Radio Troubles Help!
Thread Starter
Racer
Joined: Nov 2006
Posts: 258
Likes: 1
From: Temple, TX
Radio Troubles Help!
Hey guys, haven't posted in a while as I sold my 77 a few years ago and just now recently bought a 74 - 454. I'm having some issues with the radio being that it powers on but will not play any music (radio / blue tooth / CD) until I have the car in 4th gear at about 50-60 mph or around 2500 rpm?? The radio does work when the car is not running and I just have the key on. I've never experienced this before so I'm a bit befuddled. The radio is an aftermarket Kenwood, I pulled it out yesterday and checked all fuses / harness and antenna wire are connected well. I followed the antenna wire all the way to the rear to see if there was anything wrong with it and saw nothing concerning. I've got good power and fuse at the fuse box as well. Any ideas?
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Hey guys, haven't posted in a while as I sold my 77 a few years ago and just now recently bought a 74 - 454. I'm having some issues with the radio being that it powers on but will not play any music (radio / blue tooth / CD) until I have the car in 4th gear at about 50-60 mph or around 2500 rpm?? The radio does work when the car is not running and I just have the key on. I've never experienced this before so I'm a bit befuddled. The radio is an aftermarket Kenwood, I pulled it out yesterday and checked all fuses / harness and antenna wire are connected well. I followed the antenna wire all the way to the rear to see if there was anything wrong with it and saw nothing concerning. I've got good power and fuse at the fuse box as well. Any ideas?
Start the car up and see if the radio works- I betting it's a bad diode or two in the alternator.
Richard
Pro
Joined: Nov 2016
Posts: 729
Likes: 118
From: Kelowna British Columbia
All aftermarket radios have 12 volt constant (yellow)that holds the memory ie clock , radio presets etc. It is probably ok. The red is what is from ignition when car running. Of course black is ground. It is one of these causing your problem. You could put a meter or test light on battery ground and while driving see if you have power on the red all the time like you should. If you do put the test lead clip on positive and drive back home and see if you have ground at radio. One trip and you will know which wire is causing trouble. Then replace it with a good known ground or switched wire.
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
All aftermarket radios have 12 volt constant (yellow)that holds the memory ie clock , radio presets etc. It is probably ok. The red is what is from ignition when car running. Of course black is ground. It is one of these causing your problem. You could put a meter or test light on battery ground and while driving see if you have power on the red all the time like you should. If you do put the test lead clip on positive and drive back home and see if you have ground at radio. One trip and you will know which wire is causing trouble. Then replace it with a good known ground or switched wire.
Let us know
Last edited by Richard454; Sep 17, 2018 at 12:04 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I suspect that the radio power was tapped into the ignition coil positive voltage. At low rpm's, the resistance wire limits current (aka lowers voltage) so that the radio won't really work. Once the rpm's come up, the voltage and current level is adequate for it to play. I could be wrong...there are many possible causes... but check out where power supply for radio was captured.
[disregard if it still has the original radio in the car] Problem could also be a bad ground connection to the radio.
[disregard if it still has the original radio in the car] Problem could also be a bad ground connection to the radio.
Thread Starter
Racer
Joined: Nov 2006
Posts: 258
Likes: 1
From: Temple, TX
Ok guys, got a chance to work on it today and am still having issues. Took power wire off of alternator which didn’t fix the problem. Ended up disconnecting where the power was run for radio land connected straight to battery with an in line 10 amp fuse. This didn’t fix the problem so I ran the ground straight to negative on battery to check my ground. Problem persisted. Then ran ignition straight to battery and this didn’t fix it. I figured this would at least tell me which wire to run down. I did notice the factory wires have a grey wire that’s not connected to anything??
Could this have have anything to do with a new distributor cap and rotor set that we’re just installed?
To recap here here is my problem: radio powers on and can flip through all menus. Sound works fine when car is off and ignition turned on. When car is started, sound is “choppy” with either radio or cd until I get up to about 2500 rpm.
