How can you tell if your alternator is bad? - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

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post #1 of 4 (permalink) Old 07-08-2011, 06:10 PM Thread Starter
Join Date: Feb 2011
Location: Florida
Posts: 43
How can you tell if your alternator is bad?

I have a Corvette TPI engine in my 62. Every time I have tried to drive it totally dies pretty quickly. I did the lights test and they do dim in and out when I try it and when I put the ac on it gets even worse. What can I do to test and try to fix it. Maybe the wiring. Thanks
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post #2 of 4 (permalink) Old 07-08-2011, 06:39 PM
Join Date: Jan 2006
Posts: 13,022
Your 1961 used a generator with a mechanical points sets combined with springs and bi metal technology to charge the battery at a whopping 36 A per hour.

Today that won't power a good stereo radio. Your Corvette Mis-Fire TBI EFI system has three onboard computers and an electric fuel pump that will keep the motor from even running without a good battery and a decent CS style alternator that puts out 78 Amps per hour at idle. The CS or one wire alternator is self regulating and doesn't have to be tied into your car's wiring at all (other than as a battery charger). Just a single wire running to the battery and back and your electrical issues are over.

If you are attempting to use a SI-10 (the style used from 1967-79) alternator with your existing external voltage regulator you are going to have issues. Buy a new one wire alternator and bolt it on and then use a heavy size 4 red wire to connect the alternator to the positive pole and the same sized black wire to ground the frame of the alternator to the batteries negative terminal.

Once that is done you can connect everything to the battery and it will stay charged and ready to go at all times (I would get a big one to keep your electrical supply constant).

Big Dave
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post #3 of 4 (permalink) Old 07-08-2011, 06:50 PM
Join Date: Jul 2009
Location: Canada
Posts: 1,506
Dave, the Corvette TPI isn't "TBI". It is either batch fire, or sequential multi-port FI, depending on year. The engine parameters are controlled by one computer with PROM chip.

I would be stunned if they went through all the work of an engine swap and kept the old generator.

Apollo, just pull the alternator (two bolts, and two electrical connections), and take it in to any parts store. They will check it for free.


Two doors, four doors, wagons, and ragtops.
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post #4 of 4 (permalink) Old 11-19-2014, 05:46 PM
Join Date: Nov 2014
Location: Palo Alto, USA
Posts: 14
thanks for the list guys. it'll really help me.

Last edited by Cerpollwepol; 11-25-2014 at 07:33 AM.
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