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Discussion Starter #1
I get two to six months from a new alternator. The last was two months. I installed a new (in chrome case) 110 amp unit. The generator light on the dash would always give out a low glow. Finially it's on full and I'm running off the battery.

The "fasten Seat Belts" light on the dash comes on and goes of while driving. Sometimes is on constantly. The A/C compressor runs when you set the heater to defrost, this shouldn't be.

I'm thinking of changing the complete engine compartment wiring harness. It's a factory 350 with air, cruise, power steering, power brakes and turbo trans.

Any Ideas?

Margoelky
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If you're going through alts that quickly, you probably are either using Autozone or similar rebuilds, have high resistance in the battery output wire, (burned or corroded terminals on the big red wire attached to the post on the backside of alt,) battery output wire melted, or even a crapped out battery. The light problem and the a/c heater issue could be related, if the output wire has melted and is shorting the other circuits.
 

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Good suggestions on the lead wire and high resistance. High resistance can also come from poor grounds. Make sure you have a complete ground path (no paint under the connections). Battery to engine, engine to frame, frame to body.

It is normal for the a/c compressor to run when in defrost mode. GM designed it that way. It helps to take the moisture out of your interior so your windows don't fog up during cold weather.
 

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Discussion Starter #4
Electrical problems keeps frying alternators on my 77 REPLY

Thanks for the reply and helpful advise gentlemen. The first two rebuilds were with orginal GM new alternators, very pricey. The last was done mail order. A company calles PowerMaster. New chrome case and new guts. The test slip that came with it says "76 amps at idle, 104 amps at 6000 rpm.

I'll remove, clean and reset the ground circuit. And check the leads as far back as I can. That all makes sense.

I'm about ready to buy a new wiring harness and replace, except thats a ton of work.

Thanks again for your help. I'll let you know how it turns out.

Margoelky
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Discussion Starter #5
Electrical problems fry my Alternator(s) - reply

Thanks for the input. As it turns out, the main output red lead from the back of the alternator came loose from the brackets holding it to the fender well. It fell against the headers on the right side of the motor. It is melted in two locations. I would imagine this would cause the high resistance problem mentioned.

I'll see if I can get this as a harness and change. I'll let everyone know how it turns out.

Thanks for all the input. This is an awsome site and club.

MargoElky
Cincinnati, OH
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Discussion Starter #6
Finished changing the Alternator and running new wires from the same. That was lots of fun, the factory puts this big V-8 in your way when your trying to replace stuff.

I installed an new set of three gauges: heat, oil pressure, and voltage.

I no longer have the idiot light glowing, the voltage is positive, and everything humming.

The new chrome case alternator and new gauges look really cool and work well.

Thank you both for your help.

Best regards,

margoelky
 
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