Fusible link rating

[nattyphysicist]

are they checking current draw on the field, or just output voltage? voltage checks won't show a rotor with low resistance/ high current draw. you need to do an amperage check on the field (rotor). Take it to an auto parts/supply store, not a tire joint. most of those guys couldn't diagnose their way out of a paper bag, and couldn't fix a sandwich.

Canadian Tire is not exactly a "tire joint". They have a full service shop and parts counter. The alternator testing was automated. They have a jig that spins up the alternator and a computer checks things. Don't know what exactly though. At the same time, the guys who work there aren't exactly useful (most of the time).

[FB71]

the word 'tire' is in their name.... they're a tire joint. basically, you need to find a parts house with an electrical shop. Pep Boys down here has a 'full service' shop, but I wouldn't trust them to change their own underwear, much less anything on my vehicles. The computerized thingy you speak of is fancy version of what we used to call a 'growler'. unless the operator knows what he or she is doing, its useless. I've had parts schmucks at local retailers use one of those, tell me a starter or alt is fine, when I know its failed. I usually wind up showing them how to test it properly (thats what I do for a living). If the fuse doesn't blow with alt disconnected, I'd still suspect the alt.

[nattyphysicist]

Well, my car works fine now but I didn't do anything!

I replaced my fusible link with a 20A fuse. Then I disconnected the white wire from the alt and started the car. Fuse didn't blow. I then shut off the car and reconnected the white wire. Started the car and fuse didn't blow. So now the car runs fine with a 20A fuse. I'm not sure why.

[nattyphysicist]

problem back

After a few months of running without problems, my main fusible link is overloading again.

I've changed the alternator with a used one from a junkyard. Didn't help. Looks like the problem is in the harness, unless anyone has any other ideas. I've eliminated the white wire, so now I think there is a short in the black wire with the red stripe. This wire goes to the "charge" light on the cluster, through a fuse, and then to the positive terminal. I figure that a short between the alternator and the charge light would draw current from the white wire through the alternator. This is assuming that those wires connect inside the alternator.

Can someone shed some light on what switching occurs in the alternator regulator? There are 3 wires going in: white, blk/red, and some other one.

Thanks,
Nat