TheSamba.com :: View topic - Generator Light and Brake light brightnes changing with idle

Mon Sep 17, 2012 12:23 pm

72 FI squareback. It's been running great, but in the past I would get the generator light coming on randomly then changing brightness with RPM's. I could stop the car, let it sit and then it would go away. Eventually the light stayed on, but would change with RPM's. I've just noticed that the Brake warning light is lit to, and also is changing brightness with RPM's. This link likely was happening the whole time but I just didn't notice.

I'm going to check the connections, voltage at battery at idle, voltage at generator at idle and generator and battery at 2500 RPM and I'll report back.

Any suggestions about why the brake warning light is tagging along? I'm not so hot with electric, so where, what else should I be checking?

Mon Sep 17, 2012 1:01 pm

Sounds like the generator brushes are worn. Replace them and clean the commutator.

Mon Sep 17, 2012 2:24 pm

I checked and cleaned all terminals on the regulator and the generator.
Voltage (key off) at battery = 14.43
Idle voltage at battery 14.43
Idle voltage at generator 2.52
2000 RPM voltage at battery 14.78
2000 RPM voltage at generator 6 and changing depending on RPM

Voltage at D+ when short DF to ground at 2000 RPM =~22

I pressed on the top brush when engine was running and light stayed on. I'll remove the generator and look at the condition of the lower brush and clean the commutator.

Mon Sep 17, 2012 4:33 pm

Ok, brushes are above their mounts. I can remove the generator strap and rotate the generator to see the lower brushes, BUT getting the belt off/back on will be a chore. I don't have the proper 24-24mm wrenches to get the pulley off. WTF were the engineers thinking that day. Why not just keep the same pulley knotch as the T1 so that I can get the darn belt off and out of the way.
By loosening the strap and moving the generator forward, I can likely get the belt off, but it is tight and I won't be able to get it back on. Is there a tool or a trick that I am missing that the T3 world has developed to get around this silly problem?
I can see that my commuter is pretty shiny and not filled with carbon. It may have been through a few rebuilds though, as there appears to be some wear on it's surface.
BUT
That shouldn't matter right? I'm charging fine, thus the output from my generator is ok and not source of my light issue. (right?) So where would/should I be looking next?

Mon Sep 17, 2012 5:00 pm

I took an emery board to the commuter and it is now a gleaming shiny piece of metal. I did notice that the generator light gets dimmer when I turn on the headlights, but still stays on.
Also, I disconnected the blue wire at the generator (Edit: should say regulator) and the light went off.

Mon Sep 17, 2012 6:33 pm

werker wrote: I took an emery board to the commuter and it is now a gleaming shiny piece of metal. I did notice that the generator light gets dimmer when I turn on the headlights, but still stays on.
Also, I disconnected the blue wire at the generator and the light went off.

There's your likely issue- blue wire is for the oil light, green is the field for the gen light.

Mon Sep 17, 2012 7:39 pm

Aarg. Got me on an important detail. I disconnected the blue wire at the REGULATOR and the generator warning light went off.

Mon Sep 17, 2012 7:53 pm

werker wrote: Aarg. Got me on an important detail. I disconnected the blue wire at the REGULATOR and the generator warning light went off.

Ah, OK. Yes, that will happen. Time to check continuity on all the wires, then replace the reg if that pans out.

Tue Sep 18, 2012 8:26 am

Just a double check, this means that I'm charging and regulating correctly and can drive as necessary. That is, I'm not going to run out of juice somewhere along a drive.... correct? I'm just dealing with a wiring issue on the other side of the light from the generator/regulator.

Tue Sep 18, 2012 8:53 am

werker wrote: Just a double check, this means that I'm charging and regulating correctly and can drive as necessary. That is, I'm not going to run out of juice somewhere along a drive.... correct? I'm just dealing with a wiring issue on the other side of the light from the generator/regulator.

Not necessarily. As Tram said, if it is not a wiring issue, such as a short to ground, or partially broken wire, etc, it could be the regulator giving signs of going bad or it is already.

