parking) lights, turn signal bulbs and brake lights are monitored.

I need your advice on what else to look for or do. Replace bulbs with new ones to compensate for increased resistance that comes with age? Clean all bulb sockets?

Thanks in advance for your help.

 

Near as I can tell there are 5 bulb failure units: one for brake lights, and then 4 units for parklamps, marker lamps, license lamps, etc.


Not sure about the brake light BFU but the others are a bi-metal switch type of thing. The switch is closed (warning light on) until the current flow heats the switch and opens the circuit.

The brake light BFU might be solid state. Not sure.

Anyhow, I'd unplug the white/slate wire from the four bi-metal BFUs one at a time and see what happens. If the dashboard warning light goes out then you've at least isolated the problem somewhat.



Good to clean sockets etc on general principles.

Cheers
DD

 

On my 1985 (and all pre-facelifts AFAIK) the bulb out warning light is meant to come on when the lights are turned on. It stays on for about 30 - 45 seconds and then goes out. This is intentional and part of the system design.

Does yours stay on for good? As it is a facelift, I do not know if the same start-up system has been kept.

Greg

 

My '93 facelift has the same system and the failure light stays on for about 30 seconds; have you checked the brake lights? Before messing about with the electronic side of things clean all the bulbs and holders as suggested.
Steve

 

my '92 does the same. Warning light comes on every time I turn on the parking or headlights and stays on for a 30-40 secs. Far as I can tell all my bulbs are working including brake lights.

 

Mine started doing the same thing day before yesterday. As far as I can tell no bulbs are out but every time I turn on the headlights that warning light stays on.

 

My warning light comes on as soon as I turn on the lights and stays on. I will begin disconnecting the 'bulb out' modules as suggested to see if I can isolate the problem and also clean all the sockets. I did not check the license plate bulbs, so possibly, if they are monitored, could be the problem. I will post with progress.
Thanks to all.

 

The BFUs are chassis-grounded. Unbolt them and clean up the mounts.