Could this have have anything to do with a new distributor cap and rotor set that we’re just installed?
To recap here here is my problem: radio powers on and can flip through all menus. Sound works fine when car is off and ignition turned on. When car is started, sound is “choppy” with either radio or cd until I get up to about 2500 rpm.
Pro
Joined: Nov 2016
Posts: 729
Likes: 118
From: Kelowna British Columbia
raddio
Grey wire is probably for radio light. All instrument lights are grey I believe. Your distributor aie coil could be the problem. Unlike your first report sounded like radio only worked at certain rpm. Now it seems you are saying it is working but choppy. You need a filter no eliminate alternator or ignition noise. You can buy these at most car audio locations of probably NAPA or something. Put it on the constant 12 volt and should fix your problem. They used to use a capacitor on these cars but it would be dried out and not working
Ok guys, got a chance to work on it today and am still having issues. Took power wire off of alternator which didn’t fix the problem. Ended up disconnecting where the power was run for radio land connected straight to battery with an in line 10 amp fuse. This didn’t fix the problem so I ran the ground straight to negative on battery to check my ground. Problem persisted. Then ran ignition straight to battery and this didn’t fix it. I figured this would at least tell me which wire to run down. I did notice the factory wires have a grey wire that’s not connected to anything??
Could this have have anything to do with a new distributor cap and rotor set that we’re just installed?
To recap here here is my problem: radio powers on and can flip through all menus. Sound works fine when car is off and ignition turned on. When car is started, sound is “choppy” with either radio or cd until I get up to about 2500 rpm.
Could this have have anything to do with a new distributor cap and rotor set that we’re just installed?
To recap here here is my problem: radio powers on and can flip through all menus. Sound works fine when car is off and ignition turned on. When car is started, sound is “choppy” with either radio or cd until I get up to about 2500 rpm.
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Heel & Toe
Joined: Apr 2018
Posts: 22
Likes: 7
From: Vic Australia
I have a similar problem with my stereo.
(retro sound #2) works fine when normal driving but cuts out when idling. An absolute pain in the rear at the lights. I have gone direct from battery with all power and no difference. As soon as I touch the accelerator it works fine.
(retro sound #2) works fine when normal driving but cuts out when idling. An absolute pain in the rear at the lights. I have gone direct from battery with all power and no difference. As soon as I touch the accelerator it works fine.
Drifting
Joined: Nov 2013
Posts: 1,572
Likes: 486
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
Seems like an electrical noise issue getting to the radio and causing it to malfunction. Does the car have the metal covers installed over the distributor area? What about the plug wires? Try running the car in the dark with the hood up and see if you can see any arcing off of any of the wires. Another idea to try is to unplug the antenna connection at the radio and see if that makes a difference with the CD working.
Redvette2
Redvette2
Last edited by Redvette2; Oct 1, 2018 at 04:56 AM.
Thread Starter
Racer
Joined: Nov 2006
Posts: 258
Likes: 1
From: Temple, TX
Fixed the radio!!! Thanks guys for all of your help!!
Problem was new new plug wires laying on the valve covers. Used zip ties to pull them off and radio now works with most if not all static gone. Will put a noise filter on my constant 12v and also buy the shielding for the dist and wires which should clear the rest of it up. Thanks again!!!
Problem was new new plug wires laying on the valve covers. Used zip ties to pull them off and radio now works with most if not all static gone. Will put a noise filter on my constant 12v and also buy the shielding for the dist and wires which should clear the rest of it up. Thanks again!!!
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Fixed the radio!!! Thanks guys for all of your help!!
Problem was new new plug wires laying on the valve covers. Used zip ties to pull them off and radio now works with most if not all static gone. Will put a noise filter on my constant 12v and also buy the shielding for the dist and wires which should clear the rest of it up. Thanks again!!!
Problem was new new plug wires laying on the valve covers. Used zip ties to pull them off and radio now works with most if not all static gone. Will put a noise filter on my constant 12v and also buy the shielding for the dist and wires which should clear the rest of it up. Thanks again!!!