I've put 3 alternators on an '86 Cutlass Supreme with a 307, and none of them will charge. Battery voltage at alternator BAT post while running, and full-field testing reveals no change. Charge light only comes on when the R's are above about 2000, but the battery runs down even at idle. Anyone seen this before? I sure haven't. My boss is experiencing similar problems with his '80s El Camino, so maybe it's more common than I thought?
Alternators not charging
- Thread starter barncar
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does it have a battery wire only? ther are usually signal wires inc. a field voltage wire. if that's bad you won't charge. just in case, make sure the alternator is spinning the right way.
i have a similar issue with my 85 riviera with a 307, tried several alternators and teh battery still runs down. the alternator will only show like 9 volts at the post when tested...
if you have 12v at the battery and 9v at the alternator(on the main cable) then you either have a bad connection or a bad cable. the side terminal batteries that gm uses suck. they develop corrosion in between the terminals.
New battery a week and a half ago. No output whatsoever from the BAT terminal. Clockwise rotation was specified by my supplier, and that's the way it spins. .02V voltage drop from BAT terminal to battery, so that's decent.
how many wires, and what color/size, are connected to the alternator? you should probably (GM never did anything the same twice) have a main (14ga or so) wire from the starter or battery, a smaller (18ga) field wire (ignition switched power) and a small gauge/indicator wire. the indicator wire may have a diode in it and the field wire should have a fusible link. you need to test any and all wires to the alternator for voltage at ign off, ign on engine off, and ign on eng on. use a test light because i have had circuits show good voltage but they had no amperage due to a blown fusible link or a bad connection.
What model of Alternator do you have? If it is a V belt alternator it is most likely either a 10si or 12si alternator. If it is serpentine ( unsure what the Olds 307 used), it is the later style that I do not know the wiring to. SInce it is likely one of the two si alternators, I will give you some wiring basics dealing with them. There are 3 wires used by GM with this alternator: Red 10 gauge ( with fusible links for overload protection) that runs off the alternator post to the battery, and a plug which has 2 wires: a orange wire that runs to the idiot light on the dash and the red exciter wire that runs from the plug to the post on the back of the alternator that the battery wire attaches to. If all of these wires are hooked up correctly, and the fusible links are not melted, the alternator is bad. Take it back to the parts store and have it tested. I have seen numerous parts store alternators that did not work out of the box. I had the misfortune of having 3 faulty ones from a parts store at one time-I know they were bad because I had them tested before leaving the store!
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