Interior lights wont turn off

[963500]

the dome and map lights wont shut off. They are on the dimmer setting like as you start the truck for 5 seconds they dim then shut off but just stay on. when I push the door plungers or close the doors the lights go from bright to about half dim. also, I didn’t leave the headlight switch on. now am looking for a wiring diagram to try to track down where the zombie power is coming from. Any searches online for others in the same spot end up with no solution ??

‘96 3500 12v manual extra cab dually.

 

[brucejohnson]

What happens when you rotate the instrument light rheostat from full left (dome lights on) to full right (maximum dim)? Initial thoughts are the headlight switch and/or wiring, especially at the connector.

 

[BigPapa]

I'll second the Headlight Switch and/or Connector. Is the Cargo Light on, too?

 

[963500]

What happens when you rotate the instrument light rheostat from full left (dome lights on) to full right (maximum dim)? Initial thoughts are the headlight switch and/or wiring, especially at the connector.

The interior lights go bright when I turn it all of the way up to the “click.” Anything other than that click and the map and dome light are on the dimmer setting.

 

[963500]

I'll second the Headlight Switch and/or Connector. Is the Cargo Light on, too?

I think I’ll just replace it anyway since its prone to failure. I guess I should have mentioned this but the PO installed aftermarket lights and i’m not sure this third brake light even has a cargo light. Nothing when I twist the rheostat for the cargo light, but all when I hit the brakes. I was going to pull it to check the wiring on the back but I left any sealant back at the shop and dont want to break the seal without it.

 

[BarryG]

Just FYI I do not know about the 96's but certainly the 98.5-2002 the lights were ground switched not positive switched. So your zombie power may really be a zombie ground in that circuit.

 

[963500]

Just FYI I do not know about the 96's but certainly the 98.5-2002 the lights were ground switched not positive switched. So your zombie power may really be a zombie ground in that circuit.

Well, crap. Electronics are a developing knowledge for me. What exactly does that mean? the switch is on the ground side of things vs + side? so I would be looking for a miscellaneous ground contacting on the light side of the switch?
Thanks for the patience

 

[BarryG]

If the 96 is neg switched (and I am not sure that it is) it means there is power all the time to the fixture just no ground, the switch is switching the ground not the positive as you surmised.

Could be a chafed ground wire after the switch or more likely the switch itself. I don’t recall the switch being overly expensive at least in my 01

 

[brucejohnson]

I believe BarryG is correct on the headlight switch being B+, or positive switched for the early Gen 2 Rams with the plunger switch vs. the rotary switch of a later model. They did not have a load relay incorporated for the electrical load of a trailer, so all the current went through the headlight switch and toasted lots of headlight switches, connectors and wiring at the switch. You should pull the switch and carefully check the headlight switch connectors and wiring for signs of heat damage. I had to change more than a few in mine and my son's early Gen 2 Rams, as well as patch up the melted wiring.

 

[963500]

If the 96 is neg switched (and I am not sure that it is) it means there is power all the time to the fixture just no ground, the switch is switching the ground not the positive as you surmised.

Could be a chafed ground wire after the switch or more likely the switch itself. I don’t recall the switch being overly expensive at least in my 01

Ah, that make sense. Okay, I’ll concentrate on the negatives too. Thank you for clarifying.

 

[963500]

I believe BarryG is correct on the headlight switch being B+, or positive switched for the early Gen 2 Rams with the plunger switch vs. the rotary switch of a later model. They did not have a load relay incorporated for the electrical load of a trailer, so all the current went through the headlight switch and toasted lots of headlight switches, connectors and wiring at the switch. You should pull the switch and carefully check the headlight switch connectors and wiring for signs of heat damage. I had to change more than a few in mine and my son's early Gen 2 Rams, as well as patch up the melted wiring.

Thanks. Yeah, I remember replacing the one in my ‘95 way back but it was because of headlights being out. I’ll look into it. Ill also be checking out the grounds and the few accessory lights switches the PO installed.

 

[Seabee]

Might just be a defective door switch...................

 

[brucejohnson]

Might just be a defective door switch...................

Now wait just a minute there...That's too simple...and it just might be the cause... Good call. Most issues do follow the KISS principle and us "degreed" types often ferget that stuff.

 

[Seabee]

I always taught the KISS principle, but rarely comply with it when it is my own rig!

 

[BigPapa]

Yep, I’ve fallen prey to it myself. My daughter and I installed a used stereo receiver I’d taken out of my totaled ’95 in her S10. It just quit working on her way home from work. We checked all the wiring and finally pulled it back out of the dash to check the wiring behind it. The problem all along was a blown radio fuse....

 

[963500]

Well, pulled the headlight switch, moved around some wires and plugged the dome light in.....miraculously fixed. Dome light on when door open and/or rheostat on and off when the door and rheostat off. I’m thinking its either the rheostat is worn and me fussing with it dislodged some residue? or possibly some wire was shorting. no idea. I also discovered something I dont remember from my ‘95....a relay? #5015799aa. Maybe its original and wasn’t replaced in a recall I’ve read about? not sure. maybe the short is in there and moving it around separated the issue? I hate intermittent electrical issues.

 

[Cummins12V98]

Might just be a defective door switch...................

I had that issue on my 98

 

[brucejohnson]

Well, pulled the headlight switch, moved around some wires and plugged the dome light in.....miraculously fixed. Dome light on when door open and/or rheostat on and off when the door and rheostat off. I’m thinking its either the rheostat is worn and me fussing with it dislodged some residue? or possibly some wire was shorting. no idea. I also discovered something I dont remember from my ‘95....a relay? #5015799aa. Maybe its original and wasn’t replaced in a recall I’ve read about? not sure. maybe the short is in there and moving it around separated the issue? I hate intermittent electrical issues.

That sounds great. If the wires and/or terminals didn't appear cooked at the terminal block (plug) and it is now working, just wait to see what happens. Like you said, maybe something was "fixed" just by moving things around.
IIRC the dome switch contacts are darn flakey in the headlight switch. The rheostat is loosely set and kinda springy, rotating with the knob. The ceramic containing the rheostat coil has a cam rise which pushes a wimpy contact together to activate the dome/interior lights. That contact is easily bent just looking at it. A lot of current does pass through it creating potential for stuck contacts, bending them through the heat generated, or if they lightly arc welded themselves and bent one contact too close creating an arcing/loose circuit.

 

[963500]

UPDATE: Electrical gremlin identified and isolated.
All fixed. It was the boost gauge feeder which is in a metal anti chafe wrap was grounding between the e-brake bracket to the top of one of the aluminum dome (relays?) for the blinker or the like. whew. electrical tape fix. Done.
Thanks all for the input.

 

[brucejohnson]

UPDATE: Electrical gremlin identified and isolated.
All fixed. It was the boost gauge feeder which is in a metal anti chafe wrap was grounding between the e-brake bracket to the top of one of the aluminum dome (relays?) for the blinker or the like. whew. electrical tape fix. Done.
Thanks all for the input.

Now THAT is a real curve ball. At least it is resolved.