Generator light comes on when ignition is turned off

[NateBug1970]

Hello everyone! So I recently bought my 12 yr old daughter a 1970 beetle to fix up and have ready by the time she's able to drive. I had to replace the battery because my wife left the lights on. The new battery had the - & + on the opposite sides from the old battery and so without checking I began to hook up the new battery backwards and along came some sparks. This blew the stereo fuse and caused my generator light in the speedometer to come on and stay on after the ignition is turned off. The generator and oil lights both still come on and go off as normal when the engine turns on. Does the light staying on mean that the generator was blown? Thanks in advance for any answers.

[VW_Jimbo]

So…..

That is an Alternator. Not a generator. Newbie mistake.

The light remaining on means you reversed polarity at the regulator and killed the diode(s) within.

If you know how to rebuild an Alternator then you got this. If not, purchase a new or rebuilt unit and swap it out.

That picture makes it look like the thick red wire is coming out of the Collins hole on the fan cover! Really odd looking!

Is there a bluish colored wire connected to the alternator? I am unable to tell from the picture.

Good luck!

Heads up! You might want to remove that engine compartment photo ASAP, before the engine compartment police come for you!
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[NateBug1970]

Thanks for the reply. These are the three wires connected to the alternator. So I guess there's no external voltage regulator on these which explains why I couldn't locate one.

[ashman40]

Yeah, sounds like you blew the internal regulator in your alternator. The best option may be to go to your FLAPS and source a rebuilt alternator ('75-later Beetle) with a Lifetime warranty. Autozone is pretty good both in quality and supporting the warranty. Have the FLAPS test the alternator before you walk out of the store. Take your alternator pulley parts to assemble on your new alternator. You don't want to spend hours installing a dud only to have to remove it and reinstall a 2nd replacement alternator.

There should only be 2 wires connected to the alternator. The larger B+ wire connects to the threaded stud and smaller D+ wire to the D+ push on terminal.
I see a 3rd wire there which looks like it connects to the case as a ground wire. The earlier generator wiring had 3-wires, one of which was a brown ground wire. This wire is not used when wiring an internally regulated alternator. I recommend you disconnect it.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Starbucket]

Remove the 3 screws that hold the brush (where the blue wire connects) and see if you just melted the brush wire.

[ashman40]

[NateBug1970]

Ok so you are saying that I should disconnect and leave disconnected the extra write that is not connected to the D+ and B+ when I install the new alternator. Also, I am thinking of transitioning from the my current 1600 to a 1776 for more power and daily driving. Is there a certain type of alternator that I should get anticipating the engine change or will it not matter? Thanks again for the replies.

[ashman40]

[Starbucket]

[NateBug1970]

Awesome! Thanks guys

[ashman40]