Need Help Fast! Alternator/Brake Light On & Low Voltage

Post by **Sluggo** » Sat Dec 29, 2007 3:34 pm

A few days ago my alternator light & brake light started coming on when I'd first start up but went away after a minute.

Yesterday morning when I started her up she wouldn't stay running. Seemed like no fuel getting to the carbs and the lights were on again. In addition, the volt meter only read 12v (normal is 14v). After several attempts she held an idle. Then when it warmed up the lights went out and the volt meter read 14v. Went fine all day until I got a block from home and the lights came on again and the meter read 12v again.

This morning I had the same problem again. This time the lights came on a few miles later and the volt meter went back down to 12v. Still made it where I was going. When I went to leave a few hours later I made it one block and the engine shut off (lights on and 12v). Tried starting her up again and it seemed like I wasn't getting any fuel. Went back and screwed around with the wiring and she started up again (lights on and at 12v from now on). Made it another block and she shut down once more. Same thing. Started her up a few minutes later and made it about 1/2 a mile before it stalled. Waited, started again and made it home.

Once home I checked all the wiring to see if I could find any breaks or shorts. Nothing. Changed out the Voltage Regulator and no changes. Made sure all my wiring between the battery, starter, voltage regulator, fuel pump and ignition were good. I did notice a grinding sound coming from the alt while running.

What do ya think? Time for a new alternator?

Post by **Sluggo** » Sat Dec 29, 2007 7:35 pm

The mystery grows.....

Figured out that my fuel pump & heater booster fan are going on and off randomly (when the ignition is on). Both have relays switched by the infamous "Blue Wire" to the voltage regulator. This explains why the bus runs and then feels like it's getting no fuel. Have it wired to the coil as a very temporary fix. Running the pump directly off the Blue Wire does not work.

Since the blue wire is also what controls the brake and alternator idiot lights, I'm assuming this must be it. I just replaced the entire blue wire (idiot lights to VR) several months ago.

It's dark now. I'll be spending tomorrow down there. Hopefully I'll get this figured out so I can re-install my calipers with the correct piston orientation and install the brake pad backing plates. Then I can install my new Compufire which is replacing the 3 defective Hot Sparks and the Pertronix with 4 different magnet positions.

hambone · Post by **hambone** » Sat Dec 29, 2007 8:24 pm

Could your regulator be goin' bad too? Seems like classic symptoms.

Post by **Sluggo** » Sat Dec 29, 2007 8:56 pm

hambone wrote:Could your regulator be goin' bad too? Seems like classic symptoms.

I changed it out already. Same problem. Also, I just realized that I ran the NEW Blue Wire through the nose on the right side. Right where it's crushed in at. I bet the blue wire (which is actually red now except in the engine compartment) got pinched and is shorting. I'll check it out tomorrow.

spiffy · Post by **spiffy** » Mon Dec 31, 2007 10:32 am

When my alternator went I was reading below 12 volts.

Post by **Sluggo** » Mon Dec 31, 2007 6:17 pm

It's not the blue wire. I ran a jumper and still had the same problem. Replaced the fuse and checked it's wiring. I just finished pulling the alternator. The wiring on it checks out too. I'll be putting in my spare "of unknown working status" alternator in a few minutes.

It actually looks to be in better shape than my current one. Except for the harness which I'll be switching out.

Wish me luck!

bus71 · Post by **bus71** » Mon Dec 31, 2007 7:12 pm

I had similar problems with our '74 bug. It turned out to be the brake light warning circuit. I pulled its plug, all o.k. Never fixed it because I know what bad brakes are. Good luck!

bus71 · Post by **bus71** » Mon Dec 31, 2007 7:20 pm

P.S. Don't disable this circuit if you are not in the know about brakes.

Post by **Sluggo** » Mon Dec 31, 2007 9:58 pm

bus71 wrote:I had similar problems with our '74 bug. It turned out to be the brake light warning circuit. I pulled its plug, all o.k. Never fixed it because I know what bad brakes are. Good luck!

I'll try that tomorrow. I know what bad brakes feel like.

New alternator, new regulator, rebuilt the harness, new "Blue Wire" all the way to dashboard. Same F$&KING Problem!!!!

Here's one that will keep me from sleeping tonight. When I have the blue wire plugged directly into the voltage regulator (just like stock) with no splitter for the fan or fuel pump relays, the idiot lights don't work at all. But when I use a splitter and connect the fuel pump, the idiot lights work. Did this 5 times. It just started happening. Makes no sense whatsoever.

Post by **Sluggo** » Wed Jan 02, 2008 3:00 pm

Figured it out. The first thing I tried was replacing the voltage regulator. When that didn't work I replaced the alternator. Then I still had the same problem plus that wacky deal with the idiot lights not working unless the fuel pump was plugged in.

Well, the alternator was the original problem. Which was solved when replaced. But the old VR was good and the new spare was bad. I put the old VR back in with the new alternator and now all is well.

Adventurewagen · Post by **Adventurewagen** » Wed Jan 02, 2008 3:05 pm

Nice work. That sounded like a pain in the butt. Sometimes its' just so hard to figure intermittant problems like that out.

Hippie · Post by **Hippie** » Wed Jan 02, 2008 9:58 pm

Oh and that new, bad part. That will mess your mind everytime.
Way to stick to it. =D>

Rob

Post by **Amskeptic** » Fri Jan 04, 2008 11:09 am

Get rid of or repair bad parts ASAP. It is extremely easy and likely that you will confound yourself if you are ADDING variables from a stash of parts where you don't quite remember why you pulled them in the first place. We want to narrow down the variables.
Colin

Post by **Sluggo** » Fri Jan 04, 2008 6:05 pm

Amskeptic wrote:Get rid of or repair bad parts ASAP. It is extremely easy and likely that you will confound yourself if you are ADDING variables from a stash of parts where you don't quite remember why you pulled them in the first place. We want to narrow down the variables.
Colin

*Noted*

Problem is that I didn't pull most of it. I just acquired them from various sources in unknown states of repair. The Voltage Regulator and Alternator both came out of my '73 Automatic that hadn't been run since 1994. They both looked to have been replaced just before the engine blew. The alt was bright & shiny (unlike the rest of the filthy, oil soaked engine & tin). Same with the VR. I just bought a brand new spare VR just in case. $30 at Autobone.

I plan on going through all my parts and having them tested at some point.

Itinerant Air-Cooled

Itinerant Air-Cooled

Need Help Fast! Alternator/Brake Light On & Low Voltage

Need Help Fast! Alternator/Brake Light On & Low Voltage