Radio troubleshooting/options

[slotard]

73 C20, idiot lights rather than gauges (not sure if that matters). A decent mess of wires under the dash.

The radio doesn't seem to do anything at all and I'm trying to figure out what troubleshooting steps to take. Previous Owner doesn't remember it working but isn't sure he tried.

If I get a new one I'd rather not have to hack up the dash. Aux in would be nice. Sound quality isn't all that important.

Thanks for any help.

[motornut]

When testing be sure to bypass the factory plug,some contacts break and get loose

[truckin 79]

Any radio just needs 12v + and ground to power up. Stock delco radio 12v+ is yellow and then ground, if it is a aftermarket stereo then the 12v+ is red(constant) and then you also have to up a yellow wire as well (key on 12v+). You can look on your fuse box and there is a place to hook up accessories like radios and bypass stock wires. Although I would say if you see a stock yellow and black pigtail close by the old radio then I would test it and see if you get 12v. I have used a 18v Ryobi rechargeable battery to test radios in and out of car.

[ray_mcavoy]

Also check to make sure the speaker is still good.

If it's the stock single speaker in the center of the dash, it should have 2 wires connecting it to the radio. Usually black & green or light & dark green. Unplug the connector from the radio and connect an ohmmeter across those 2 speaker wires. Speakers of this era typically had a nominal impedance of 10Ω so the DC resistance (as measured on the ohmmeter) should be somewhere near 8Ω. If you get an infinite reading on the meter you probably have a wire broken loose from the speaker or a bad speaker (open voice coil).