No AM on stereo
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
It could be the tuner going bad, or as simple as the antenna losing ground connection or losing its ground plane.
Your radio may need to be "trimmed". Pull off the tuning **** and look above the shaft.. There should be a small screw (it is on most GM cars of that era). Set your AM tuner on a distant but somewhat strong station near 1400. Take a small screwdriver and turn the screw until you get best reception. Then it's "trimmed". Of course, if your tuner has gone bad, this won't help.
Hope it's something simple to take care of.
Your radio may need to be "trimmed". Pull off the tuning **** and look above the shaft.. There should be a small screw (it is on most GM cars of that era). Set your AM tuner on a distant but somewhat strong station near 1400. Take a small screwdriver and turn the screw until you get best reception. Then it's "trimmed". Of course, if your tuner has gone bad, this won't help.
Hope it's something simple to take care of.
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
If it's an aftermarket stereo, then it sounds like you have ground plane or electrical ground issues.
I have another fiberglass car...not a Vette, but an Avanti. It recently had a body off reconstruction, and a new stereo/CD player was installed as well as a new universal type antenna. It wouldn't pick up anything for crap due to the antenna not being grounded. I ran a ground wire to the frame, which improved things. Reception was OK, but not great, but no AM. I installed a metal plate for a C3 Vette and grounded that...again, an improvement but not what I think it should have been, but still no AM. Eventually I had to run a 10 gauge wire as a ground and now it works fine.
An antenna self-grounds to a metal car and it makes for a good ground plane. A fiberglass car needs a ground plane added and securely grounded to the frame.
Aftermarket stereos, while they can deliver splendid sound quality, far beyond what originally came in our Vettes, also demand better connections. You should crawl under the back end and make sure your antenna connections are solid. If the antenna has been replaced, make sure it has a good ground.
I have another fiberglass car...not a Vette, but an Avanti. It recently had a body off reconstruction, and a new stereo/CD player was installed as well as a new universal type antenna. It wouldn't pick up anything for crap due to the antenna not being grounded. I ran a ground wire to the frame, which improved things. Reception was OK, but not great, but no AM. I installed a metal plate for a C3 Vette and grounded that...again, an improvement but not what I think it should have been, but still no AM. Eventually I had to run a 10 gauge wire as a ground and now it works fine.
An antenna self-grounds to a metal car and it makes for a good ground plane. A fiberglass car needs a ground plane added and securely grounded to the frame.
Aftermarket stereos, while they can deliver splendid sound quality, far beyond what originally came in our Vettes, also demand better connections. You should crawl under the back end and make sure your antenna connections are solid. If the antenna has been replaced, make sure it has a good ground.
Safety Car
Joined: Nov 2004
Posts: 4,359
Likes: 57
From: Mundelein Illinois
Also check Antenna extension. In the antenna wire there are two wires. The ground (Shield) and a single wire that run through the center of the cable. If this wire breaks you loose AM. FM will still work, not as good, but it will still work. Try running a new extension outside the car and see if that works.
Antenna, can go bad. Plug a new antenna into back of radio and run a ground wire to battery.
If the two above don't work. Now it's the radio.
Good luck
Antenna, can go bad. Plug a new antenna into back of radio and run a ground wire to battery.
If the two above don't work. Now it's the radio.
Good luck
Racer
Joined: Oct 2006
Posts: 396
Likes: 3
From: Buffalo New York
I had the same problem. New radio, so-so FM, no AM. Installed new antenna and cable, now it's crystal clear from both. (note to self: next time, put in the antenna cable before you put the interior back in!)
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Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
Do you have the shielding on your distributor and plug wires? It was there to shield against radio frequency interference.
Is the noise steady or does it increase or decrease with engine rpm's. If it stays steady, it's ignition interference, if it increases with rpm's, it's alternator whine. You can buy filters for that.
It could still be a poor ground plane as well.
Please don't say it's a Custom AutoSound stereo. They're known for such problems.
Is the noise steady or does it increase or decrease with engine rpm's. If it stays steady, it's ignition interference, if it increases with rpm's, it's alternator whine. You can buy filters for that.
It could still be a poor ground plane as well.
Please don't say it's a Custom AutoSound stereo. They're known for such problems.