Dome light on constantly

[tdwnilla1]

Hey guys, I have a weird one for you all to hopefully help me figure out. Last night I opened the door on my car and my dome light came on as usual and I proceeded to change my original incandescent lamp with a LED i just received ( it is a two contact bulb like the original). I closed the door and the dome light stayed on so I instantly assumed it was the LED bulb and I switched it back to the original shut the door and the damn thing stayed on. What in the hell could have possibly changed just by switching the lamp temporarily or not ?

[Brads70]

Does the door switch look ok? 

[Cudajason]

Hey guys, I have a weird one for you all to hopefully help me figure out. Last night I opened the door on my car and my dome light came on as usual and I proceeded to change my original incandescent lamp with a LED i just received ( it is a two contact bulb like the original). I closed the door and the dome light stayed on so I instantly assumed it was the LED bulb and I switched it back to the original shut the door and the damn thing stayed on. What in the hell could have possibly changed just by switching the lamp temporarily or not ?

did  you bump the dimmer switch and turn the dome light on.

And her where did you get the LED light and what size???

[1 Wild R/T]

Three places to look... First any chance the dash light dimmer switch got twisted fully clockwise?  Second unscrew the door switches & see if it goes out....   Third take a look at the dome lamp to see if it's getting grounded somehow....   

Mopar dome lights are wired with whats called ground side switching... What that means is there is always 12v available but no ground... The door switches provide a path to ground as does the dimmer switch on the dash...

[tdwnilla1]

Yes, metered it and it seems to be functioning properly.

[tdwnilla1]

No bump, Ebay cross to original

[Dakota]

The dome light fixture might be somehow grounding to the roof, possibly triggered by movement when the dome light cover was removed or the light bulb was pushed in.  You might see if you can pull the fixture free of the roof and whether that has an impact on the light running or not.

[tdwnilla1]

Three places to look... First any chance the dash light dimmer switch got twisted fully clockwise?  Second unscrew the door switches & see if it goes out....   Third take a look at the dome lamp to see if it's getting grounded somehow....   

Mopar dome lights are wired with whats called ground side switching... What that means is there is always 12v available but no ground... The door switches provide a path to ground as does the dimmer switch on the dash...

Dimmer switch was the first thing I checked. Disconnected the drivers side door switch and it did not change lamp state however I did not check the passenger side switch. If I remove the dome light assembly from the ceiling the light goes out and when I screw it back to the ceiling it comes back on ect.... so I imagine the ground there is working fine. I did however notice that when I open my passenger door my map light comes on and it does go out when I close the door but zero response on drivers side switch. I have a two wire switch so I am presuming that means no delay in the circuit to check and the door switches are a normally closed contact so just disconnecting one wire from the switch should eliminate it as a problem correct ?

[RUNCHARGER]

The bulb is not supposed to ground through the dome body to the car body. So somehow the wiring or bulb fixture is now contacting the dome body where it is not supposed to thereby going to ground and lighting the light.
The bulb is supposed to ground through one of the switches.

[tdwnilla1]

The bulb is not supposed to ground through the dome body to the car body. So somehow the wiring or bulb fixture is now contacting the dome body where it is not supposed to thereby going to ground and lighting the light.
The bulb is supposed to ground through one of the switches.

So basically with the fixture hanging by just the wires you are saying it should be lit. Forgive me for not understanding it however, I am trying to wrap my head around it. Power has to have a ground to complete the circuit so why would it make a difference as to where it is grounded ?

[Burdar]

It doesn't ground to the roof...it grounds through the door switch.  With the dome light housing hanging from the roof(not attached) it should still function as normal.  The door switch ONLY completes the path to ground when the door is opened.  Your light is somehow grounding through the roof.  That's why it's staying on.

There is ALWAYS power at the dome light bulb.  It will turn on when the circuit is grounded.  The circuit gets grounded by the door switch when the door is opened.  If it got grounded through the dome light housing and roof, it would stay on all the time.

[RUNCHARGER]

Think of it this way. The switch is not on the hot side going to the bulb. The bulb always has hot going to it. So the light cannot always be grounded. In order to light the bulb one of the switches has to complete the ground circuit.

[tdwnilla1]

OK. Right now if the light is just dangling by the wires the light will not light up, it will only light up when it is screwed to the roof. If I am understanding all of this correctly one of the terminals at the fixture must be touching the fixture somewhere somehow and that would be the only reason for a completed circuit when fixture is secured to roof ? Seems to be the only logical explanation given the fact all I did was change the damn bulb.

[tdwnilla1]

Think of it this way. The switch is not on the hot side going to the bulb. The bulb always has hot going to it. So the light cannot always be grounded. In order to light the bulb one of the switches has to complete the ground circuit.

So seeing as my switches are testing correctly with my meter I should be looking for a short in one of my Yellow wires then ?

[RUNCHARGER]

Yes: One terminal of the bulb receptacle is hot all the time. My guess is that the other terminal of the bulb receptacle is now touching the dome light body somehow or the wire on that side has rubbed through and is touching the dome light body.