Hi All

I have a problem with the headlights on my 1991 4.0l facelift coupe.

The problem is that the dipped beam (low beams) go on ok albeit that they are not very bright and the full beam (high beam) do not go on at all.

The high beam flash will work when the stalk is pulled back, just will not stay on.

I have tried four different stalks and the problem remains with all of them so I have dismissed the switch/stalk as the problem. I have also fitted a substitute headlight module and again it makes no difference.

when checking the voltages at the headlight module I noticed the voltage at the low beam to fusebox/bulb output pin was only 6v. Looking at the wiring diagram this looks like a direct battery feed so I would have thought it should be 12v.

Anybody know what is wrong as I cant work it out.

thanks in advance

Chris

 

It sounds like you have a bad earth, hence the low Voltage reading.

 

Hi

I was pondering the earth, would this be the earth in the switch, module or bulbs? or all three.

Ive just resprayed the car so could have disturbed something during strip down and rebuilding.

just thought that as the main beam works during flash that the circuit must be working

Chris

 

Hi All

You may remember I have been struggling the last week with dull headlights and no main beam except on the flash. I checked the earth points on the radiator support, changed the headlight module and tried four separate switch/stalks and none made any difference. I also noted that the dipped beam output pin on the headlight module was only showing 6v, and being a direct feed should have been 12v.

After studying the wiring diagram emailed by Jonnie I noted that the headlight relay was a common relay, supplying power to the headlight module and the fog light switch, This seemed the only common area of both faults so today I concentrated there.

The relay was working so I examined the relay plug and its wiring. here I saw that on one of the terminals that instead of having a coloured wire had only bare wire coming from it, and was snapped. I unbolted the relay support bracket and fuse box to get a better look at the wires and saw another bare wire coming out of the wiring loom. unwrapping a bit of the insuation tape on the loom showed that this was the thin brown wire that goes to terminal 30 of the headlight relay. the direct battery switched feed. Joining these wires together and 12v showed on the low beam output pin of the headlight module, and the main beams now worked, so this broken wire has been the cause of the faults.

i started to unwrap the insulation tape around the wiring loom looking to find the start of good wire and was shocked to see that the whole of that particular wire inside the loom has melted, some stuck to other wires and some areas just bare wire. I have unwrapped as far as where the loom goes into the inner wing near the bulkhead and all of it is damaged. I now need to remove the wheel and the rear splash guard to continue tracing the wire back and find the good section of the wire so I can replace the damaged section. I'm not sure where this wire finishes or goes to a connector, and am suprised with the damage, both what caused it and the fire risk it could have been.

Chris