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Clayso, Master Automobile Technician
Category: Chevy
Satisfied Customers: 880
Experience:  ASE Master Certified Automobile Technician. 30 Years Experience.
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Have an 88 class A motorhome with a 454 Chev. The alternator

Customer Question

Have an 88 class A motorhome with a 454 Chev. The alternator stopped charging the battery. The alt is really inaccessible but I can reach the terminals. Need to be walked through troubleshooting whether it is a problem inside the alternator or outside. On GM I've normally seen a two-pin connector to the regulator plus the BAT terminal. But this one has the BAT terminal and a connector with one pink wire to it. There is 12V at the BAT terminal and it doesn't increase with the engine running.
Submitted: 1 year ago.
Category: Chevy
Expert:  Clayso replied 1 year ago.

Hi There, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience.

I don't have any information on motorhomes, but I do know the charging system that you have. The pink wire should have B+ when the engine is running. The pink wire comes from the gauges fuses and goes to the charge indicator light and the regulator in the alternator. Since you have B+ on the BAT terminal and if you have B+ on the pink wire at the alternator when running and the alternator isn't charging the alternator is defective.

I hope this information is helpful. If you have any questions let me know. You can reply back to me through this thread at any time.

Kindly rate my assistance in a positive manner so I may have credit for helping you.
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Customer: replied 1 year ago.
Does this alternator have an internal regulator? The pink wire is not like the old ones where there was a field connection you could put power on to check charging?
Customer: replied 1 year ago.
I am going to go pierce the pink wire to measure its voltage.
Expert:  Clayso replied 1 year ago.

Yes it has an internal regulator and no on this charging system setup the power should already be there from the fuse. Basically when there is B+ on the pink wire the alternator should charge, the regulator controls the amount.

Customer: replied 1 year ago.
I couldn't pierce the pink wire, but I unplugged it and it has 12V with the ignition on. So based on your comments I guess I'll have to spend the big bucks replacing the thing.... I can't even see how to get in there. Thanks
Expert:  Clayso replied 1 year ago.

You're welcome. The last time I was into an engine compartment on a motorhome I replaced the V belts. I went in through the interior and over the motor, it also seems like there was enough room for me to get under and at the front lower part of the engine. This was a Chevy and about 20 years ago.

Expert:  Clayso replied 1 year ago.

Unplugged is fine, as long as B+ is present. I say the alternator is defective.