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Headlights won't go off

Big O

Big O

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Hey folks, I'm reposting this thread as I posted it yesterday likely in the wrong area so apologies if you've already seen this. Currently have a 72' Charger Rallye 440, AT w/hideaway headlights that I've had for over 4 years. Last weekend was out taking a cruise and when I pulled into the garage the headlights w/high beam and headlight doors are on and open but the switches are not. I pull the dash switch and nothing happens, hit the floor high beam switch, nothing happens, headlights stay on w/headlight doors open.

So I replaced the floor switch, no change, replaced the dash headlight switch (good times there), no change and all I can do at this point is disconnect the battery or disconnect the headlights when driving and manually roll the doors back down. I saw somewhere someone mentioned something about an instrument panel relay switch which I assume is similar to say the starter relay and assume it's under the dash possibly by the glove box. Anyway, I want to get this fixed and need to lean on some of that Mopar experience out there. Ideas, suggestions? Thanks!
 
Basically, the circuit is complete. The lights go off when the circuit is interrupted (ex. switch )... trace the circuit to see how the lights are getting power. Use the diagram in the FSM to see how the circuit is routed. You started throwing parts on it without knowing where the problem is.
 
As I mentioned on your other thread, it seems the green wire between headlight switch and floor dimmer switch ( being spliced to the headlight doors relay ) which feeds the headlights and trigs on/off the headlight doors relay seems to be hot all the time. There is some short between a constant source with this green wire circuit OR any of the low or high beams wires at forward lighting harness with some constant source, WHICH would reach this green wire circuit via the bulkhead and floor dimmer switch back to the cab.

You could try to discard if the failure is into the cab or engine bay disconecting the forward harness plug from firewall. If light remains on and doors close ( with key in RUN of course ), mostly sure the fail is into the harness. If lights goes off but doors keeps open ( once again, with key in RUN ), the short is into the cab.
 
Last edited:
Crackedback said:
check the door relay. Pretty common that they bleed energy to the other side.
Click to expand...

Right, but what about you turn off the key? the relay gets its source from RUN circuit, so as soon you put the key in OFF headlights should go ( not the doors thought )
 
WileERobby said:
Basically, the circuit is complete. The lights go off when the circuit is interrupted (ex. switch )... trace the circuit to see how the lights are getting power. Use the diagram in the FSM to see how the circuit is routed. You started throwing parts on it without knowing where the problem is.
Click to expand...

Agree, I did, but pretty cheap stuff at this point. I had a headlight switch burn up on another 72 I had and that was a mess and figured at this point wouldn't hurt to replace it as when I got it out, it was original. Thanks for the diagram, I'll run through this and see what I can figure out. Much appreciated.
 
Nacho-RT74 said:
As I mentioned on your other thread, it seems the green wire between headlight switch and floor dimmer switch ( being spliced to the headlight doors relay ) which feeds the headlights and trigs on/off the headlight doors relay seems to be hot all the time. There is some short between a constant source with this green wire circuit OR any of the low or high beams wires at forward lighting harness with some constant source, WHICH would reach this green wire circuit via the bulkhead and floor dimmer switch back to the cab.

You could try to discard if the failure is into the cab or engine bay disconecting the forward harness plug from firewall. If light remains on and doors close ( with key in RUN of course ), mostly sure the fail is into the harness. If lights goes off but doors keeps open ( once again, with key in RUN ), the short is into the cab.
Click to expand...

Thanks! I'll check this as well. Started out with the low hanging fruit and need to go deeper at this point.
 
And since grounds play a huge part in electrical systems.....make sure they are good and especially if you can't find anything wrong with the other suggestions. Don't just look at them and think they are good but take them loose and clean the surfaces they connect to and also the connections themselves.
 
Something melted inside the firewall bulkhead would be my guess. I would not connect the battery until the bulkhead was inspected.
 
devinism said:
Something melted inside the firewall bulkhead would be my guess. I would not connect the battery until the bulkhead was inspected.
Click to expand...
.....I was thinking this as well.....

Do me a favor.....discon the battery and lets take a good look at that bulkhead....
 
Thanks guys for all the input. I'll start digging through this and see where it goes and let you know.
 
Well, 2 weeks later and I'm convinced the car is now possessed. I've checked the bulk head and connections and don't see any evidence of anything fried or disconnected. I pulled the ground connections loose, cleaned them and reinstalled, no luck. Pulled the relays from under the dash for the headlight on, headlight doors, etc. and they all seem to be working. Changed the floor dimmer switch as well as the dash headlight switch again, nothing. They stayed on even when the switches were completely out which obviously there is an open circuit but I don't know where at this point. Anyway, just little update to life with an old Mopar, love it...
 
Big O said:
Well, 2 weeks later and I'm convinced the car is now possessed. I've checked the bulk head and connections and don't see any evidence of anything fried or disconnected. I pulled the ground connections loose, cleaned them and reinstalled, no luck. Pulled the relays from under the dash for the headlight on, headlight doors, etc. and they all seem to be working. Changed the floor dimmer switch as well as the dash headlight switch again, nothing. They stayed on even when the switches were completely out which obviously there is an open circuit but I don't know where at this point. Anyway, just little update to life with an old Mopar, love it...
Click to expand...
Are you saying the headlights stay on even with the headlight switch unplugged?
 
Yeah, the only way they will go off is either I unplug them or disconnect the battery.
 
Big O said:
Yeah, the only way they will go off is either I unplug them or disconnect the battery.
Click to expand...
I'm talking about the switch in the dash. Do the lights still stay on with the dash switch unplugged?
 
Correct. Switch completely removed, ignition off, connect battery cable, and the headlights low and high beam come on, but the headlight doors don't open. If I reinstall the dash switch (headlights come on) and I pull the headlight switch to on position, then the headlight doors do function correctly on and off with the dash switch when either on or off. I'm going to try and pull the bulk head connector and see if there is any evidence of a short there, otherwise, I don't know. I looked over the headlight harness from the firewall to the lights, ground, etc. and and it looks great. When I was under the dash, I couldn't see any evidence of damage on that harness either, but I haven't pulled it from the bulkhead connection. I'm thinking it has to be a short somewhere that is letting current continue to flow directly to the headlights only. When the ignition is off (battery connected) the radio, turn signals, etc. won't come on, it's just the headlights...
 
Bulkhead is a problem on MOST of our MoPars. Leave the battery disconnected and go hunting!
 
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