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Wed Nov 18, 2009 8:57 pm

Just bought a 71 bus. has an alternator on it and the generator light stays on. It is wired to an external regulator, but already has an internal regulator. I have tried to bypass regulator but I cannot seem to charge the battery and light does not go off. I seem to keep running in circles and can't fix it. Any suggestions?

Wed Nov 18, 2009 9:15 pm

Do you have the Bentley manual?

Its a must for all bus owners and will give you all the proper directions for doing anything to your bus, whether it be to test your alternator to see if its charging, service your engine, change cv joints, general trouble shooting, etc.
Dont expect someone to just answer your questions for you, youre gonna actually have to work and research the question youre asking. (something that seems rather rare these days, especially the younger people)

P.S.-try the search option because this topic has been discussed millions of times on this site...

Wed Nov 18, 2009 10:49 pm

Your bus and mine are not the same however I think you're wrong on a couple levels here...

All alternators on transporters have external regulators. Get the part number off it and order a new one. They're cheap. Get a new or rebuilt alternator and install it. Check and clean/replace battery and alternator leads. If you hook things up right and the system's charging the light will go out.

This is not difficult once you get to it. So get to it! 8)

Wed Nov 18, 2009 10:57 pm

Quote: Just bought a 71 bus. has an alternator on it and the generator light stays on. It is wired to an external regulator, but already has an internal regulator. I have tried to bypass regulator but I cannot seem to charge the battery and light does not go off. I seem to keep running in circles and can't fix it. Any suggestions?

Buddy - got to get a wiring diagram for your bus and a wiring diagram for how that aftermarket alternator is supposed to be. Then make that happen. You can find wiring diagrams like it was when made in Samba Technical drop down to Wiring. Find someone who sells the same kind of alternator and see if they will give you a copy of the instructions.

Thu Nov 19, 2009 8:00 am

I wired it up according to the diagram but the light still stays on. Could my alternator be bad? When I Disconnect the negative cable from the battery it shuts off. Now sometime through the day yesterday it was wired so that when you DC'ed the battery it stayed running.

Thu Nov 19, 2009 8:18 am

Please use a voltmeter for testing when if alternator is charging, the current can run wild when you disconnect the battery and possibly fry the alternator internally.
If it is indeed an internally regulated alternator you only need a big wire to the battery on the big terminal and the blue charge light wire on the small terminal.

Thu Nov 19, 2009 8:25 am

Which diagram are you using????? You need to use the wiring diagram for your internally regulated alternator. The diagram for '71 Bus (which had the 38amp generator and external voltage regulator) is not going to do you any good, except for locating the blue wire that came off the original voltage regulator that goes forward through your Bus and attaches to your dash warning light. That blue wire attaches to your alternator configuration, you need to figure out where. And do not use any type of external regulator since your alternator already has one.

Thu Nov 19, 2009 1:32 pm

Thanks for the help. I wired it the way it is supposed to go and replaced the belt and that solved my problem.