Under dash light

[My78truck]

Okay, all you electrical wire geeks, I need some additional brain power. I have an under dash light that is not working. I am switching to LED, not that that should make a difference.

Under dash light does not come on either with door open or with door closed, ignition off or ignition on and light switch turned to interior lights on which at this point is only dome, but all other on fuse do work (dome, cluster, headlights, cargo, door switches)
Also, lighter does not heat up (although I do not need or use)

I have tested for hot at both courtesy socket and lighter socket & wire connections and it registers power
I have tested for ground at courtesy (all 3 ground wires) and is registering ground present

I know the bulb is okay because I switched the courtesy bulb and the dome bulb (which are the same) and the courtesy bulb inserted in the dome works.

So, if I have power, and if I have ground, and bulb is not bad, WHAT is exactly the problem????? The actual socket/socket connections? Now I know why they charge so much for electrical debunking. This is frustrating......

Thanks

 

[OldBlueDually]

Huh, that's an interesting one. You are using the correct bulb, right? Is it the single pin on the bottom of the light? I think....

Anyhow, what shape is your socket in? Even if it looks clean it may not have good contact, I have had that in the past. I usually remove the socket if possible and curl up a piece of green scotch brite pad and scrub the inside of the socket, and also the pin in the socket. Just to be sure I give the pin on the bulb a quick scrub too.

One issue I had was the socket was not fitting the bulb very well, fixed that with a pair a pliers to lightly close the socket to fit the bulb nice & it worked fine after that. I think in this case the light would flicker when on and it drove me nuts.

Sometimes the spring in the socket is weak too that presses against the bulb, I have had to stretch a few springs and then they worked.

I know you stated you have power and ground but be sure if there is a male/female connector to this socket for power that it is also clean. Clean whatever the socket is connected to also to be certain it has good ground. Connections like that I will clean up and use a dab of dielectric grease on them.

Hope you get it figured out, crap like this drives me nuts.

 

[Dave M]

As OBD said, check the bulb, should be the single contact bulb, not the twin.
The dome lamp uses the twin contact, the courtesy lamp uses the single.

 

[My78truck]

Thanks to both of you. The bulb that came out was a GE 1004 and has 2 contacts, new LED also has 2 contacts and is the correct replacement as suggested by SBL. Socket looks good, I used some sand paper to clean up contact points. Unfortunately it is a plastic socket (unlike dome and cargo) with a metal contact bar at bottom and the ground is up on the side, at very top, of socket and I do not feel it fits in tight. I cannot disconnect the connections from the bulb socket holder as the three ground and hot are not disconnectable, and must be connected permanently down inside the socket connection area. This is what it looks like (pic below). Right or wrong, I throught maybe the bar had lost it spring so I used a washer in the bottom to not only take up space but to rig up a contact bar for contacts. Still no light. So, my choices are that I cut this socket out, go to my bone yard and find a few sockets in what appears to be decent shape and temporarily splice them and see if I can get working. OR, I order from LMC the "Courtesy Light Kit" which is basically 2 courtesy lights. I don't remember having 2 but that is fine. I REALLY do not want to run all these wires again to the door jamb switches, I just replaced those. So I would be paying $25, plus probably $8-$15 shipping, dissecting the lamp holders off and splicing into place. UGH!!!!!

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[OldBlueDually]

Did this particular light not ever work at all, or just one day stopped working?

If you remove that washer spacer you put in there and place the bulb back in while pressing it firmly into the socket and wobbling it does it even flicker? I would do this with the doors closed and the headlight switched turned to interior lighting to remove the door switches like you first did. I almost wonder if the socket itself is just shot, or not making good contact with the bulb pins on the sides for ground?

The kit may be your next option, then at least you know it is all new! However, if you would have to replace that harness anyhow have you traced all wires to be sure there is no fraying or cracking in the wire sheathing, or a bad connection somewhere else?

