1989 Caravan radio back lighting issue

I am trying to figure out why the back lighting on my radio doesn't work. On the bench the lights work fine.

Looking at these diagrams it makes no sense to me.

Typically in most domestic cars +12v is provided to one side of the illumination circuit when the headlights are on and -12v variable is provided to the ground side via the headlight switch.

From what I can tell in these diagrams the Orange wire is +12v when the lights are on but the Blk/Yel wire is also +12v?

Take a look at the fuse box schematic and see if that makes any sense.

I have already tested the orange wire with the lights on. I get +12v at the radio harness.

The Blk/Yel wire also gets +12v with the lights on???!!?!?

If anyone has any insight into what else I can check let me know.

I'm pretty sure that you're correct on that. It gets the 12v feed, and then a feed for the lighting off of the variable resistor in the headlight switch. That voltage is what dims all the dash lights.

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Originally Posted by cordes

I'm pretty sure that you're correct on that. It gets the 12v feed, and then a feed for the lighting off of the variable resistor in the headlight switch. That voltage is what dims all the dash lights.

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Yes. I am stumped with this diagram. It shows both sides getting +12v which I am getting?

Does anyone have a better wiring diagram? Perhaps this one has errors on it.

Thank you.

It's probably the radio. Do you have a picture of it? Many styles of Chrysler stereos from our era have problems with the display. It's very often cold solder joints. I took apart the Infinity stereo from my 89 Lancer last summer and hit all the joints I could. The stereo worked solidly for about a month. Now, it's intermittent. Very frustrating.

cordes, I did bench test the radio back lighting and it was fine.

I did find the issue. The orange wire on the stereo harness had a damaged pin. The spring part of the pin that presses on the radio pin was busted clean off and not touching the stereo pin at all.

Repaired and working fine now. :)

Yep. That'll do it. Glad you figured it out.