There is a very strange intermittent electrical problem with my '94 850 wagon
Everything works fine, but sometimes when I turn off ignition, the headlights stay on and no way to switch them out. It does not respond on the light switch on the dashboard or whatever. Only way is just drop the cable from the negative battery terminal for at least 3-5 hours.
I was unable to find any system there. Sometimes it stays parked, suddenly turns lamps on and keeps them on.
Pretty rarely it keeps the left turn lamps lit after key is removed.
Very crazy and annoying problem.
I even don't have any idea - where to search for solution.
I've searched forum and web but did not find anything like that.
I'll appreciate for any hint or direction...

 

just your headlights or all of your lights i.e. tailights,parking lights??

 

Headlights only, no corners no tail

 

BTT I have the same problem on my '96 850. Any solution?

 

try turning your day running lights off with a small flat head its to the bottom right corner of the headlight switch see if that helps

 

I have only had the car a few days. Found somewhat of a cure. When the ignition is on the healdights and running lights come on, when the ignition is shut off, they stay on. I havefound that when I shut the ignition off and switch to parking lights, and then back to "off", the lights go out. A "search" told me about the screw. I ground down a small screwdriver this evening, I'll try that tomorrow.

It is 4 am where I am, what am I doing cruising the Net?

P.S. I noticed your fleet listing. I have a '67 Coronet with the 440hp.

 

good luck that would probably only be a semi temporary solution. But awesome on the coronet

 

I don't know the headlight system well enough but it sounds like a relay is sticking on. From going through the headlight wiring diagram it would seem to be the #3 relay under the hood in the fuse box is sticking. Turning to "park" and back to off gives it another chance for the contacts to let go.
Next time the lights stick on, try tapping on the relay and see if the lights go off. Not talking about a hammer here, just tapping to see if it might be the contacts stuck and if they will release.

The headlight switch itself isn't directly connected to the headlights. The ignition key supplies power to the headlight switch, the headlight switch is just off or on but the relay is what takes the signal from the headlight switch and the dimmer switch and actually supplies battery power to the low or high beam. The actual power for the bulb doesn't go through the headlight switch or the dimmer switch, it's just a signal to the relay telling the relay what to do.

 

I should have thought of the relay.


I have two German cars which didn't come with relays, the switch is hot. I have rewired them with relays. My preference is early 90's GM, the relays come with their own mounting bracket.

The Fleet

96 850 wagon, plain jane 190K
90 Mercury Cougar, factory supercharged 93K
87 VW Scirocco, 16V 87K
82 Audi Coupe, mit turbo from 5K TMU
67 Dodge Coronet, 440
64 Plymouth convertible, small block