You most likely have a bad ground check your grounds for good clean conections and minium splices, ie not cut and put back together. Then do a voltage drop test. with a volt meter hook meter red lead to batt positive and black lead to clean spot on block, watch meter as you crank motor, if you see more than 0.5 volts you have high ressistance. Either wire or conection.
Also i hope you have a fuse on the radio power wire connected to the batt. You should connect radio power to the starter soliniod
with a fuse or fuse link.
Good luck

 

The grounds are good (first thing i checked), it only has this problem at idle. No fuse on the radio- it was 40 bucks at Freds dollar store. It is 15 watts X 4. Now that I think about it, it does have a fuse. Any-who....... The charging system is 31 years old. Looks like my check from the insurance company isnt going to go as far as I thought!

 

Do you have a voltmeter? If not you need one to do any real trouble shooting here. Before I started throwing parts at it I would do a full field test on the alt. Just unplug the connector at the regulator and put a jumper between the B terminal and then skip a slot and put the other end of the jumper in the third slot(terminal). Now you have your alternator putting out all it can. Check your voltage readings at the battery now. you must be careful when you do this test. Make sure the engine is on low idle and do not rev it up. With the alt. fukk fielded you can make up to 18 volts or more if you rev the engine. That might let the smoke out of your stereo, and you know you have to keep the smoke inside it for it to work.

 

Where I live (and shop), for about $100 you could go with rebuilt alternator, regulater, new cables, solenoid. I usually just stop at the parts store and they hook up the charging system tester for free, and tell me what the prob is. Its always a battery prob out here in the hot desert. Average 1 to 2 yrs and they're shot.

 

If your battery is bad, which it sounds like it is, Then the cell that is no good will demand all of the amperage that your alternator can give it, since your alternator supplies current that is in direct relationship with the rpm of the pulley (low rpm=less current and visa-versa), then at idle, your dead cell is drawing all of the available current leaving little for anything else including your radio. I would start your truck and then disconnect your battery, if your truck continues to run then your alternator is functioning properly, if your truck dies then your alternator is shot. Either way, I think you need to replace your battery.

 

I hope your eye is OK.

 

Thanks for the concern, TX wing. My dad gave me a battery form a chipper they retired at work. I am going to put it in there and see if it stops. I changed the voltage regulator to a unit from my mustang (a 79) I think the stang has a voltmeter instead of the light, but either way, the light stopped comming on.

 

Be very careful when disconnecting the cable. For two reasons, one is safety. A shorted cell will be making excessive battery fumes which are explosive and can be ignited by any spark that you make like when disconnecting the cable. The other thing is you may get a voltage spike that will toast a stereo or other electronic items. It is fairly safe in that reguard on the older vehicles but should never be tried on anything with a computer, which is early 80s on.
I left a battery with a shorted cell on a 60 amp charge and forgot about it. About 15 minutes later I hear a very loud explosion and the only thing left of that battery was the bottom and a few plates. I also had a customer once with a chevy pickup who had me check out his charging system and battery. After the tests which included a load test on the battery I tell him he has a shorted cell so he heads down to his uncles Texaco to get a new one. The very next start after he left my shop, that battery exploded and left a big dent in the hood right where my face had been a few minutes earlier. My point is BE CAREFUL!!!. Batterys don't blow very often, but I have seen a few and you could get seriously injured or even killed. And one with a shorted cell is very unpredictable.

 

I for one have know many people that thought they could change
a Battery while the engine was running to put in one that needed
charging up some what. ALL ENDED UP COOKING the alt. Back in the olden days Hell you didn't even need a batt to run the engine like ya do with an alt system. Those little diode kinda cook when getting HOT. But fords where always great for a diode going out.
It WOULD be find as long as you didn't drive at night. To check for a shorted cell open batt caps engine not running look for grayish
color water if none. Turn on the headlight and you will see it bubbling if bad. My 3 cents..
Rich

 

I assume the newer battery done the trick- even with my timing a tad too advanced, she cranks right up every time! I do not know if the voltage regulator helped or not, but it seems that all of my problems are solved.

 

Cool,

I just have to say that I drove my 59 belair about 7 miles home when I bought it, with not battery in it. Boy you sure would't try that with anycars nowdays.

 

My mom once got a new battery installed, and the next day, I had to jump her off.......... odd for a new battery huh? we chalked it up to the door not being shut, and the dome light killed it. Well when she got to work, and cut it off, she had to turn it back on to roll the windows up. No power....... The grond terminal was not making any contact. She drove 45 miles on the alternator in a 92 explorer. Good think it wasnt a chebbie, I hear those alternators go out if you look at em funny.