The Stovebolt Site Forums The Shop Area The Electrical Bay Alternator problems

Having problems with alternator--replaced the old alternator, started truck--now no output on new replacement alternator. 53 Chev converted to 12-Volt system and new wiring harness before I bought it.

Suggestions on how to start checking for the problem?

Need to find a place to start--thanks, T.K.

First, you'll want to make sure that things are grounded properly. If that's OK, then make sure that you have power to the B+ terminal at the plug for the regulator. Alternators have to have a signal voltage in order to operate. No power at that terminal, aand the altenator won't work.
One more thing, make sure that the battery is fully charged. That can cause a similar problem because the voltage signal to the regulator will be weak. Unlike a generator, an alternator will not recharge a completely dead battery. So it does have to have at least some charge to it to allow the alt to do its job.

tk261,

The alternator need a little kick of power before it does its thing. If your alternator is a SI unit, #1 wire needs to see voltage when you turn the key to the ON position. If you are using a older, externally regulated alternator, the 'F' terminal on the alternator should see power when you do the same thing with the key.

With the externally regulated style, you can actually hear the contacts click inside the regulator (firewall) when you cycle the key from ON to OFF.

If you have a voltage tester, you can see if you get power to this wire when you turn the key on.

There is a little hole to stick a dinky screwdriver in that's located in the back of the case. This would only apply to the SI unit. It will ground the regulator (internal) and put the alternator into the "balls to the wall" mode. If your ammeter is working, it should show a big charge.

I don't recall how to full field a external unit, but I'll bet someone does.

In conclusion, the alternator might not be charging because it isn't being told to..OR, your ammeter isn't functioning and it really is charging...OR, the alternator is bum! These checks should help you figure out what is going on.

If you do have a externally regulated alternator, the voltage regulator could easily be the cause of the problem.

Stuart

Stuart said it well. To full field an external regulated alt. disconnect the connector at the regulator & put a jumper from the red wire term. to the blue one. You should get a fat little spark when you touch it & the alt should charge way over.

Atomarc,
What does the term SI stand for? Thanks

beltfed,

Is this a trick question!

I believe it is French, and my bastardization is " S ystem I nternal"..the little solid state regulator is inside.

Why Delco-Remy would use a tag like that I don't know.

Stuart

I've made my living popping fuses since I was 18 years young and I've lived to retire with never knowing. I will admit that process control and hostile enviroment (nuclear) instrumention was more my bag. Thanks as always.
Hey, I wonder if I could interest "The 3100 Rule" in a small nuclear reactor. oh, maybe 25 Kw, instead of that 3/4 hp motor spinning the generator?

SI = [charging/regulating] Systems Imtegrated

Bill

Bill,

So much for my French!


Stuart