Voltmeter and Courtesy Light Help

[Shawn Watson]

I've got an interesting situation on my 83 K10 where the voltmeter shows battery voltage regardless of key position and the courtesy lights will only come on with the key in the run position. The passenger side seems to be the only one that works unless that's part of the problem.

Everything seems to work: wipers, blinkers, head/tail lights, well, the gas gauge doesn't move, flicker or twitch when the key is rolled or the tank selector switch is rocked. This is a new-to-me truck so who knows but eletrickery isn't my strong suit.

Any ideas? Oh, although there's a little slop in the cylinder, the actual switch seems like it clicks into each position pretty positively.


Shawn

 

[Grit dog]

I bumped a thread that has some good info and wiring diagrams.
In the electrical section here.

 

[Shawn Watson]

I appreciate that, Grit. I'll give it a good read in the morning. In the meantime, I replaced/adjusted the ignition switch and since I was in there, the wiper switch, headlight switch and dimmer switch.

Same deal; voltmeter shows battery voltage regardless of key position. I think my next move will be to pull the cluster out and inspect the printed circuit board unless you guys have a better idea. I'm definitely reaching here.


Shawn

 

[WP29P4A]

Sounds like a grounding issue. I would check the dash grounds before trying other things. Should be some wires grounded above the e-brake. Do the courtesy lights work when you turn the headlight knob? Do you have a ground strap from the back side of the engine to the firewall? Is the hole where the door contacts screw in rusty?

 

[Shawn Watson]

Sounds like a grounding issue. I would check the dash grounds before trying other things. Should be some wires grounded above the e-brake. Do the courtesy lights work when you turn the headlight knob? Do you have a ground strap from the back side of the engine to the firewall? Is the hole where the door contacts screw in rusty?

I've got two ground wires to that little dude on the e-brake; one for the tank selector switch and the other, I believe to be the courtesy lights. The lights will come on with the headlight switch and the passenger door will kick it on with the key in the run position but not in "off". I'm pretty sure the driver's door jamb switch is out but I don't know if that'll kill everything.

Edit: With a new bulb, I just learned that the dome light will come on when the passenger door is opened with the key off but the light under the dash still won't. I did my best to follow the wiring in a schematic and somehow ended up at the horn relay. Is that a possibility? This is one heck of a frustrating side-track

Edit2: Pulled the cluster and I didn't get lucky with a visible short or blow-up on the circuit board. I traced the circuit from the voltmeter to the connector and got all kinds of lost trying to follow that crap between pages and splices but I did end up with a pink/black wire going to the "courtesy center" and the thing is constant-hot. The black wire to the voltmeter is indeed a good ground.

 

[AuroraGirl]

I've got two ground wires to that little dude on the e-brake; one for the tank selector switch and the other, I believe to be the courtesy lights. The lights will come on with the headlight switch and the passenger door will kick it on with the key in the run position but not in "off". I'm pretty sure the driver's door jamb switch is out but I don't know if that'll kill everything.

Edit: With a new bulb, I just learned that the dome light will come on when the passenger door is opened with the key off but the light under the dash still won't. I did my best to follow the wiring in a schematic and somehow ended up at the horn relay. Is that a possibility? This is one heck of a frustrating side-track

Edit2: Pulled the cluster and I didn't get lucky with a visible short or blow-up on the circuit board. I traced the circuit from the voltmeter to the connector and got all kinds of lost trying to follow that crap between pages and splices but I did end up with a pink/black wire going to the "courtesy center" and the thing is constant-hot. The black wire to the voltmeter is indeed a good ground.

Hm

 

[Shawn Watson]

I haven't really had a chance to mess with it since I started the thread but I do have a full-voltage draw on the battery, the drivers door jamb switch is clearly shot so me thinks I should probably replace that before going any further.

Does that make sense?


Shawn

 

[AuroraGirl]

I've got two ground wires to that little dude on the e-brake; one for the tank selector switch and the other, I believe to be the courtesy lights. The lights will come on with the headlight switch and the passenger door will kick it on with the key in the run position but not in "off". I'm pretty sure the driver's door jamb switch is out but I don't know if that'll kill everything.

Edit: With a new bulb, I just learned that the dome light will come on when the passenger door is opened with the key off but the light under the dash still won't. I did my best to follow the wiring in a schematic and somehow ended up at the horn relay. Is that a possibility? This is one heck of a frustrating side-track

Edit2: Pulled the cluster and I didn't get lucky with a visible short or blow-up on the circuit board. I traced the circuit from the voltmeter to the connector and got all kinds of lost trying to follow that crap between pages and splices but I did end up with a pink/black wire going to the "courtesy center" and the thing is constant-hot. The black wire to the voltmeter is indeed a good ground.

black pink is a hot wire OR Its a wire for your tank switcher switch Im pretty sure

 

[Shawn Watson]

I replaced both door jamb switches yesterday and the driver's side was definitely shot to hell. Now the dome light comes on when either door is opened but the courtesy lamp does not. It's been so long since I had a square that I don't even remember if it's supposed to.

The courtesy lamp only comes on with the ignition in the run position. That's not right, is it?

 

[75gmck25]

On mine the courtesy lights in the footwell, and the dome light all come on at the same time when you open the door. However, my door switches are so rusted that they seldom work reliably.

The simple push button door switches in my ‘75 are also a little different diameter than the replacements I’ve found from LMC, so I can’t thread in a new switch. I may drill the fitting out and replace it with a rivnut that matches the replacement switches.

IIRC, the light on the back of the cab also ties into this courtesy circuit. It seems to be set up so that when you turn on the bed light using the switch on the door frame, you also need to have a door open or turn the headlight switch far left. I assume it is to prevent you from accidentally turning on the bed light when just driving down the road.

 

[Shawn Watson]

I guess I need to figure out why I'm not getting power to that orange wire on the courtesy light unless the headlight switch is rolled or the key in "on."

Ugh, this stuff isn't my forte.

 

[SquareRoot]

The orange wire should be hot all the time. Its fused in the fused block. The lights on/off function is thru the ground. The ground comes from either of the door pin switches or the rheostat inside the headlight switch. Make sure the black wire on the headlight switch has a good ground.

 

[Shawn Watson]

Yeah, I don't flippin' know. Orange is constant-hot, door jamb switches kick on the dome light with the key off and everything with the key on. Courtesy lamp works with the rheostat and with the key on but not with the key off.

I'm either going to have to stumble upon the fix or just let it be for now because I've got way too much to do to be stalled out by a single light. Bugs the crap out of me though, lol


Shawn

 

[AuroraGirl]

Yeah, I don't flippin' know. Orange is constant-hot, door jamb switches kick on the dome light with the key off and everything with the key on. Courtesy lamp works with the rheostat and with the key on but not with the key off.

I'm either going to have to stumble upon the fix or just let it be for now because I've got way too much to do to be stalled out by a single light. Bugs the crap out of me though, lol


Shawn

He just told you waht to check ?

 

[Shawn Watson]

He just told you waht to check ?

Yeah, I did. This isn't my forte but I did. Well, the black from the headlight switch disappears into a tight bundle but all of the headlight functions work so that can't be it, can it.