I need some help. I removed the factory radio in my 76 Cutlass Supreme and replaced it with a classic car radio with Bluetooth. When I did, I lost my dash lights on the speedo and gas gauge when I turn the headlights on. Does anyone know why? I thought maybe it was coincidence, so I replaced the headlight switch, but they still don’t work. Looks like the car has a factory amplifier above the glovebox. I’ve checked all the connections I can find and nothing seems loose or disconnected.

 

Did you check the fuse? Is the dash pot turned all the way up?

 

Yes I checked the fuses. And by dash pot, I’m guessing you are talking about turning the headlight ****, and if so, yes I have. Everything else works. Headlights, dome lights, turn signals, high beams, all the idiot lights in the cluster work, everything except the cluster lights that come on with the headlights. I’m wondering if the factory radio had a dimming light on it and it supplied the power for the cluster? There was one harness that didn’t get plugged back in. I’m guessing it’s for the factory amp.

 

The factory radio likely had a dial light that went on with the headlight switch, but it should have been connected in parallel with the dash lights, so losing the radio light should not affect the other lights.

I'm wondering about that connector on the left side of your photo. Historically, the power wire to the radio is yellow, the ground is black, and the wire for the dial light is gray. In later model cars where the radio might have had a clock and/or stored electronic presets, there would have been a red wire that ran constant 12 V to the radio so the presets and clock setting would not be lost when the car was switched off.

In your case, I see a black and a gray wire, but not a yellow. I think the green could have been for a power antenna. Does or did your car have a power antenna that went up and down with the radio power ****?

What's the white wire? Is that 12 V to the radio?

 

That connector is for the front speakers. There was a yellow wire for 12v with key on, black wire (ground), and a grey wire which was also a ground but there was no connector on the radio for it, so it wasn’t really doing anything. The antenna is in the glass, no power antenna.

 

The gray wire is not a ground, its instrument lighting. Double check the fuse and make sure there is power on both sides with the headlight switch on. You should also have 12v on that gray wire with the headlights on.

 

Well that’s weird. I checked the grey wire with my ohm meter and it showed ground the same as the black wire did I believe. Would there be a fuse anywhere other than the fuse block on the firewall?

 

Checking the gray wire with an ohm meter is a fruitless effort because it will read continuity to ground through the other light bulbs. Using an ohm meter on completed circuits is misleading, Use a test light on circuits with power on. No there is but one fuse in the fuse block. The fuse terminals can be corroded and although the fuse may be good it won't pass voltage. The fuse is on the output side of the headlight dash pot.

 

Just an update to this post, I didn’t realize I left he post without the fix. After realizing the grey wire wasn’t a ground, I disconnected that wire. Eventually I found the dash light fuse all the way at the top of the fuse block. It’s a tiny little fuse. It was blown from connecting that grey wire to ground. Replaced the fuse and everything worked as it should. Thanks everyone for the input.

 

Good deal thanks for posting back

 

Well done

 

This solidifies it, I am not ******* with my radio.

 

No guts, no glory!

Long as you understand FACTORY radio wiring colors, installing an aftermarket is not difficult.

 

And since the basic GM radio wiring has been the same since the early 70 until the early 90s, that info is easily found.

 

I don't even use the factory wires for an aftermarket radio outside of the lighting and the power.

 

Factory power wiring almost always works best. New speaker wiring is a MUST!