Rob wrote -
The voltage regulator is a box with a lot of wires coming out of it, either on top of the generator, bolted to the side of the engine compartment, or bolted to the body of the car underneath the rear seat. It's function is to control the current and voltage to the battery and to act as a relay to operate the lights directly at night.
Note: Most of the 6-volt generators and all the 12-volt generators have the voltage regulator under the left back seat (opposite side to the battery). The really early 6-volt models had the voltage regulator mounted on the generator. '71 and '72 alternators had an exterior regulator, and '73 up have the internal one. Much simpler wiring.
The generator regulator has 2-3 wires each side of it, some coming out of the hole at the rear where the harness is; and on the front side of the reg, it has at least one wire rejoining the harness leading up to the front -- instrument indicator light (blue wire I think), and a thicker red one tracking over to the battery via the rear seat support rail -- the actual charging wire for the battery. So -- the regulator should have at least a thickish red wire leading to the battery, plus another thickish red wire joining it from the harness just to the rear of it.
Once the car has started, the generator/alternator supplies power back through the voltage regulator to the battery for charging purposes. The voltage regulator protects the battery from being overcharged by the generator/alternator.
Rob wrote of his voltage regulator failure -
I put in a new battery a week ago, and the regulator under the back seat didn't like it -- started clicking furiously at about 1200-1500 rpm. A voltage check indicated no rise in volts as the rpm increased, and there is evidence of a lot of heat on one spot on the regulator, so that means... Time for a new voltage regulator. I'll have to check out the price of a new one today :-( Probably partly the reason the previous battery expired (though it was about 5 years old anyway so I can't complain -- but I will anyway).
Rotten thing has only lasted 27 years! Talk about planned obselesence! :-) And $72.50 hurts! Hopefully the next one will last 27 years.
It only took about 15 minutes to install the new regulator, and now the volts go up with revs, not down as before -- yeah. One problem fixed. I noticed in looking at the regulator problem that the generator brushes are getting a little low, so that job's in the cards for another day (probably time for new generator bearings too....) Always something -- but you gotta love 'em.
Disclaimer stuff: Rob and Dave have prepared this information from their own experiences. We have not assumed any specialised mechanical knowledge, but we DO assume that anyone using this information has at least some basic mechanical ability.
We hope you find this information useful, but we don't take any responsibility for anything which happens to you, other people, your VW or any other property or goods resulting from your use of this material.
Feel free to print off any of this information for your own use. If you intend to link this material to another site, reprint it, or in any other way redistribute it, please leave the information complete, including this disclaimer section, and provide a link to this Web site.
Last revised 6 May 2004.