Another alternator issue


Active Member
How can i make this $%#@! alternator turn on ?

Just replaced the voltage regulator, and now no charge. Volt light does not come on with key, but i have the resistor bulb set up so that isn't a factor. Gauges fuse is good, I have grounded the brown wire at the alt. connector and the Volt light will turn on. I've removed the alternator and had it tested at O'Reilly. Watched the guy do it twice, passed both times, all 3 parts of the test. I have confidence in that. The alternator was working prior to replacing the VR, but voltage was constantly ranging from 13.8-14.5
Everything was working fine before this (aside from the VOLT light, it's never lit up like it was supposed to)
Down time was 1 day.
I've pulled the alt. back apart to check my work, and found nothing. Even compared it to a YouTube video to make sure it was done correctly, which it must be since it tests good off the car.
What can i do to make this turn on, i don't know where else to look.
Sounds like the alternator harness connector is bad. Rig up a small 194 bulb with wires on each leg. Make it so that one of the wires can be attached to the battery + terminal. During these tests make sure that the hot lead to the battery can't short on anything.

Unplug the connector from the alternator. Connect long bulb lead to the + battery terminal. Key-on, engine-off.

Can test the bulb by grounding the short lead to any ground point (alternator body works). The bulb should light up.

Now connect the short lead from bulb to the L terminal on the alternator connector. The bulb should light up. If not then the alternator is bad.

If the bulb lights up then start the engine. Again with the short bulb lead on the L terminal the alternator should start to charge and the bulb should be off. If not then the alternator is bad.

If the above tests work as described then the harness connector to the alternator is bad. If you end up replacing the harness connector it is best to also wire up the F terminal and even better to also wire up the S terminal. That is the best way to wire the alternator.

Thanks for that info. I found and did pretty much the same thing last night after finding a thread on another forum on how to "manually excite" the darn thing.

So, what i've been able to confirm is that the L terminal in the new VR is touch and go. If i simply connect either the cars harness connector to it, or a small alligator clip it will not work. But in using the 194 bulb as an identifier when it was making a connection, i was able to figure out that by side loading the L pin on the ALT, the bulb would light. Doing so of course allowed the system to work, and the ALT charged.

Success ! While home for lunch swapped out the VR today ( Oreilly BWD #R926 ) While i was there i popped on a new rear bearing (National 100CC4)
Reinstalled ALT back onto the car ( i have this down to about 3 minutes) and BAM ! Just like that charging 14.4 like it's supposed to. Friggin new parts... GRRRRRR

Thanks again for the help