 

[82sbshortbed]

I don't have dome or courtesy lights. I'll be watching to see how you fix it and if that light pack works from lmc. Good luck, I hate fixing electrical ****. Lol

 

[My78truck]

OBD, yes I remember it working at one point in this truck's 40+ year life. Why I haven't before now, I looked in my original owners manual and it states that "courtesy" bulb is a 1003, NOT a 1004. The 1003 bulb has a single contact. So, I am going to go get a 1003 bulb tomorrow and see if this remedies the situation. I will feel SO stupid if it does. I have spent numerous hours trying to figure this out and if it is the bulb...........UGH!!!!!

Stay tuned.

 

[Dave M]

I went out to check my lamp for you, guess what, the bulbs blown !

 

[Dave M]

But now it's fixed with a new bulb.

 

[Turbo4whl]

The socket shown in your picture is for a single contact bulb.

 

[My78truck]

Thanks for trying Dave.

My dad was a mechanic by trade for many years and is now retired. He gave me his 2 tall-stacked tools boxes FULL of Mac Tools. Tools have always been my play toys. So, being a mechanic he keep EVERYTHING, old, new, blown, pieces, bits, gaskets, this, that and everything else. So, I thought to myself, SELF, what are chances you can find a bulb in that mess that has a single contact. My hopes were not high, BUT as luck would have it, there is was. NOT a 1003, but a bulb with a single contact and the same size base as what I needed. so I though, I will just try it quick just to see. So, I toddle out to the truck, in the dark, insert the bulb and...........there was light!!!! I am past flabbergasted and incredibly mad at myself. I feel soooooooooo stupid!!!! I have spent countless hours trying to figure this out and there it is - light.

So, everybody has my permission to tell me I am a stupid A**!!!! because I deserve it.

Oh, and Dave, make sure the bulb is a SINGLE contact.

 

[Dave M]

Thanks for trying Dave.

My dad was a mechanic by trade for many years and is now retired. He gave me his 2 tall-stacked tools boxes FULL of Mac Tools. Tools have always been my play toys. So, being a mechanic he keep EVERYTHING, old, new, blown, pieces, bits, gaskets, this, that and everything else. So, I thought to myself, SELF, what are chances you can find a bulb in that mess that has a single contact. My hopes were not high, BUT as luck would have it, there is was. NOT a 1003, but a bulb with a single contact and the same size base as what I needed. so I though, I will just try it quick just to see. So, I toddle out to the truck, in the dark, insert the bulb and...........there was light!!!! I am past flabbergasted and incredibly mad at myself. I feel soooooooooo stupid!!!! I have spent countless hours trying to figure this out and there it is - light.

So, everybody has my permission to tell me I am a stupid A**!!!! because I deserve it.

Oh, and Dave, make sure the bulb is a SINGLE contact.

No worries mate, glad you SAW THE LIGHT and didn't have to drop $30 + bucks on a light kit unnecessarily.

 

[Grit dog]

@My78truck, I had the exact same saga except opposite.
After hours of chasing down a “short” that was intermittently making the dome light stay on, I removed the cargo light bulb to take apart the cargo light and look for a short to the dome light.
Then realized someone put a single contact bulb in it in place of a 2 contact bulb. Literally a 5 minute fix, or never an issue at all if someone didn’t put the wrong ******* light bulb in it!

 

[Snoots]

Thanks for trying Dave.

My dad was a mechanic by trade for many years and is now retired. He gave me his 2 tall-stacked tools boxes FULL of Mac Tools. Tools have always been my play toys. So, being a mechanic he keep EVERYTHING, old, new, blown, pieces, bits, gaskets, this, that and everything else. So, I thought to myself, SELF, what are chances you can find a bulb in that mess that has a single contact. My hopes were not high, BUT as luck would have it, there is was. NOT a 1003, but a bulb with a single contact and the same size base as what I needed. so I though, I will just try it quick just to see. So, I toddle out to the truck, in the dark, insert the bulb and...........there was light!!!! I am past flabbergasted and incredibly mad at myself. I feel soooooooooo stupid!!!! I have spent countless hours trying to figure this out and there it is - light.

So, everybody has my permission to tell me I am a stupid A**!!!! because I deserve it.

Oh, and Dave, make sure the bulb is a SINGLE contact.

Kaka occurs. Laugh about it and have a beer.

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[My78truck]

Thanks to all of you for your help, and your empathy. This is truly a live and learn.