Tue Sep 18, 2012 9:10 am

If you take off the generator strap you can tilt the generator up enough to pop off the belt.

Tue Sep 18, 2012 9:28 am

Mike Fisher wrote: If you take off the generator strap you can tilt the generator up enough to pop off the belt.

That's the thing. Not necessarily. It is very tight and will be difficult/impossible to get the belt back on, thus I'm not satisfied with this as a method. There needs to be a better way/tool to accomplish this task. I did use this method to rotate the generator around to see the bottom brushes however.

Quote: Not necessarily. As Tram said, if it is not a wiring issue, such as a short to ground, or partially broken wire, etc, it could be the regulator giving signs of going bad or it is already.
Darn, your right. I'll keep checking.

Tue Sep 18, 2012 10:41 am

ifyou drive your dub with no genny you will be fine for a small while but eventually get stuck on the side of the road witha dead battery and can cause damage to the battery...

here is a pdf I found that may help. generators

good luck

Wed Sep 19, 2012 9:38 am

Thanks for the link to the reading material. I'll download and read. You can never do to much research...
Well, just to keep it fun: remember how this began as an intermittent problem? Well after my futzing around the other day and never being able to get the warning light to turn off, I went inside and called it a night. Came out yesterday to make a small 2 mile run to a meeting and the light stayed off! I figured it was a temperature issue and the light would come back on later in the day when it heated up around here (Central Valley Ca), but it never did. So, this experiment yielded no results. I'll post again once the issue comes back and I'll start all over again.
Thanks for playing.

Thu Sep 20, 2012 12:31 am

werker wrote: Thanks for the link to the reading material. I'll download and read. You can never do to much research...
Well, just to keep it fun: remember how this began as an intermittent problem? Well after my futzing around the other day and never being able to get the warning light to turn off, I went inside and called it a night. Came out yesterday to make a small 2 mile run to a meeting and the light stayed off! I figured it was a temperature issue and the light would come back on later in the day when it heated up around here (Central Valley Ca), but it never did. So, this experiment yielded no results. I'll post again once the issue comes back and I'll start all over again.
Thanks for playing.

You did hook the blue wire back up to the regulator... right?

Did the light come on when you started the car and then go out and stay out?

Thu Sep 20, 2012 10:35 am

Oh yea, I hooked the wire back up. It does the correct oil-and-generator-light-at-startup-then-turn-off-at-running trick...
So this is a good thing... right? 8-[

Thu Sep 20, 2012 11:20 am

if the belt is TOO tight then you need to shim the pulley out a bit and fit it correctly

you should have a total of 10 shims

and the nut on the gen Should be a 21
thats what i have always used

Thu Sep 20, 2012 1:04 pm

werker wrote: Oh yea, I hooked the wire back up. It does the correct oil-and-generator-light-at-startup-then-turn-off-at-running trick...
So this is a good thing... right? 8-[

Yep- Now, did you do anything else like clean connectors or tighten down the regulator screws?

Fri Sep 21, 2012 10:36 am

Tram wrote: werker wrote: Oh yea, I hooked the wire back up. It does the correct oil-and-generator-light-at-startup-then-turn-off-at-running trick...
So this is a good thing... right? 8-[

Yep- Now, did you do anything else like clean connectors or tighten down the regulator screws?

Oh yea, both. The thing is though, when I did that the light didn't go out. At least not at first...

Fri Sep 21, 2012 12:45 pm

werker wrote: Tram wrote: werker wrote: Oh yea, I hooked the wire back up. It does the correct oil-and-generator-light-at-startup-then-turn-off-at-running trick...
So this is a good thing... right? 8-[

Yep- Now, did you do anything else like clean connectors or tighten down the regulator screws?

Oh yea, both. The thing is though, when I did that the light didn't go out. At least not at first...

Your likely issue was a bad ground at the regulator, and tightening the mounting screws fixed it. The regulator itself MUST have good contact with the body or it won't work.