TheSamba.com :: View topic

Sat Dec 15, 2012 6:34 pm

Finally it is driveable! And it drives nice! Plenty of pep. I took it around the block and then for a 4 mile loop. Tonight I took the lovely Ms. Ruby to dinner with it.
Coming home, the generator light started to glow. I was thinking the headlights was causing it, but when we parked in the driveway with the lights out, the generator light was out at idle, but when I revved it the light began to glow. It got brighter with rpm. What up with that?

Sat Dec 15, 2012 6:58 pm

You have a generator/regulator/wiring problem.

First figure out for sure if you have a gen or alt.

If you have a generator, check that the brushes are not shorter than the cages they sit in.

Break open the "Idiot's Manual" by John Muir and read up on the "Red Light On" section.

Sun Dec 16, 2012 3:54 am

Thanks Eric. I have that book, but I hardly use it as it is too idiot for me. I have to plow past the systems explinations to get to the meat.
A few days ago, the connector for the gen bulb was shorted against something (wiper frame?) and wouldn't go out.
This car suffers from 44 years of who re-wired what!
The generator is rebuilt with less than a couple of hours on it, but I will inspect the brushes.

Sun Dec 16, 2012 7:14 am

Haven't had that happen to me, but I understand that the light will come on if there's an undercharge or overcharge. Sounds like your voltage regulator is shot, and it's allowing an overcharge situation. Get a volt meter and see what the voltage at the battery is. I suspect the volts go up too high over the norm (14v) as the rpm's increase.

Sun Dec 16, 2012 11:44 am

jlex wrote: Haven't had that happen to me, but I understand that the light will come on if there's an undercharge or overcharge. Sounds like your voltage regulator is shot, and it's allowing an overcharge situation. Get a volt meter and see what the voltage at the battery is. I suspect the volts go up too high over the norm (14v) as the rpm's increase.

Yes, as I rev it the system goes to 14.78VDC. The regulator was new and probably has less than two hours on it.

Sun Dec 16, 2012 9:00 pm

I don't know what the upper limit on the light is before it goes on due to overcharging. 14.78 doesn't seem outrageously high, but I don't know how sensitive the warning light is to an overcharge. Maybe someone else could chime in but you're probably on the right track. Luckily, VR's aren't that expensive.

Mon Dec 17, 2012 1:07 am

rbrandes wrote: Yes, as I rev it the system goes to 14.78VDC. The regulator was new and probably has less than two hours on it.
You should take voltage measurements at the two terminals of the Gen lamp. The blue wire coming from the VR and the black wire at the very bottom of the speedo should both have very nearly the same voltage. 1v difference is not unusual.

It could be that the electrical connections are dirty on one side or the other. If the voltage on the black wire is lower than 12.0v you could probably increase that by taking some sandpaper or a wire brush to the terminals and connectors between the battery and the Gen light. That includes connections to the ignition switch and the fuse box.

Mon Dec 17, 2012 10:00 am

Picked up a Made in USA regulator this AM at CarQuest. All is well.
Thanks for the help on this. I will keep the suggestions on file.

Mon Dec 17, 2012 10:15 am

that just happened to me...same issue...i posted from the weekend...It is almost like something is grounding out in the VR at the higher RPMs...so weird

Mon Dec 17, 2012 3:53 pm

rbrandes wrote: Picked up a Made in USA regulator this AM at CarQuest. All is well.
Thanks for the help on this. I will keep the suggestions on file.

Good. Would like to know what the voltage is on high rpm's with the new VR...? Pretty close to 14?

Mon Dec 17, 2012 4:10 pm

jlex wrote: rbrandes wrote: Picked up a Made in USA regulator this AM at CarQuest. All is well.
Thanks for the help on this. I will keep the suggestions on file.

Good. Would like to know what the voltage is on high rpm's with the new VR...? Pretty close to 14?

Well, now I suspect my digital VOM. It was showing over 15 volts with the new VR. So I got out the old Lafette and that showed 14 volts on the nose. It is rainy here and my wipers stopped working (need blades too!) so I haven't had it out.

Thu Dec 20, 2012 9:33 pm

I've got a '73 Super Beetle with a generator and the gen light is on at idle, if I hit the gas it goes away, but comes back at higher revs (around 3,000 RPM). I've replaced the battery and adjusted the timing. Engine sounds good but gen light on. Any advice would be greatly appreciated. Thanks

Thu Dec 20, 2012 9:55 pm

Did you check gen brush length??

Thu Dec 20, 2012 10:44 pm

New generator, but I will check the brush length and post back. Thanks.

Thu Dec 20, 2012 11:17 pm

Fan/gen belt too loose?

Do not want it too tight or ruin gen bearings.

Too loose and you will have the present problem.

Can also be caused by not getting the woodruff key locked in between the gen shaft and the pulley.....

Sun Dec 23, 2012 7:33 am

just a thought but i had that happen to me and it turned out the parking brake lever wasn't sitting all the way down and when i would get up some rev or speed it would jiggle up a little and cause my light to come on and glow brighter with the revs. i make sure the lever is all the way down and it has been fine. i also have an external meter that reads just fine when this does that. hope that helps!

Mon Dec 24, 2012 5:11 am

Did a full tune up yesterday and replaced the fan belt, light's still on but goes off with higher revs. Will look into it more later in the week. Thanks.

Mon Dec 24, 2012 6:01 am

Get the volt meter out & let us know what it's reading at higher rpm's...

Mon Dec 24, 2012 7:17 am

At work right now but will do in the next couple days. Thanks.

Mon Dec 24, 2012 8:19 am

How is the gen brush lengths?

How does the commutator that brushes ride against look like? If dirty or rough that could be a cause. A fingernail cardboard sander carefully used with engine idling can polish it up quickly.