wiring questions. bad ground?

[Franken Chevy]

I know its not a technical squarebody but I just picked up a 1990 chevy for $400. I have a problem tho. When the head lights and cabin lights are off everything works but when the cabin lights and head lights are on the tail lights blinkers and radio dont work. Any help? Thx

 

[HotRodPC]

I know its not a technical squarebody but I just picked up a 1990 chevy for $400. I have a problem tho. When the head lights and cabin lights are off everything works but when the cabin lights and head lights are on the tail lights blinkers and radio dont work. Any help? Thx

That is wierd cuz those items aren't on the same circuit to the best of my recallection. When you say cabin lights are you referring to the dome light? Dash lights? or overhead cab marker lights?


Does make me think of the headlight switch though. But why would that affect radio? There are a few GMT400 body guys here. Help will be here soon.

 

[ScottyB]

That is wierd cuz those items aren't on the same circuit to the best of my recallection. When you say cabin lights are you referring to the dome light? Dash lights? or overhead cab marker lights?


Does make me think of the headlight switch though. But why would that affect radio? There are a few GMT400 body guys here. Help will be here soon.

Aftermarket radio? Almost sounds as if someone butchered the electrical to put something in there that wasn't there originally. Extra amp or something. I've seen guy cross circuit stuff doing their own work.

 

[Franken Chevy]

Would be dash lights. Yes it has an aftermarket radio in it but it doesnt work half the time. If the radio is on and I hit the any button on the dash the radio shuts off and then turns back on even if I hit the horn the radio flickers

 

[Boone83K10]

then your culprit is the radio. I bet the PO tied into the instrument cluster for power and lighting.

 

[Franken Chevy]

Is there anyway to deal with this while keeping the radio or is just getting rid of the radio the best option

 

[Boone83K10]

you can keep the radio, you just need to get it tapped into a different source than it currently is.

 

[Franken Chevy]

what would you recommend taping into? just an open slot in the fuse box?

 

[89Suburban]

Hopefully somebody can post up some diagrams for you. Retro is GMT400 savvy. Hopefully he can chime in.

 

[Franken Chevy]

ok thx. ill just have to start digging until then

 

[89Suburban]

Any of these help?

http://www.diakom.ru/CAR/GMC/1997/Pickup K1500/SYSTEM WIRING DIAGRAMS/

 

[Franken Chevy]

not really. i just need to know what wire to splice back together and what what to cut into

 

[chengny]

Wiring diagrams for base and "deluxe" sound systems:

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Other than the speaker feeds you are dealing with only 3 wires on the original side of the head unit to chassis wiring connector.

The Chevy yellow wire - main power. It is switched on when the key is in either the run or accessory position. It should go to the red wire on the radio.

The Chevy gray wire - lighting supply. It should go to the orange/white wire on the radio

The Chevy black wire - ground. It should go to the radio's black wire.

If you are having problems when the parking or headlights are turned on, there is probably a short in the illumination wiring circuit (gray- to -orange white). It plugs into the fuse block at one of the "L" sockets. Pull the gray wire from the fuse block and see if it resolves the issue.


Orange/white is the aftermarket standard color for head unit lighting - but without a make/model of the head unit I can't say for sure.

 

[89Suburban]

Thank you Jerry

 

[Franken Chevy]

Ok guys new problem. Radio is wired 100% percent correct I looked at it and ever had a shop look at it but for some reason the tail lights and radio dont work with head lights and cabin lights on..
Any more help?
Thx