TheSamba.com :: View topic - how to check alternator and external voltage regulator

Mon Sep 15, 2008 5:20 am

Hi I have a bosch 043903023A alternator with an external voltage regulator. [says motorola on top of it]. I was wondering how can I check both to see if they are ok.
I have been having problems with the lights getting really bright then going back to normal. I checked the battery with a voltmeter and am getting 12+ on battery and when I hook up to the B+ on the alternator I get 14-16. [even higher when I rev up the motor to around 2500-3000 rpms.
I was wondering what is the correct way to check both. I also was wondering where the brushes are located on the alternator to check them also. On the bosch 043903023A alternator are the brushes on the bottom.

Or I could be wrong on both, it might not even be the alternator or regulator? Possibly a ground problem?

73 super beetle motor in a 73 Ghia.. external voltage regular is on the left side of the engine compartment.

Barry
Thanks Barry

Mon Sep 15, 2008 5:45 am

You have a Bosch alternator and Motorola regulator? I thought you weren't supposed to mix those.

043903023 Motorlola Alternator goes with 043903803 Motorola regulator.
043903023A Bosch alternator goes with a 043903803A Bosch regulator.

Mon Sep 15, 2008 1:07 pm

glutamodo yes that is correct. I wonder if that could be part of the problem?

Barry

Mon Sep 15, 2008 4:36 pm

Hum talked to a friend of mine who is good with electrical stuff and he said it sounds like the regulator.
I told him that when I rev it up the alternator output will go up to 16-17 volts. He said it sounded like the voltage regulator was not dropping the voltage back down to 14 like it suppose too.

Any comments?

Any sugguestion on where to get a good regulator?

Barry

Mon Sep 15, 2008 4:43 pm

Yeah I agree the regulator is either bad or mismatched - probably both.

Genuine Bosch regulators for that alternator have gotten expensive....

http://www.busdepot.com/details.jsp?partnumber=043903803A

I've noticed el-cheapo aftermarket ones regularly on eBay. This is not a VW part so I don't feel bad about posting a link to the auction:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230290562982&

-Andy

Mon Sep 15, 2008 9:32 pm

Thanks glutamodo

Fri Sep 19, 2008 7:32 pm

Replaced the voltage regulator today and so far no more problems. When I check the voltage at the alternator it around 13-14 volts even when reving up the motor..

:D

Sat Sep 20, 2008 3:09 am

How much did you end up paying and where did you get it?

jim

Tue Sep 23, 2008 7:42 pm

Sorry Jim,

I just now check the messages. I ended up buying a cheap one at advance auto for now.[$29.00] I also bought a used original off of the samba. That way I will have a back up if this one goes out.

Barry