Voltage Regulator Question ( Please Help)
 

Car 911t 1973.5 2.4
Alternator Marchal

So a few weeks ago my battery died on me. I figured that the alternator was not charging. I had the alternator checked and turns out that it's fine. So I verified that the ground on the transmission was securely attached. Checked the cables on the selenoid starter. Also repainted my fan housing and made sure that all the grounds were clear of painted and tested the ground. The RED Alternator light is constantly on.

BTW Had the battery tested it was good...

I went out to my local parts store and they sold me a bosch VR. Installed it. Nothing... Red light solid

So I called pelican and was surprised to find out that I apparently had the wrong voltage regulator to begin with. Unfortunately pelican does not have these regulators anymore. Luckily i got my hands on one and it is being shipped.


My question is can it be something else than a regulator. I heard a loud clicking behind the dash when it first died and i would figure that when i put the bosch unit even if it's not the right regulator it would at least do something.http://forums.pelicanparts.com/uploa...1284731328.jpg

bump

Hello,

Have you checked the voltage at the battery when the car is running? It should be near 14 volts if everything is working right. Also, I once had a rebuilt alternator that tested fine on a bench, but turned out to be defective. I probably wasn't real helpful, but I wish you luck, and hope some of the more knowledgeable guys can help out.

once in a while i find that the alternator was changed to a internal regulator style in the past, and the old regulator was still plugged in.

If your alternator was replaced in the last 5-10 years, it could (probably) has an internal VR - part of the alternator.

They stopped using the external VR in 81 or so. The old one was on the L (driver's) side of the engine compartment by the relays.

Mine is still there on my 78, but it's disconnected. I have a newer alternator.

You might check to see if you even need the external regulator. Or if you have an internal regulator that is bad.

Ok I checked with John at Pelican ... I have an early style Marchal alternator which definitely requires and external Voltage regulator. Also voltage test on the battery... once the battery is charged the voltage does not change at any rev...

Seems like the VR is the issue but why did it not do anything when I put the bosch unit?

should I be looking at relays fuses etc...

the red charging light in your dash gauge needs to work with the ignition switch in the ON position. does it? 12V goes through it and grounds through the D+/61 terminal on the alternator. the blue wire. dead bulb=no charging. worn brushes can also interrupt that circuit if they don't touch the commutator.

Hey John,

Sorry iI blew my Tester and needed to go buy another before i responded.
Red light is on .... I tested the red wirer to the ground and got 12 volts BUT that is only because my battery is charged.
so are we still thinking its the regulator?

get an adjustable vr
 

i had the same problem,, the fixed vr's sometimes charge too low. The guy i have do myb alternators, told me to try an adjustable one.
i set it to 14v, all is fine now, that was in the spring.

Per Tech article "Alternator System Troubleshooting" under 914 on this site.
unplug the three wires on voltage regulator (if individual wires, note where
they were plugged in. Jumper wires D+/61 (blue) and DF (black) together.
Start car and measure voltage at battery. If voltage is near 14v, alternator
is good, voltage regulator is most likely bad. If voltage is still 12v, alternator
is most likely bad and voltage regulator condition is unknown at this time.
This is assuming all of your wiring is correct.

Glen Pettigrew

Edit: Do not let the engine run very long in the jumpered condition.
It will over charge you battery!

Ok so i jumped the cables as described above...Nothin... no change in voltage what so ever. Went back to the shop that the alternator was tested and they said that the alternator is good.

Something you should know. This is a 912 that was converted to a 911t. the wiring may not be spec.

- Red wire from B+ going to a live wire from the battery

- Brown wire coming from the alternator D- to a grown on the frame. there was a connecting wire going to the VR.

- black wire going from the DF on the Alternator to the DF on the old VR

- Another black wire going from D+ to the VR- this wirer is connected to a blue wire that activates the red light on the dash.

SO before i even start trying to connect the VR i should be getting something from the alternator. I'm at a total loss... Please help:(

http://forums.pelicanparts.com/uploa...1285119447.jpg

on with the key in the ON position and goes out when the engine starts?

sorry John if you mean the red light goes off.... No it does not

going back to m original problem..."I heard a loud clicking behind the dash when it first died "

Can this have anything to do with it?

So you jumpered the two wires highlighted in Red below?
And still only had 12v at the battery with the engine running at
or above 2000 rpm?

Correct

Small illustration to make sure i'm wired correctly....http://forums.pelicanparts.com/uploa...1285128173.jpg

wiring seems ok
 

see this drawing for the wiring. yours looks ok... I posted above that you may need an adjustable voltage regulator as the stock one does not charge high enough so you batter goes dead.

If your alternator is ok it is your wiring or voltage regulator.

wire it up as shown on the attached (you can find the legend on this site) item 3 and 4 are the alternator and voltage regulator..
http://forums.pelicanparts.com/uploa...1285129179.jpg

Ok;
1. With D- grounded to frame ground.
2. B+ connectect to battery.
3. D+/61 connected to DF via jumper.
4. Negative of Battery connected to frame ground.
5. engine running at or above 2000rpm.
6. still 12v only at battery.
= Alternator is BAD!
This test has isolated everything between the
alternator and the car, other than battery, frame ground
and Large Red wire between alternator and battery

Glen Pettigrew

OK I spend 3 hours with a Frank from Volta ( company that repairs rebuilds alternators)

Here is the problem. The Voltage regulator needs to be "jolted"as frank put it? in order for it to start working... what this means is that some alternators have a feature that upon start up a surge in power actually wakes up the VR into starting. The Voltage regulator can sometimes have this feature also but the one i purchased doesn't have it Frank also suspected that i may have difficulty finding one that does.

SO what we did is put the alternator on a testing machine and connected the VR. what we found was that the alternator was working well and that the VR was not working. He then put a positive connection on the VR's connection FLD. BAM it worked like a charm. So we then connected a wire with a resistor that is used in other alternators for that same purpose directly between the positive. There was leakage approximately 74 amps, meaning it would drain my battery after several days.

So this is the part where you guy's may not agree with the solution and even i am hesitant but i have no choice since this is the second regulator and I'm out of options. I will interrupt the connection and turn it on for one second after initial start up. Below is a diagram of what it looks like. the new wiring is indicated as green. Appreciate your comments or better ideas!