Hello-

I have a 87 T/A and was wondering if anyone knows which wire does what on the connector that plugs into the alternator. The car was originally a 305 TPI. I have the ribbed style pulley on my alternator. The plug has 3 wires coming from it. Ive recently done a re-wire on my car and my haynes manual is no help for 85-on TPI cars.

Any help greatly appreciated.

Thanks

 

3 wire alt.

 

deadbird- thanks for the diagram...but the wire colors dont match mine. I have 2 brown with white tracer and 1 red coming out of my plug. Is the picture the same thing as I have?

Thanks

 

Wire colors varied a little over the years but, the diagram applies to pretty much all newer style (85-up ? I guess) alts..
IIRC, the alt. harness plug should have the letters (S, L, F) on it as shown at the alt. in the diagram.

 

hey.... im also haveing trouble figureing out where my alternator wires are suppost to go. i recently converted my 89 T/A 5.7L TPI to carb. only thing is, my plug has 2 wires comeing from it. one small and white, the other is twice the size and pink. from what i understand.... the small white one is suppost to go to an ignition activated 12V source, and the big pink one is suppost to go to the heater motor? the big pink one is suppost to detect some kind of current draw so it can adjust its power output. it makes sence to me, but my stupid *** alternator wont charge my battery if i hook it up to the heater motor or not. is it possible the big one is suppost to be an ignition activated 12V source and the small one goes to the heater motor? i have no idea why you would need 3 wires on your alt. plug, technicaly my alternator has 3 wires if you count the one comeing out of the bottom of the alternator. actualy, my alternator did work like that for a while, but then it stopped for some reason....

 

deadbird-thanks for your help, I am going to try and wire this thing up this week using the diagram.


psyte- my alternator has a plug w/ 3 wires coming from it and one heavy gauge wire that bolts to a terminal on the alternator casing. So I guess its really a 4 wire alt.

 

Up to 86 GM used the 10Si alt, after 86 the CS units went into all GM passenger cars. Generally there are 3 wires on the plug if an indicator light is used. Vehicles with only a guage have two on the plug. Both style units will operate on as little as two wires. TG's use a sense lead to sample voltage on a circuit with heavy current draw to minimize voltage drop, but it can be tied to any 12v spot and in most cases not even used.