Ugh. Replaced the alt and the cables. Where does the big red cable run? It was burnt and shredded so no way to trace it. Book says battery, some posts say starter. Currently running to starter but not charging battery.

any definite answers?

also, which fuse should I check?

 

battery + -> really big cable to starter -> not quite so big cable to alternator B+

 

ok, didn't notice the 'not charging' part. there's no fuses in that circuit....

first, charge your battery overnight with a decent battery charger so we have a good base line.

turn the ignition on without starting the engine, does the battery/alternator light come on ?

if not, check the D+ wiring, this goes from the instrument panel to the D+ bolt on the back of the alternator. with the ignition on but engine not started, that D+ terminal should be something less than the battery voltage, maybe 7 to 9 volts, give or take. if its 0V, the D+ circuit isn't working.

if the light DOES come on, start the engine, give it a few seconds to stablize the idle, gently blip the throttle once, and see if the light goes out (it should). if it doesn't go out, the alternator itself is suspect.


BUT, there's another possible problem that bit me once on a high mileage 240, the alternator GROUND wire was defective (corroded entirely through under the insulation). with the engine running, take a volt meter set for DC Volts, touch one terminal to the body of the alternator (if its scuzzy, scratch through the scuzz to get clean metal contact), and touch the other terminal to an engine block ground, like the fuel injection bracket where all the brown wires are... you should read very close to 0V, if you are reading plenty of volts, then the alternator is not grounded. replace the ground wire. also check from engine ground (said fuel injection bracket/rail) to battery - terminal, that too should be very close to zero, if its many volts, the engine block ground is poor.