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Fri Jul 11, 2003 10:54 am

I have a 66 bus that has a good alternator (tests out fine) but won't keep the battery charged. every time i start my bus, i rev the motor to about 3500 rpms and watch my voltmeter. when i do this, i see my voltmeter rise from about 11 volts to 14. it seems like my alternator "kicks in" when it hits this amount of rpms. nobody around here seems to know anything about it. This "trick" has been working fine until today when it didn't work. Has anyone else had this problem? I'm guessing something's wrong in the wiring, but i don't know. it's been converted from a 6 to 12 volt. Any help on this is appreciated. Thanks.
Derek.

Fri Jul 11, 2003 12:00 pm

there isnt much to the wiring on a bus, and if everything else is working as it should, that almost rules out the wiring, except for maybe bad connections. Do you have a 2 wire internally regulated ALT, or the one with 1 big terminal, and 3 smaller terminals with a seperate regulator? If it is the later, you probably have a bad regulator, but.......

First I would double check all of your battery connections, Alt connections, follow the wires and make everything tight. If you dont find have a parts store check the battery, If it is ok, have them check the ALT (and seperate regulator if applicable).

Replace whatever is bad, but should it be the regulator, it is almost impossible to find, and pretty expensive, so it would be better off switching to the 2 wire alt.

here are some diagrams to make sure the wiring is correct

(4 wire) http://www.nls.net/mp/volks/schem/altreg.gif

(2 wire) http://www.nls.net/mp/volks/schem/gen_alt.gif+

Fri Jul 11, 2003 12:01 pm

http://www.nls.net/mp/volks/schem/gen_alt.gif sorry

Wed Jul 23, 2003 9:25 am

Thanks for the help.
Derek.

Wed Jul 23, 2003 3:07 pm

I also had an alternator that did that. When you started the car it would'nt kick in until you reved it up,then it would work fine even at idle. I drove the car for 2yrs like that and never had a problem. I sold the car with it like that. Now i have an oval with an alternator and it does the same thing. I don't drive it because it's under construction. Both alts. were made by Motorolla.

Wed Jul 23, 2003 4:33 pm

I've had a motorola that diddn't do that, so I don't think thats it. Do you have the red light working? An Alt depends on that red lite working to send a signal that it's ok to charge the battery

Thu Jul 24, 2003 8:40 am

you mean the red light on the dash? i notice when i start it sometimes, the red light comes on and then goes off. what does that mean?
Derek.

Thu Jul 24, 2003 2:12 pm

the red light should go on when you turn the key on. Everytime. When you start it, the light should go out. Everytime. On a car with an ALT, it may take like 1100 rpms to make the light go out. If the light isnt working, there is your problem

Thu Jul 24, 2003 7:15 pm

Yes my light was working also. I have had motorolas that did not do this also.

Sat Jul 26, 2003 10:45 pm

If it isn't charging your battery it is the voltage regulator. You have an open circuit in your voltage regulator. You also need your idiot light conductor (wire) to terminate at both the idiot light and alternator terminals for the alternator to operate properly too. Inop voltage regultor = no battery charging.
Very simple repair.
Good Luck
Rick

Sat Jul 26, 2003 10:46 pm

correction on the regultor to regulator.

Sat Jul 26, 2003 11:48 pm

ummm, a 2 wire has an internal regulator, not so simple. You did read the 2nd post right?

Sun Jul 27, 2003 1:22 pm

Remove the 3 screws on top, usually a black cover and you'll find your voltage regulator inside.

Sun Jul 27, 2003 1:42 pm

Also when the idiot lamp illuminates (if all terminations, conductor and lamp are good) the voltage regulator has an open. That is all it does. It checks the integrity of the voltage regulator circuit. Thanks Eric.
Rick

Sun Jul 27, 2003 1:44 pm

That's basic electricity.