Aftermarket Radio help?

[Jay P]

Was the factory harness for the stereo untouched when you started? If so you either have the wrong harness or you didn't do the coding right from the harness adaptor to the new stereo adaptor. No wires need to be cut to convert the stereo system from the 3 piece monstrosity to a normal one piece head unit. If you are having problems with the HVAC now, I would start at the source and check the connections on the HVAC control unit.

A wire could have been pulled loose when you were removing the old stereos control head unit since you have to partially pull out the H
VAC controls to remove the head unit. Everything you need to make your stereo work properly is in the 3 cable connectors clustered together in the stereo amp under the dash. all you need to do is connect your new stereos pigtail to the aftermarket harness adapter and then plug those 3 connectors from the old amp into the new single harness adapter, it's that easy.

The proper harness adaptor will have the wire coding on it and you just match it up to the wire coding to your new stereo's owners manual (some wires may not be used).

These are the 3 cables that came out of the power amp/brain of the factory stereo found under the dash on the drivers side. These are the 3 you want to plug into your new harness adaptor.

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I didn't cut the factory harness I bought the wire adapter for the 88-94 gm trucks and saudered it to the wires of my stereo made sure I matched all the right wires together and everything. So at this point I'm stumped and I'm most likely gonna have to check my truck with a test light later today.

 

[Jay P]

Update I used a test light and checked all my fuses are intact but I discovered when two wires are unplugged and I'm not sure where they go and when I touch the light to the fuse box under the dash the interior lights go completely off

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[Jay P]

Update I used a test light and checked all my fuses are intact but I discovered when two wires are unplugged and I'm not sure where they go and when I touch the light to the fuse box under the dash the interior lights go completely off

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Top image is the two unknown wires. The bottom image is where I touch the light and it completely goes off

 

[Jay P]

Update: double and triple checking all the wires under my dash there was a small ground that was loose and now everything works fine

 

[joep88cheyenne]

Yeah those little grounds will do that to ya. If it was flaky as long as the other unit wasn't running it had a "good' ground but when you turned it on the ground was not sufficient to hold the current. BTW I also have an 88, it is a Cheyenne 2wd and live across the lake from you. IM me if you want to meet up.

 

[Sleeper Van]

All I unplugged was the connections at the bottom of the radio unit.

It sounds like a bad ground and a crossed wire. Just because the colors matched up doesn't mean that they go together. I had a similar situation with a Buick. It turned out to need an additional ground and the wire for the dash lights was different than the wiring instructions. I'd start with the wires for the auxiliary lights/dash lights. Disconnect those first. They can cause the issues you are having because of the lights in both of them. Then add a new ground to the head unit case to a GOOD ground. If these don't work after checking everything else I'd disconnect the new head unit and then connect one wire at a time and see which one is causing your problems. I know that this sounds like a dumbass way to check but with a new stereo system with all the wires it's probably the fastest way to fix your issues. Also after you disconnect the head unit try everything that you were having problems with. It might be a wire you unplugged without even knowing it! Last thought, did you Plug in the antenna? That is also a good ground. Good luck.

 

[Sleeper Van]

It sounds like a bad ground and a crossed wire. Just because the colors matched up doesn't mean that they go together. I had a similar situation with a Buick. It turned out to need an additional ground and the wire for the dash lights was different than the wiring instructions. I'd start with the wires for the auxiliary lights/dash lights. Disconnect those first. They can cause the issues you are having because of the lights in both of them. Then add a new ground to the head unit case to a GOOD ground. If these don't work after checking everything else I'd disconnect the new head unit and then connect one wire at a time and see which one is causing your problems. I know that this sounds like a dumbass way to check but with a new stereo system with all the wires it's probably the fastest way to fix your issues. Also after you disconnect the head unit try everything that you were having problems with. It might be a wire you unplugged without even knowing it! Last thought, did you Plug in the antenna? That is also a good ground. Good luck.

I wanted to add that if everything that was giving you problems goes away after you disconnect the head unit then you know that it's in that unit. If everything is still not working check everything in the area of the Radio and look for a loose wire or a plug that is loose. Did you add any new light's, led bulbs or anything else at the same time as the new radio? Led lights can cause real problems with different systems on the truck. I found out the hard way, just FYI.

 

[Jay P]

I wanted to add that if everything that was giving you problems goes away after you disconnect the head unit then you know that it's in that unit. If everything is still not working check everything in the area of the Radio and look for a loose wire or a plug that is loose. Did you add any new light's, led bulbs or anything else at the same time as the new radio? Led lights can cause real problems with different systems on the truck. I found out the hard way, just FYI.

I plugged in the antenna. There was a loose ground under my dash. One I wired it back up everything works fine now. Doesnt drop below 14 Volts

 

[GMCTRUCKS]

I'm glad it's all good now but when you wrote that you put a ground on the dash I was thinking he might want to use a better ground like one of the bolts to the frame or body and yes a bad ground can mess you up big times.