1991 Explorer Eddie Bauer LH headlight dim, goes off when high beam switched on

[Snorri]

I have been trying to search for a solution to this problem for weeks now. The left hand (drivers side) headlight is dim and goes off when I flick on the high beam, with the multi switch in the stearing column. It also goes off when I unplug the right hand bulb from the connector. I have cleaned all (I think) grounding connections for the headlights, all fuses are ok, all bulbs are ok.
The car seems to have some sort of daylight running light mechanism as the lights come on without pulling the headlight switch (can´t find this mechanism though).
Can anyone help me please with this extremely annoying problem that refuses to go away?

 

[rookieshooter]

This is a wiring for a 91 Ex. Notice on the Dimmer/Flash to pass switch that there are two seperate switches, one for the left and one for the right. Might just be this switch. If there was only one switch it would seem to me that then both would go off. If you do find out....Please post

 

[Snorri]

Still searching....

Rookieshooter

Thank you for your reply.
Dismantled half of the dashboard yesterday evening, after having found out that the original daylight running system is NOT installed in the car (should be behind the LH headlight inside the engine compartment [a black box with went fins on it]). I found an aftermarket daylight running system installed, by a previous owner, in the car, unplugged that and no change in the headlight problem. (There were stupid laws in effect in Iceland, some years back, that forced every car owner to have this system installed!!!!!)
Leaning towards the multiswitch now and will endeavour to find one today (not available at the dealership - last price was USD 200).
Will remove this aftermarket daylight running system and install the OEM equipment that I can get for a good price at the Ford dealer here in Iceland.
Will post again when problem is fixed.
Anyone else out there that can contribute?

 

[MAXIMIS1]

try to manually ground the failing light/fixture . then unplug the working bulb, as you said above it makes the light go off "usually". if it still goes off "idono" . if stays on repair some or one grounds . ... really a need see nightmare so good luck.

 

[bzmek]

Re:91 EB headlamp dim

Had same problem on my daughters 97 eb. It turned out to be the "DRL" module that was located in the console to the right of the shifter. Think it cost us about a $100.00 from dealership. I also chased the I've got no "DRL" system scenario, only to find that the module exist anyway. Hope this helps.

 

[Longjohn119]

Do all the '91 EBs have DRL or is mine just not working (no other problems with lights)

 

[rookieshooter]

Do all the '91 EBs have DRL or is mine just not working (no other problems with lights)

Just noticed that the diagram I posted does in fact show a DRL and you can see the wires going to it. That pic is of a 92 Ex, it does not show where its located at but you might be able to follow the wires.

 

[DeRocha]

This may seam like a stupid question, but have you verified the bulbs work? The bulbs use a 2 filament system and it is possible to have either the high or low beam blow out without affecting the other. Since the wiring harness plastic connectors can get brittle with age I would I would replace the affected bulb with a new unit rather than trying to swap sides to see if it works.

 

[Snorri]

Do all the '91 EBs have DRL or is mine just not working (no other problems with lights)

NO all 91´s do not have the DRL installed. The location is just above the LH headlight and it is a small black box with went fins (similar to those on a computer CPU). If it is not installed you will see a wire connector, with a plug, attached under the hood immediately above the LH headlight.

 

[Snorri]

This may seam like a stupid question, but have you verified the bulbs work? The bulbs use a 2 filament system and it is possible to have either the high or low beam blow out without affecting the other. Since the wiring harness plastic connectors can get brittle with age I would I would replace the affected bulb with a new unit rather than trying to swap sides to see if it works.

No question is a stupid one. Bulbs and connectors are fine. The only problem is that the LH headlight is dim and goes off completely when I switch on the high beams. RH headlight is fine.
Found out that there is an aftermarket DRL installed, underneath the dashboard, unplugged that and no change.
Have cleaned all under hood ground connections and no change.
Found out that there are three ground connections on RH side under neath the dashboard to the left where a front seat passenger have his/her feet. Will have a look at those tonight.
Have unplugged the multi switch on the steering column (high beams, turn lights and hazard switch and no change.
Next in line is to manually ground the headlight (should have done that a long time ago, STUPID ME - thank you MAXIMIS1)

 

[Snorri]

You Will Not Believe This!!!!!

This may seam like a stupid question, but have you verified the bulbs work? The bulbs use a 2 filament system and it is possible to have either the high or low beam blow out without affecting the other. Since the wiring harness plastic connectors can get brittle with age I would I would replace the affected bulb with a new unit rather than trying to swap sides to see if it works.

I have finally managed to fix this problem. Did, manually, ground the headlight last night - NO CHANGE.
Had bought the headlamp (the mirror was bad and leaking), installed that - with the new lightbulb - last night and guess what??? Everything worked fine!!
I had been told, by a mechanic that looked at the car, that this was definitely a grounding problem and when I looked at the bulb, both filaments in the bulb were intact and fine. When I switched the bad bulb last night, with the ok one in the RH head light, the same problem occurred there.
The problem? - DEFECTIVE BULB!!!

AGAIN MANY THANKS TO ALL.