A Tip For The Files: Alternator Plug

Anonymous-0

Well-known Member
Went to install a water pump on the '97 Sunfire with the 2.2L 4-banger, and as I was preparing to remove the alternator, I noticed that the wires that went to the plug on the alternator were broken...with no insulation left at the plug to tell me which wire went to which terminal.

Thankfully, the 4-wire plug on the alternator only uses the two center terminals. And one wire is red, the other is gray. That's about the extent of the good news. Called a tech line for the company that makes the replacement plugs, and they could tell me that the gray wire goes to the F terminal, while the red one goes to the L terminal. But neither the plug nor the alternator were marked with F or L.

On a wild impulse, I went by the local GM dealership and checked with one of the service advisors...who was formerly a master tech, and who was an instructor at the vocational school until they closed their automotive program in 2009. Ken looked up the wiring diagra, bit it was little help...until he noticed that the F terminal at the alternator was labeled C from the plug on, ond the L terminal was labeled B from the plug on.

And lo and behold, there was a "B" and a "C" on the two center terminals on the plug.

So I connected the gray wire to the C terminal, and the red wire to the B terminal, soldered thm; covered the splice with heat shring tubing, and then found some small diameter split convoluted tubing in the garage to put on the entire harness. AND the car charges properly now.

The terminals on the alternator plug, then, looking at the alternator from the back, are BLANK, B, C, and BLANK...and B is the same as L, while C is the same as F.

_ B C _

or

- L F -


Hope someone finds this information useful; I know I would've had I found it sooner.
 

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