TheSamba.com :: View topic - Odd Polarizing Instructions with New Generator

Wed Nov 02, 2005 10:57 pm

I have been having an ongoing charging problem that I have been trying to solve on this forum which I will not go into here but you can read about at this link.

http://www.thesamba.com/vw/forum/viewtopic.php?t=140102&highlight=polarizing

I picked up a replacement generator today which which is a rebuilt Bosch unit from Autolite. I was very confused when I red the polarizing instructions that came in the box. It reads like this:

Quote: Polarizing the Generator

The generator needs to be polarized before the wiring harness is reconnected. You can do this by using 14-guage wire to reach from the battery to the generator. Connect the wire to the battery's Hot terminal then tap the other end of the wire to the Field terminal (DF) of the generator. Remove the 14-guage jumper wire when this step is completed.
Reconnect the wiring harness to the generator, if there is a spark at either of the generator terminals (DF & D+), this suggests the regulator/generator is damaged and should be replaced before the vehicle is started.

If I am not mistaken these instruction are not correct. Shouldn't the generator be polarized by grounding the DF terminal to the generator body and touching a wire from the positive terminal of the battery to the D+ terminal of the generator?

Thu Nov 03, 2005 9:39 am

Yes, you are correct. You polarize by grounding the DF and appling power to the D+.
I have the VW instructions someplace on my web site. I will have to find them and create a link.

Thu Nov 03, 2005 4:06 pm

Yup, that's how Bentley describes it, and shows it on page 25 of the electrical system section. 8)

Thu Nov 03, 2005 4:20 pm

I am in the process of installing the generator and I did the polarization procedure. I have a question. When I touch the wire from the positive terminal of the battery to the D+ terminal the generator acts like a motor and turns as it should. My question is when I polarize the gen. should it turn in the same direction as engine rotation or should it turn the opposite direction? When I polarized it the generator it turned counterclockwise which is opposite of engine rotation. Is this correct? If not could the rebuilder have the D+ and DF terminals on the generator reversed which would explain why the instructions for polarization included with the generator say to polarize to the DF terminal. It does mention in the instructions with the generator installation instructions that many British cars are positive ground that the generator will work in a car with positive ground if the "polarizing policy is followed." Maybe they wired the generator for a positive ground car. If this is the case it could explain why I have been having the problem discussed in my other thread where the generator will work for a short time after I polarize it then stop working until I polarize it again.

Fri Nov 04, 2005 3:52 pm

Installed the generator. Polarized it. The generator does not charge. Repolarized and tested again. Nothing. This is the last Autolite rebuilt Generator I will buy. I am at my wits end and don't know what to do.

Fri Nov 04, 2005 4:49 pm

[email protected] wrote: Installed the generator. Polarized it. The generator does not charge. Repolarized and tested again. Nothing. This is the last Autolite rebuilt Generator I will buy. I am at my wits end and don't know what to do.
When you polarize the generator, does it spin like a motor??
If it does, then the generator is good. You either have a bad regulator, or a problem in the wiring.
Connect your voltmeter to the D+ terminal with no wires connected. With the engine running, momentarily ground the DF terminal. And I mean MOMENTARILY. You should see over 20V with the engine at a fast idle. This is called full fielding the generator. If you do, then the generator is good. If you don't, the generator is bad.

Fri Nov 04, 2005 5:26 pm

Smack the regulator a good one with a screwdriver's handle with the engine running. That one has worked for me twice on 2 different cars after replacing the generator. I assume you changed the regulator when you did the generator?

Fri Nov 04, 2005 8:45 pm

Russ Wolfe wrote: [email protected] wrote: Installed the generator. Polarized it. The generator does not charge. Repolarized and tested again. Nothing. This is the last Autolite rebuilt Generator I will buy. I am at my wits end and don't know what to do.
When you polarize the generator, does it spin like a motor??
If it does, then the generator is good. You either have a bad regulator, or a problem in the wiring.
Connect your voltmeter to the D+ terminal with no wires connected. With the engine running, momentarily ground the DF terminal. And I mean MOMENTARILY. You should see over 20V with the engine at a fast idle. This is called full fielding the generator. If you do, then the generator is good. If you don't, the generator is bad.

Yes it spun like a motor when I polarized it.
I did the test you described and got no reading. That is how I know the generator is bad. I also took it to a local shop that specializes in Volkswagens and they came to the same conclusion. I purchased a Bosch voltage regulator from them and have another generator on order from them also which will be in tomorrow morning.

Fri Nov 04, 2005 8:48 pm

Ace wrote: Smack the regulator a good one with a screwdriver's handle with the engine running. That one has worked for me twice on 2 different cars after replacing the generator. I assume you changed the regulator when you did the generator?

That won't work since the generator is no good.

Yes I did replace the regulator. Twice as a matter of fact and this is my second gernerator. i discussed this in another thread on the Samba.

http://www.thesamba.com/vw/forum/viewtopic.php?t=140102&highlight=polarizing

Fri Nov 04, 2005 9:28 pm

Don`t buy VW parts from Kragen. Only use new Bosch or rebuilt by Bosch. This goes for for ignition parts as well. And don`t buy any brake parts other than VW parts. I have learned this the hard many years ago.

Fri Nov 04, 2005 9:56 pm

You got that right.

Sat Nov 05, 2005 12:49 pm

I haven't asked this question yet but it may be a relevant piece of information to help in determining the cause of my current charging problems.
Shortly before my generator went out and I starting this current round of parts replacement I noticed that the brushes seemed to be sparking excessively and that there was a green glow inside the generator which appeared to be coming from the area of the lower brush so I could not pinpoint the exact point of origin. At this time the generator light had not yet started coming on but I had noticed that it had been taking a little longer for the light to shut off when I started the car. I had just finished doing a tune-up and was checking the timing that, is the only reason I happened to notice.
Back to the generator - When I inspected the generator after noticing the glow and sparking I discovered that the brushes were worn down and in need of replacement, even though I had just purchased this generator along with a new Neihoff voltage regulator 4 months earlier in late June (shouldn't the brushes last longer then that?).
I relaced the brushes and the green glow appeared to go away but in my opinion the brushes still appeared to be sparking more than normal. Shortly after I replaced the brushes within a day or so the generator light starting popping on occasionally. So I cleaned the commutator with sandpaper and the light stopped coming on. A couple days later the generator light came on agian and stayed on. Thjrough testing I determined that the generator was no longer working. This is when my parts replacing nightmare began.

Any ideas as to what may have caused the green glow inside the generator? Has anyone ever seen this before? I mentioned the glow to the guys at the auto parts store and they had never heard of this but of course they are not mechanics or familiar with Volkswagens. The local Volkswagen shop said it was probably overcharging caused by a bad voltage regulator.
During my parts replacment and testing I did find a short to ground caused by a hot wire from the stereo which I repaired. Could this have caused the voltage regulator and generator to fail causing my current set of problems and now I am just getting bad parts?