Weird radio wiring short

[Mikey1989]

My truck had an ancient cd player with no bluetooth that still "sort of" worked - it kept rebooting or just turning off for a while and then back on seconds or minutes later. Seemingly random timing but often enough to convince me to replace it.

 

Well, now the new stereo is doing a very similar thing, but only when I turn the head lights on/off. I wired the stereo into the original radio wire bundle. So this is either the power wire (pink) or maybe the ground (black) is failing? Seems more likely a ground problem, right? But how could this be related to the headlight switch?

[eaglescout526]

Sounds like the illumination wire is in the switched power and switched power is feeding the illumination circuit? 

[gogmorgo]

Radio installs aren’t always done by the best and brightest, even when paid for unfortunately. I wouldn’t trust the wiring at all if I didn’t know and trust whoever put it there. 
Track down where the radio is pulling power from. 
My short bed was a radio delete truck but had a stereo hacked into it. Whoever did it tapped into the cigarette lighter wire for the main power wire with a peel twist and tape and it was loose and intermittent. Fortunately more off than on. They also used the headlight switch wire to feed the illumination circuit instead of the dash lights so the radio illumination wasn’t dimmable, and then they managed to strip too much wire back for their butt splices at the radio itself and taped them together so the two wires were making contact, better contact than the power feed at the cigarette lighter. So if I was driving without the headlights on sometimes the stereo would come on after hitting a bump but wouldn’t last long. If I turned the headlights on when I was driving or with the key off the stereo would always work. But the connection at the cigarette lighter was bad enough it wouldn’t backfeed power anywhere else when I turned the headlights on with the key off while I was sitting parked. 
This is also the same stereo setup where it stopped making noise but was still powered on, so I checked the speaker wires for a short. Theres two pairs of speaker wires at the back of the stereo, one goes left and the other goes right. The one going left is shorted. The only speakers I’ve found are in the doors, so presumably it’s the driver’s door speaker that’s shorted. I didn’t want to deal with it at the time but wanted the stereo back so I just cut the wire to eliminate the short and get at least the passenger side speaker back online, and lo and behold when I snipped the wires to what I thought was the driver’s door speak I got my tunes back. From both door speakers.

Don’t trust the PO’s stereo wiring. Check it all. 

[Ωhm]

9 hours ago, Mikey1989 said:

So this is either the power wire (pink)

 

Radio battery memory voltage (RED/TAN). HOT AT ALL TIMES.

Radio ignition voltage (VIO/ORN). HOT IN ACCY OR RUN.

 

[Mikey1989]

19 hours ago, Ωhm said:

 

Radio battery memory voltage (RED/TAN). HOT AT ALL TIMES.

Radio ignition voltage (VIO/ORN). HOT IN ACCY OR RUN.

 

I took another look and confirmed the radio ignition voltage VIO/ORN is wired to the ACCY OR RUN
Also verified the VIO/ORN is wired to the cigarette lighter (sanity check, should not matter).

And this matches the 1988 wiring guide pg 56.

But the radio battery memory voltage is definitely a pink wire.
The original radio connector plug (with most of the wire harness cut off) is still there (though not in use) and there is a pink wire in the plug but no red/tan wire. 
When I looked at the back of the lcd clock I do see a RED/TAN wire.
So the clock wiring matches the 1988 wiring guide but not the radio wiring.

However, this memory voltage oddity must be a red herring as the issue ought to be with the main power input and not the memory backup.

 

Bottom line: something must be messed up in the VIO/ORN wiring elsewhere that is causing an intermittent power failure? 
For now I'll keep a watch to confirm the issue is indeed associated with the headlight switch operation and never happens otherwise.

PS that 1988 wiring guide is a gold mine!

[Mikey1989]

On 1/4/2025 at 7:47 AM, eaglescout526 said:

Sounds like the illumination wire is in the switched power and switched power is feeding the illumination circuit? 

Looks like the illumination wire is not used if it is the dk blue/lt blue wire still attached to the original radio connector plug. The only other wire still attached to the plug must be the ORN/BLK one shown on pg 59 of that '88 electrical diagram manual.

[Ωhm]

56 minutes ago, Mikey1989 said:

Bottom line: something must be messed up in the VIO/ORN wiring elsewhere that is causing an intermittent power failure?

 

This IGN SW circuit is a known issue. Check for burnt connector C267_A.