Exactly what the title says. My dome light works about 70 percent of the time and then randomly it just doesn’t work. Today for example I was cleaning the door switch for the dome light and got it to work better after cleaning it. Everything was fine then went to turn it on one last time but turning it on with the switch and it stopped working completely no matter what. It did this yesterday as well it wasn’t working when I left to go to the store then got back and it worked fine. Wtf

Ive checked the fuse and cleaned all the grounds as much as possible. I’m very familiar with electrical stuff as I used to be an avionics tech but I don’t understand how something like this that isn’t electronic but just a simple circuit can work for one moment then stop the next.

The only clue I have so far is when it’s not working I’ve checked the power side of the light and it has 12v then as soon as I flip the switch either way to on or door it drops to 0v. I thought maybe it was grounding out but there’s no continuity to ground from the power side. Sucks I can’t get to the wiring because it’s in the roof. The contacts on the connector do have some corrosion but I would think it would just work poorly all the time if that was the problem

 

Check the light housing itself. Its electrical parts are merely thin sheet metal and could easily get deformed / corroded, Also, IIRC, it gets ground through same sheet metal and mounting screw.

 

I checked it out there’s a little bit of corrosion but nothing I would call major. Still has good continuity throughout the whole thing.

I’ve been reading up on the whole buzzer thing. From the way I understand the wiring diagram the dome light can still function in the “on” position without the buzzer installed correct? It just won’t work with the door feature? If I’m mistaken and the buzzer is needed for either operation of the dome light then I’ll have to jump the wires assuming my buzzer is intermittent. Also it’s worth noting that the seat belt wires that go on the buckle have been cut.

 

I went out and checked it again this morning. It has 12v with the bulb pulled out (no load applied) but with the bulb installed (load applied) it drops to 0v. The connector on the inside of the assembly looks like its in rough shape. I can’t seem to get the connector to de pin but I am going to make a custom screwdriver to try and get the contacts out. Does anyone know where I could get replacement contacts? Also if the connector isn’t the problem I’m not sure where to start I really wish I could access more of the harness but it is all inside the roof. Even though it’s just the dome light this is really driving my crazy that I can’t figure it out
I’ll try to post some pictures of this in the next couple days.

 

Black-White wire, the positive side of bulb should have steady 12V. The negative of bulb, (black wire) would have 12V when door is closed and dome light is in "door" mode. Goes to ground (zero) when door is opened or switched to manual on.

There is a diode inside the buzzer required in order to make dome work.






I removed my buzzer because I find it annoying. I replaced that internal diode with one shown below...






Here is my buzzer ...

 

Thank you for all that information that’s very helpful. In one of the wiring diagrams in my manual it shows that the dome light has constant power that doesn’t have to flow though the buzzer, and that the power that comes through the buzzer is only for the “door” function of the dome light meaning you could still manually turn the light to the “on” position.

Oddly enough in one of my FSM’s I have the diagram you provided, and in my other FSM I have this


Per the diagram I shouldn’t need the buzzer to use the dome light in the “on” position right? I understand that the buzzer affects the function of the “door” function. When putting my multimeter to the power side of the dome light and the dome light ground I have 12v with the switch turned to the “off” position or if the bulb is removed it will also have 12v when in the “on” position. But if I have the bulb installed and turn the switch to the “on” position my volts drop to 0v.

 

A broken filament can make intermittent contact and work and not work.............

 

This has been happening between 5 different bulbs the past 6 months. I wish it was that simple though

 

Schematic with On position ia more exact on position will always connect to ground, unless ground wire or connection is bad
A broken filament would never cause zero volt across it.
RonTheBiker, I suspect high resistance on wire from dome fuse to the dome fixture.
Wanna test voltage directly from harness connector (red-wht wire?) with fixture removed? Neg multimeter probe to known good ground. Then put known good bulb between that and ground.
Dome wiring runs up the A-pillar, above door, to rear, then another channel above and behind drivers head. Ribs for topliner go into the channel above door and could have cut the wire.

Also chk P.M.

 

With the dome light removed I checked from Red/white wire to ground and I had 0.05v. When I check the from the dome light connector to ground it has 12v.

 

Just cleaned up all the contacts and everything put it back together still doesn’t work. Then was messing around with the multimeter and out of nowhere it turned on. It was working for about a minute and now it’s back to not working again wtf. Also confirmed that the dome light will still work in the “on” position with the buzzer disconnected, the buzzer only controls the “door” function.

So I’m basically right back where I started although now my connections are a little bit cleaner. I wasn’t even moving around in the truck enough for like a break in a wire to be making contact/no contact. And the bulb was shining bright not like dim as it the ground was bad. Also I’ve already tired a new fuse that doesn’t change anything.

I’m going to try cleaning the ground some more and see if that helps but now I’m wondering if I should try replacing the whole light assembly and see if that’s the culprit.

 

Since the door function and the on function both share the same power source but have separate grounds it has to be a power issue somehow. When the dome light works it works in both positions but when it’s not working it doesn’t work at all.

Tomorrow I’m going to check everything that gets power from the dome fuse and double check the wiring behind the steering column since I know that part of the truck wiring has been messed with a little bit when there was an alarm installed in the past.

 

Well I feel kinda dumb for not figuring this out earlier. But it ended up being the contacts were loose on the connector to the dome light. So I made a tool out of a screwdriver to depin the connector and I made the contacts tighter with some pliers. Now it works perfectly. Also thanks @RAD4Runner for your help and I also copied your setup with the diode so now I can keep my door open with my radio on if I want and still keep the door function of my dome light.

 

Cool!
Now if you have key in ignition buzzer disabled, make sure you have a backup. Mine is adventure-proof, thrown-into-pool-by-drunk-friends-proof.