Radio Backlight / Blinker Problem

[Salvagedcircuit]

Problem:

The one nagging electrical issue left in my comanche is a quiet turn signal blinker and a synchronized blink of the radio backlight. My MJ came with a rats-nest in the center DIN slot as it was clipped off by the PO. He must have used an aftermarket set. I rewired it up for a stock radio connector. I noticed that the main gnd for the radio was melted and I removed as much of that wire as I could find. I added in a new gnd wire from C102 location (driver footwell) to the radio spade connector. My stock radio now functions well, but the backlight on the radio slightly dims with the blink of my turning signal. The backlight doesn't turn off, it just slightly dims. My blinker also does not seem very loud. Here's a video:

 

 

 

Condition:

- I have refurbished all the GNDs like the cruiser54 guides, except for the fuel pump ground.

- I have not touched the c101 connector.

- I currently have LED headlights, led footwell bulbs and incandescent bulbs everywhere else.

- I refurbished the headlight connector 4 months ago with fiberglass pen and dielectric grease

 

Troubleshooting:

-I unplugged the entire front headlight harness via the plug and removed the footwell lights. The blinker sounds exactly the same, not faster or slower. This is essentially a low-load condition, there's no front lights being switched on/off when the connector is unplugged.

-I removed the radio to see if the blinker sound changes. The blinker sound stays exactly the same.

 

I'm not sure what's causing the issue, It's possible I wired the radio wrong, or that the melted gnd wire has shorted to another wire in the wire loom causing unknown issues. Otherwise, I'm going to check for any more stock duct-tape wire crimps in the stock engine bay wiring harness. I previously repaired 2 of them, but there may be more.

 

Any other ideas?

 

[eaglescout526]

1 hour ago, Salvagedcircuit said:

quiet turn signal blinker and a synchronized blink of the radio backlight.

Could be the relay that does the clicking you are after is newer and quieter. As for the synchro blink, well I have noticed my lights do the same but its barely noticeable except on the emissions light and low washer light. I can see them blinking with the blinkers and watch the voltmeter bounce slightly as I have the blinker on. So your issue sounds normal.

[Ωhm]

Does it act the same way with the HAZARD switched to ON?

[Salvagedcircuit]

41 minutes ago, Ωhm said:

Does it act the same way with the HAZARD switched to ON?

I just checked. Yes, the radio LCD blinks when the hazard lights are on, just like above. The radio lcd blink is slightly less noticeable though.

 

 

Well, I was hoping I wouldn't find these. More Duct-tape crimps. I originally thought this was PO work, but I remember reading threads about duct-tape crimps. I wonder how long amc / jeep did this.

 

I finally figured out that orange blob on the wiring harness is some kind of diode bridge that's in line with the thermal sensor on the radiator.

[eaglescout526]

When I tore apart a 4.0L engine bay harness I found that exact diode. If I remember, it’s tied into the AC circuit. 

[Ωhm]

1 hour ago, Salvagedcircuit said:

I just checked. Yes, the radio LCD blinks when the hazard lights are on, just like above. The radio lcd blink is slightly less noticeable though.

 

1 hour ago, eaglescout526 said:

So your issue sounds normal.