Weird electrical headlight issue....

[DeLorean937]

So i'm stumped. Ive never had an issue before today with the headlights.

Basically, the issue is that when I turn the headlights on, and I pull the switch all the way out the headlight stay on. No other lights are on, with the switch pulled all the way out.

I thought it might be the switch so I pulled it out and made sure the connection was connected properly and it was. I also checked the relay for the low beams and it looked fine.

This is the weird part, when I pull the fuse for the low beams (#14) everything functions as it should. Lights switch on and off perfectly. Should I leave the fuse out? Any help would be amazing.

-Robert

[Bitsyncmaster]

What do you mean "pull the switch all the way out"? Our headlight switch is a push button switch.

[DeLorean937]

All way out as in the "off" position. As in the switch is sticking all the way out and nothing should be illuminated.

-Robert

[Bitsyncmaster]

So you have the original (not the DMCH electronic) switch and when you have pressed it twice (switch is in off position) your headlights remain on but the parking and dash lights go out.

Sounds like a problem in the switch itself.

[DMC5180]

Do you have an Original switch? If so the internals may have gotten Hot from high load resistance and melted in such a way that does not allow the contacts to release. Although usually the switch will fail and not turn the lights on. You could also have a stuck main ON headlight relay. You easily swap out the relay with the high beam one to verify it. Stranger things have happened. Beyond that there is no other way to get power to the headlights. Except the Flash to PASS function of the the Column switch.

If you have an New style DMCH switch. It is possible for a Logic box relay to stick ON not allowing it to turn off. This actually happened to me ONE time. However the reason it happened to me was my fault. I managed to get it unstuck and it never happened again.

[Ron]

This is the weird part, when I pull the fuse for the low beams (#14) everything functions as it should. Lights switch on and off perfectly. "Everything"???...Double check that the low beams only will work with fuse #14 pulled. If so, that changes everything and it is very wierd!...

If not, try the high beam relay in the low beam's socket.
If no luck, pull fuse #6...

[DeLorean937]

Sorry for the delayed response. I finally had time between work to do some testing.

First off, yes I have the original switch, which I tested and is functioning properly. I disconnected the switch and jumped the 2 leads that control only the headlights.

When I touch the headlight leads to complete the circuit, the headlights activate and stay on, but when i break the circuit, the lights still stay on.

I tried switching the relays to see if it was a bad relay, but it still stays the same. The only way the light deactivate is when I pull the low beam 20 fuse.

Any idea of what this could be? Backfeeding from somewhere?

[Bitsyncmaster]

Sorry for the delayed response. I finally had time between work to do some testing.

First off, yes I have the original switch, which I tested and is functioning properly. I disconnected the switch and jumped the 2 leads that control only the headlights.

When I touch the headlight leads to complete the circuit, the headlights activate and stay on, but when i break the circuit, the lights still stay on.

I tried switching the relays to see if it was a bad relay, but it still stays the same. The only way the light deactivate is when I pull the low beam 20 fuse.

Any idea of what this could be? Backfeeding from somewhere?

Now that is a strange problem. Pull the low beam relay when the problem exits and make sure the low beams go out. Then you know something is feeding the relay coil to keep it energized. I think that relay coil drive comes from the high/low beam switch.

[David T]

First of all you should not be "pulling" on the switch. It is a push on, push on, push off. First push gets you parking lights. 2nd push gets you park and either low or high beams depending on the position of the dipper switch. 3rd push shuts off all of the lights. If your switch does not behave like that the switch is bad. Once you get a switch that works as it should then you can troubleshoot the wiring. When you are in low beams or high beams are you sure? Just because the headlights light up (or not) you may not be on the circuit you think. For an example, many times owners will think there is a big problem with the switch, relays or wiring when, in fact, both low (or high) beam filaments are burnt out. Happens more often than you think. One bulb burns out and is not noticed. What really gets your attention is when the second one burns out and you got nuttin and it's dark.
David Teitelbaum

[DeLorean937]

First of all you should not be "pulling" on the switch. It is a push on, push on, push off. First push gets you parking lights. 2nd push gets you park and either low or high beams depending on the position of the dipper switch. 3rd push shuts off all of the lights. If your switch does not behave like that the switch is bad. Once you get a switch that works as it should then you can troubleshoot the wiring. When you are in low beams or high beams are you sure? Just because the headlights light up (or not) you may not be on the circuit you think. For an example, many times owners will think there is a big problem with the switch, relays or wiring when, in fact, both low (or high) beam filaments are burnt out. Happens more often than you think. One bulb burns out and is not noticed. What really gets your attention is when the second one burns out and you got nuttin and it's dark.
David Teitelbaum


Yes the switch works properly. Low beams are the problem area. Highbeams switch on and off fine when I toggle the selector switch. When I say pulling I mean that the head light switch is in the 3rd position, which all the lights should be off, but headlights and only the headlights stay on. Light filaments are fine because they are new Silverstars.

