Just added this 1988 XJS-C to my collection and I have no headlights or parking lights . If I use the column stalk I have turn signals and can flash my high beams so at least I know my headlight bulbs are fine. I also have both brake lights and the third brake light. Don't know where to start with this problem. Could it be the Headlight Relay located in the engine bay. I can hear it click when I engage my highbeam lever. Why don't I have any headlights or parking lights? Am I missing something?

 

Having recently experienced something very similar, I'd suggest the easiest thing to check is that relay at the front. Swap it for one of the other identical ones there, and see what happens... or does not happen, as the case may be.
Also, I believe high beams use separate bulbsfilaments to low beams.

 

So, you have no low-beam headlights.

It's possible that both low-beam elements have burned out. The outboard headlights ("low beams") have two filaments, high and low. If the low elements have burned out the high elements would still come on when you flick the stalk switch.

Have you checked the headlight fuses? Each low beam filament has its on fuse. Even if not blown the fuses could be dirty/corroded...as could the sockets at the headlights themselves.

Voltage for the low beams does go thru the headlight relay so a faulty relay is certainly possible, but I'd check fuses and connections first, personally

The front parking lamps have left and right fuses as well, but they're paired with the side marker lamps....so if the side markers are working, the fuses are OK

Cheers
DD

 

I get absolutely nothing when I turn on the headlight switch,no headlights,high or low beam,no side lights or parking lights. I've checked the two fuses located under the passengers side dash and the fuses are fine but it seems there's no voltage or very little getting to them. Does this lead back to the headlight relay located on the drivers inside fenderwell located just behind the headlight? Could that be the culprit. Is there any way to test this relay?

 

Sure. Do you have a meter or 12v test light?

Brown wire at relay -12v at all times
Blue wire- 12v when headlight switch is turned on
Blue/red wire - 12v when headlight switch is turned on
Blue/white wires- 12v when high beam selected or headlight flash selected
Blue/black wire- ground when stalk switch is operated

At the headlight switch itself you can make some checks:

Brown wire- 12v at all times
Blue wire - 12v when headlights turned on (same as blue wire mentioned above)
Red/slate wires- 12v when park lights or headlights turned on (this is the feed for marker, park, license, and tail lights)

Post back with results !

Cheers
DD

 

Something to consider:

Since the so much of the lighting system is inoperative it is reasonable to suspect a problem well upstream; the headlight switch specifically. This would be particularly apropos if all the lights stopped working at the same time.

However, since the car is new to you, you don't know if that's the case. The various lights might well have been failing one-by-one over the years.

It is possible that you have a stack-up of several faults, each of which must be sussed out.

Cheers
DD

 

If it's the headlights,,, all the parking lights and the license plate lights???? BUT lights (some) basically work with the stalk, I would suggest the dial style switch used to turn parking and headlights on, in general. The main light control switch might not be wired, fried or shot all together. There are lots of used options on fleabay...

 

Problem Solved : As it turns out,the main Brown wire supplying power to the headlight switch was disconnected off the back of the switch,not distributing power anywhere. I simply reconnected it and now have power to the headlights and parking lights. I'll wait until later on whether I have interior dash lights as it's too bright out to see them. Thanks to All that have helped!