Power to radio

[Cags70PolaraConvert]

goes out when I step on the gas pedal. Even when in park, at idle all is good. When I give her gas the radio goes out. Any thoughts.

 

[rexus31]

Do you have a Factory Service Manual for your car?

 

[traintech55]

Talk about a weird one. The power supply to the radio is the red wire, the orange one is the dash light. Is this a factory radio? Sounds like the wire is rubbing by the gas pedal, but if this is the factory wiring and mounted in the dash retainers it should be well away from anything it could rub against.

 

[Big_John]

You are having trouble with the ignition and now the radio. You must have some basic electrical problems with this car.... All this stuff is related.

This would be hard to diagnose over the internet...

 

[Cags70PolaraConvert]

i agree about the electrical issues. It all started this year when I added the new manifold and carb. What I noticed before is when I hit the brake pedal power will come back. When I am driving and look at my alt guage it is pinned to the right. When I hit the brake the guage comes back to about 3/4 and the radio powers up. I found some shoddy wiring by the alternator, could the problem be coming from there? As the motor revs it is putting out too much power?

 

[Dobalovr]

Sounds like to me its a Power versus Ground problem. The brake light switch is grounding the circuit somewhere you have a ground to power or power to ground

 

[traintech55]

i agree about the electrical issues. It all started this year when I added the new manifold and carb. What I noticed before is when I hit the brake pedal power will come back. When I am driving and look at my alt guage it is pinned to the right. When I hit the brake the guage comes back to about 3/4 and the radio powers up. I found some shoddy wiring by the alternator, could the problem be coming from there? As the motor revs it is putting out too much power?

It is possible, but unlikely. Before I tell you what to look for, remember the basic rule of electricity, power will always find the path to ground, and all these problems together sound like you have a bad ground somewhere. Check your battery to engine block ground, and your engine block to body ground cables first. Next take a test light and do a reverse check, put the clip on the positive of the battery, and touch the probe to the base of the voltage regulator and see if it lights.

 

[Cags70PolaraConvert]

thanks. Will try that all tomorrow. I agree there must be a ground problem somewhere. Willl check lbulb sockets and all for rust and such as welll. As mentioned a couple of the wires near the alternator don't look so good. Will all this be in the service manual under electrical?

 

[rexus31]

Do you have a Factory Service Manual for your car?

 

[Sixpactogo]

Do you have an aftermarket radio? If so, most of them have a high voltage cut off diode that will shut it down if the voltage gets too high. I had a 70 Challenger that did the same thing at times. Everything would be fine and all of a sudden the amp gauge would peg and the radio would quit. I never did figure out what was causing it but I replaced the voltage regulator and alternator and cleaned some paint off of a couple of the grounding areas like at the regulator to firewall screws and monkeyed around with some of the alternator connections and firewall connections and never had the problem again. Either way, your amp gauge should not be pegged if the battery is fully charged so that is what is shutting down your radio when you step on the gas because the voltage is going above the threshold. Could also be the alternator is faulty and is full fielding and not being regulated. I suspect either the regulator or alternator and more than likely bad connections. I would suspect the engine compartment is the best place to start and would be real surprised if the problem is under the dash.

 

[Cags70PolaraConvert]

Well as Big John said I had some basic electrical issues and thanks to Traintech55 for talking me through most of the issues and the troubleshooting. Man knows his stuff and was able to teach me a few things along the way. Yes I have a FSM downloaded but it doesn't help much if you don't fully understand what you are looking at and you need to learn the difference between and how to use a power tester, multi-meter and a continuity tester. So the list of problems went like this:

1) My mechanic who installed the ECU ignition system removed my voltage regulator. Haven't spoken to him yet so I don't know why he removed it. Old one was returned to me in box of parts. Purchased new one and installed.
2) Although it appeared that 2 wires were running to and connected to my alternator, to the same field clip on the alternator, only one was connected to anything in the wiring harness at the firewall. The other one left the alternator and just ended in taped up wires, not connected to anything. This could have been from when I originally purchased the car, I don't know. Now correctly hooked up to voltage regulator and pigtailed into ECU and ballast resistor. Thanks again Traintech and internet(good diagram).
3) The firewall was not grounded- Thank you Traintech55 for talking me through that.
4) Alternator tested and failed so new alternator purchased and installed.

After all the re-wiring and installations car fired right up. Revved engine and radio stayed on. Mullt-testor showed 14.8 volts at the battery which I was told is good. I still need to take for a test drive to make sure but everything appears to wired correctly and working correctly. Even the ALT guage isn't pinned all the way to the right. So once again thank you all that provided advice and specific items to look at. And thanks to those who offered and provided their services directly. Lets see if this takes care of starting while hot problem.

 

[traintech55]

Well as Big John said I had some basic electrical issues and thanks to Traintech55 for talking me through most of the issues and the troubleshooting. Man knows his stuff and was able to teach me a few things along the way. Yes I have a FSM downloaded but it doesn't help much if you don't fully understand what you are looking at and you need to learn the difference between and how to use a power tester, multi-meter and a continuity tester. So the list of problems went like this:

1) My mechanic who installed the ECU ignition system removed my voltage regulator. Haven't spoken to him yet so I don't know why he removed it. Old one was returned to me in box of parts. Purchased new one and installed.
2) Although it appeared that 2 wires were running to and connected to my alternator, to the same field clip on the alternator, only one was connected to anything in the wiring harness at the firewall. The other one left the alternator and just ended in taped up wires, not connected to anything. This could have been from when I originally purchased the car, I don't know. Now correctly hooked up to voltage regulator and pigtailed into ECU and ballast resistor. Thanks again Traintech and internet(good diagram).
3) The firewall was not grounded- Thank you Traintech55 for talking me through that.
4) Alternator tested and failed so new alternator purchased and installed.

After all the re-wiring and installations car fired right up. Revved engine and radio stayed on. Mullt-testor showed 14.8 volts at the battery which I was told is good. I still need to take for a test drive to make sure but everything appears to wired correctly and working correctly. Even the ALT guage isn't pinned all the way to the right. So once again thank you all that provided advice and specific items to look at. And thanks to those who offered and provided their services directly. Lets see if this takes care of starting while hot problem.

Your very welcome.

 

[Cags70PolaraConvert]

Well after putting everything back neatly and taking it for a test drive the system was only showing 12.6 at the battery when running and the the alt meter in the car was showing discharge. Tested some wiring and found some faulty connections. Thanks to looking back at some previous threads and what I have been taught recently I felt comfortable troubleshooting on my own. This site has a great deal of information between the people willing to help and what has been previously posted. Now charging at 13.6 volts with lights on at idle. The wiring fix has also seemed to help with the difficult starting while hot problem I was experiencing.