[Elvis]

When I touch the headlight leads to complete the circuit, the headlights activate and stay on, but when i break the circuit, the lights still stay on.

I tried switching the relays to see if it was a bad relay, but it still stays the same. The only way the light deactivate is when I pull the low beam 20 fuse.


Congratulations, you just reinvented the RAM memory :-)

Sounds like the output of the relay is touching the relay-input somehow.
Melted wire ?

Pull the complete row with the relays out and check the wires to the sockets.
I'd say a Blue-Purple wire touches a Blue-Red wire.

[Ron]

Congratulations, you just reinvented the RAM memory :-)

Sounds like the output of the relay is touching the relay-input somehow.
Melted wire ?

Pull the complete row with the relays out and check the wires to the sockets.
I'd say a Blue-Purple wire touches a Blue-Red wire.:hihi2:
That or something like forgetting that the low beams bulbs come on with the highbeams and the Purple is touching the Blue-Slate wire (same as Flash Switch stuck).

Either way, I still cant see it possible for everything to function correctly with fuse #14 pulled...how could the low beams possibly get power?...and if they did how could they burn w/o the indicator light burning?
:dunno:...this is a good one!

[Elvis]

OK OK again - what exactly happens when you pull fuse #14 ?

First you say then everything works as it should and later you say this resets the light.

a bit weird but cool :-)

Very often we get wrong informations and then start to look for possibilities... :ehh:

you do have a schematic, right ?

[DeLorean937]

Haha yes exactly. With the fuse in, I power the lights on and everything comes on. Then, I try turning them off and everything but the headlights turn off. So to turn them off, i have to pull that fuse.

But...when with the fuse out, I can turn the lights on and shut them off with no issue. Everything works as it should.

Yes i have the diagram and everything is placed as it should be. All connections have been tested and work. The only thing I can think of is that there must be 2 leads touching somewhere

[Bitsyncmaster]

With fuse 14 removed you should not get any low beam power to the headlight. So your blue/red wiring has to be shorting to some other circuit. I bet if you pull the low beam relay it still won't shut off the light after it's on. The wire from the fuse up to the front of the car must be shorting to another wire. It runs up the center consol which is the most likly place it's bad.

[Ron]

Very often we get wrong informations and then start to look for possibilities... :ehh:


+1


After taking another look-
If the Blue-Purple wire is touching a Blue-Red wire, there would not be a problem until the high beams were selected (because the Blue-Purple is dead until then...).
(Maybe it's not RAM but WOM ;-)

=========

Robert, help us help you...
Please start from the beginning. Don't leave anything out like new bulbs, if you had to repair any wiring then, other recent upgrades/repairs, etc. Ya never know...
Elaborate, for example, with "headlights come on" or "work correctly", tell us if it is low beams (outer bulbs only), high beams (all 4 bulbs), both....avoids/catches 'bad' assumptions on either end.

Check if the outer bulbs are actually changing filaments, just stay on when you select high beams, or ?? ....and that the high v/s low filaments are coming on at the correct time in the outer bulbs.

Did pulling fuse #6 make any difference?

Check symptoms once starting off with high beams selected, and then begin all over with low beams selected.

With the headlight switch OFF, if you pull back on the high/low switch, do the high beams come on?

Hang in there!

======

+1 Bitsy

I think pull fuse #14, fuse #6, low beam relay, high beam relay, other fuses one at a time, other relays one at a time, in that order. And maybe the low beam relay before fuse #6....

[DeLorean937]

After 3 days of working i have finally diagnosed and fixed the problem. First off, I want thank everyone that responded to the thread to help me out. Without the team work we have on this site, we wouldnt find solutions to anything. So thank you guys again.

Turns out sometime in the past some had incorporated some house wiring and electrical caps into the circuit. It was spliced in and located under the instrument cluster above the A/C ducting. So without hunting for it and taking half the components I would of never found it. Repaired it back to stock set up with heat shrink tubing and everything works perfectly. Now just to find a properly functioning headlight switch... Thanks again,

-Robert

[DMC5180]

You Gotta love Previous Owner "Cobble-de-gook" modifications. :biggrin: Makes Delorean ownership that much more interesting I guess.

Congrats on the the fix.