FIXED!!!! no gauge lights of any kind.

[78C10BigTen]

So i wanted to post this for anyone having this same issue i did, when i bought my 78 i had no gauge lights at all including the wiper control, radio, heater lights, and (still none) dome light. Totally forgetting the clunky headlight switch issues in my dads 73' as i grew up, i was chasing wires and hunting grounds to no avail. Till today when my brain light popped on and said change the headlight switch because it controls all of those, and TAAADAAA!!! So learn from me, if you have this problem start by changing your headlight switch. Also after that i still dont have a dome light, anybody have suggestions where to look other then obviously the bulb??

 

[Honky Kong jr]

So i wanted to post this for anyone having this same issue i did, when i bought my 78 i had no gauge lights at all including the wiper control, radio, heater lights, and (still none) dome light. Totally forgetting the clunky headlight switch issues in my dads 73' as i grew up, i was chasing wires and hunting grounds to no avail. Till today when my brain light popped on and said change the headlight switch because it controls all of those, and TAAADAAA!!! So learn from me, if you have this problem start by changing your headlight switch. Also after that i still dont have a dome light, anybody have suggestions where to look other then obviously the bulb??

Check your door pin switches. The terminals will fall off at times or simply corrode off.

 

[78C10BigTen]

I was gunna look at them because they were my next obvious thing but i havent mustered up the ambition to pull them apart yet. Do they unscrew so to speak or do you need to take the inner panel off?

 

[1987 GMC Jimmy]

They unscrew out of there, and there's a little connector on the wires of the switch that you just undo.

 

[78C10BigTen]

Thanks ill check them tommorrow

 

[chengny]

Just back them out of the threaded boss in the door jamb. It takes about 5-6 turns to get the threads to release and there is plenty of slack in the wire(s) to allow for that many turns:

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Also, on this:

or do you need to take the inner panel off

If you remove the plastic kick panel to access the wiring, you'll be disappointed. There is nothing behind it except another (inner) steel wall. The wires pass through that inner wall way up - above the kick panel and they are sealed by a wicked tight grommet. Pulling them is a job to avoid :

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As you probably know, the dome light and under dash courtesy light are always supplied with battery voltage on a common circuit. They are activated by closing a switch to ground in the other leg. There are 3 switches that will create that path to ground. The L/R hand door jamb switches - as above - are two of them. The third one is internal to the headlight switch. The rheostat used to control the instrument lighting has a little tab on the end of its sweep arm. The dome light ground switch is located right next to the rheostat. When you rotate the knob fully CW, that tab pushes on the movable contact arm of the dome light switch - and causes it to close. This only a mechanical action - the dash lighting rheostat has no electrical connection to the DM/CTSY circuit.

My point is, for you to have no dome/courtesy lights due to the lack of a ground path, would be unlikely. For that to be the cause, all three switches would have to be bad - and you just installed a new H/L switch. If you twist the knob all the way, do you get a dome light?

If a new bulb doesn't help, I'd check the hot side of the dome light socket (orange wire) for power, before tearing into the jamb switches.

 

[78C10BigTen]

I still have no dome by rotating the H.L. switch. I pulled the bulb and it dont look cooked. Where would i find the orange hot? Im not thinking its a wiring issue being as all my electrical no light issues have been simple and non wire related.

 

[78C10BigTen]

Also thank you all for your replies, i really appreciate the help because when it comes to electrical anything im like a blind man walkin thru NYC lol

 

[78C10BigTen]

Just back them out of the threaded boss in the door jamb. It takes about 5-6 turns to get the threads to release and there is plenty of slack in the wire(s) to allow for that many turns:

You must be registered for see images attach

Also, on this:

or do you need to take the inner panel off

If you remove the plastic kick panel to access the wiring, you'll be disappointed. There is nothing behind it except another (inner) steel wall. The wires pass through that inner wall way up - above the kick panel and they are sealed by a wicked tight grommet. Pulling them is a job to avoid :

You must be registered for see images attach

As you probably know, the dome light and under dash courtesy light are always supplied with battery voltage on a common circuit. They are activated by closing a switch to ground in the other leg. There are 3 switches that will create that path to ground. The L/R hand door jamb switches - as above - are two of them. The third one is internal to the headlight switch. The rheostat used to control the instrument lighting has a little tab on the end of its sweep arm. The dome light ground switch is located right next to the rheostat. When you rotate the knob fully CW, that tab pushes on the movable contact arm of the dome light switch - and causes it to close. This only a mechanical action - the dash lighting rheostat has no electrical connection to the DM/CTSY circuit.

My point is, for you to have no dome/courtesy lights due to the lack of a ground path, would be unlikely. For that to be the cause, all three switches would have to be bad - and you just installed a new H/L switch. If you twist the knob all the way, do you get a dome light?

If a new bulb doesn't help, I'd check the hot side of the dome light socket (orange wire) for power, before tearing into the jamb switches.

Nevermind about the orange hot.... i missed the part where you said at the dome socket lol im sorry

 

[chengny]

I still have no dome by rotating the H.L. switch. I pulled the bulb and it dont look cooked. Where would i find the orange hot? Im not thinking its a wiring issue being as all my electrical no light issues have been simple and non wire related.

The bulb is a 1004 - just a simple single pin lamp. To check for power, you don't need to actually access the wiring behind the dome light. You can do it just by removing the bulb. At the bottom of the socket - right in the center - is a contact. That is the hot side and is connected to the orange wire - in back of the socket. The lamp is grounded through the side walls of the socket. The white wire - that goes to the 3 switches discussed above - is connected to the socket wall on the outside. So, to check the wiring on both sides at once, just put one probe of your meter on the tab at the bottom of the socket (positive) and touch the other probe anywhere on the socket wall.

Your meter should show 12 volts (be sure a door is open or the rheostat is all the way over). If you show no voltage, that doesn't mean there isn't any. It could be a broken wire in the ground circuit (WHT). Make a little scratch through the paint (down to bare metal) in some inconspicuous place near the dome assembly. Check the voltage again. But this time, instead using the socket wall for a ground, use the exposed metal in the scratch you made.

BTW, if you don't have a multimeter, these tests can be done with a test lamp instead.

 

[78C10BigTen]

I dont have a multimeter but can easily get one. Again i thank you for your knowledge of electrical because im completely dumbfounded by it. I suppose i have a few things to try tommorrow

 

[Honky Kong jr]

Also the wiring goes up the driver side "B" pillar there is a connector under/ behind the seat

 

[gpmorgan]

If you get that volt meter you can easily check that bulb. Sometimes looks are deceiving. Or you can apply voltage to it directly from the battery.

 

[78C10BigTen]

If you get that volt meter you can easily check that bulb. Sometimes looks are deceiving. Or you can apply voltage to it directly from the battery.

You are indeed right, looks can be decieving. bought a new bulb and popped it in and god said let there be light!! i feel like a dummy but im glad thats all it was. Thanks to all for the help. Much appreciated.

 

[gpmorgan]

You are indeed right, looks can be decieving. bought a new bulb and popped it in and god said let there be light!! i feel like a dummy but im glad thats all it was. Thanks to all for the help. Much appreciated.

I think we've all been down that road. When it comes to electrical issues, I use the KISS rule that an instructor told me years ago. Keep It Simple Stupid. It seems to work pretty good. Glad you got it fixed.