Voltage regulator questions?

[ickmann]

Had an issue with lights dimming and brightening with acceleration and deceleration. Changed out the voltage regulator and stil have a problem. Would this directly mean I have a bad alternator? I don't see what else would be involved..

I'm not electrical system inclined so looking for some help on the issue. Also, with the voltage regulator there are two connections; one three prong plug and a separate single butt connector. I know where the three prong connects to , but What is the other single connection for? I have a '75 FJ40.

Thnx,

Ian

 

[Coolerman]

Well start with the basics.
Clean both battery terminals and the battery cables. Then leaving the cables OFF the battery follow them to their other end. Disconnect them, clean the cable ends and mating surfaces to bare metal. Reattach these ends.

The alternator MUST have a good ground to operate correctly so check that. Also clean the connections on the alternator by removing each wire/plug one at a time cleaning it then putting it back.

Now move to the fuse box. One at a time pull each fuse, clean the contacts where it goes, then clean the ends of the fuse. Carefully bend the fuse contacts in a bit with a pair of pliers to help make better contact.

If you have a battery charger, while the cables are off charge the battery. Now finally connect the battery back and see if you still have the problem. If you do then you need to find a buddy with a meter to measure some voltages while the truck is running.

 

[numby]

Had an issue with lights dimming and brightening with acceleration and deceleration.

Common for stock alternators of your vintage.

Changed out the voltage regulator and stil have a problem. Would this directly mean I have a bad alternator? I don't see what else would be involved..

Try adjusting the voltage regulator (if "points" style).

Also, with the voltage regulator there are two connections; one three prong plug and a separate single butt connector. I know where the three prong connects to , but What is the other single connection for? I have a '75 FJ40.

Connects to a condenser to eliminate radio static from the regulator opening and closing.

 

[Buckwheat]

Toss that alternator & regulator & upgrade to the later 2F with internal regulator. Make sure alternator belt is properly adjusted, in addition to Coolerman's suggestions.