Radio problems

[1978 K20]

Hi guys...

Been having issues with my radio (aftermarket.. I did installation never had any issues.)

The problem being when I push on the brake pedal, the radio will sometimes restart (goes black, starts right back up.) Never done this before, and the only variable being that it was hot today. I also noticed that when I press on the brakes, my headlights flicker. I'm thinking either a weak alternator, or weak batteries. Let me know what you think


-John

[Irish_Alley]

sounds almost like you have a bare wire from your radios power from the fuse box. when you press the brakes your touching the bare spot in the wire from the radio to the fuse box causing a short which dims the lights and kills the radio.

[1979C20]

I have this EXACT issue. When I press the clutch on, my fog lights flicker off then on and randomly my stereo resets. I found a bare power wire for my fog lights, my clutch had wore the casing away and it grounded out, and when I pushed my clutch all the way in it would barely touch my stereo wire and it eventually found a way the bare wire. So check for any wires near your brake pedal.

[1978 K20]

Thanks guys... I'll go hunting. I'll keep yall posted

[1978 K20]

Upon further review, nothing was rubbing. I am now noticing that It will also shut off when I have my blinkers on (both sides, and still at random times.) I am thinking I have a short in the rear end somewhere. Any common areas?

I have the constant power for the radio plugged into the fuseblock, and the switched power coming off the factory wiring for the original radio.

I also have some aftermarket gauges plugged into the fuseblock on a switched circut that also flicker when the radio cuts out. so I am thinking that it is something on the switched lead, and not constant power.

Anyone have any ideas??

[1979C20]

Check your battery cables and see how tight they are. And maybe your bauges are grounding out. It sounds like you have a big short and when it shorta it dims lights and turns off radio from lack of power supply.

[Radioflyer]

Check the wires from your tail lights towards the cab that run down the frame. Had a problem on our '79 when a pos wire got exposed but we just lost the tail lights all together then when the fuse popped. Have you ever popped the brake light fuse and replaced it with a heavier Amp fuse? If so it may be robbing the volts from the radio, lights, ect... Other thought is a bad ground in the system.

[Irish_Alley]

have you tried just moving wires around to see if you can repeat the problem

[1978 K20]

Tried moving the wires under the dash, nothing. Today I moved the switched power to a spot on the fuse block, and it seemed to help a little. I am thinking that I am having a short somwhere in in brake light circut. Thats the only thing that would be common between the blinkers and brake lights. I am going to tighten the battery cables and start tracing wiring tomorrow. I'll keep yall posted

thanks for the help so far