Just another alternator /VR question....

[speedo]

71 2.2 just restored. New battery. Have to periodically charge. Alternator light is bright at idle, less bright at RPM but still glows. Yesterday the car was a bit hard to start, and light at lower RPMs was brighter. Ran a couple errands and noted light remained on when key was removed from ignition. Car barely started. Had to make one more stop and light stayed lit, but when time came for restart...nothing. Push started easily and made it home. Have not tested the battery for voltage under idle and load, will do that today. ..after I finish recharging the battery. That will tell me if the external VR is toast right? What does the indicator light staying lit with key off tell me...bad diodes?

Speedo

[wwest]

There is a relay inside the factory external VR that closes, connecting battery voltage to the VR regulator "relay" when the ignition switch is on. Relay contacts are sticking. Low charge rate may also relate to VR.

Put in a new solid state external VR, inexpensive fix/try.

[speedo]

Thanks for responding. Would the sticking relay inside the VR cause the dash light to stay illuminated even when the ignition is not on? I was always of the impression that a failed VR caused over charging of the battery, not under charging. As far as picking up a new VR...any recommendations?
My existing VR is a Motorola...probably not OEM. I just went to the garage to take the battery off charge, and noticed that the VR was warm to the touch. Also noted that my alternator light on gauge was lit? Car is off, no key in ignition, what would cause that?

Speedo

[timmy2]

simply put, the sticking contacts are providing a path for current to flow through the alternator to ground and that is why the light is on.
Our host sells remote VR's.

Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI

[speedo]

I looked at the wiring for the VR and there are two wires (red- D+ and black-DF) and a ground D-. My VR doesn't have the black-DF connected. It didn't come loose, it was never connected. In fact I can't see the loose wire anywhere.
Hmmm...

Speedo

[304065]

Indicator light staying on with key off = shorted diode = rebuild alternator

[speedo]

Any comments on the fact that I am not connected to the VR with the black DF wire?
Possible for me to have run with just the hot and ground?
Love doing these alternators...time to pull out my powerful skinny alien fingers that articulate backwards....

Speedo

[mysocal911]

Originally Posted by 304065

Indicator light staying on with key off = shorted diode = rebuild alternator

That's correct. And bad regulators don't cause the light to stay 'on' with the key 'off'.

[wwest]

Originally Posted by mysocal911

That's correct. And bad regulators don't cause the light to stay 'on' with the key 'off'.

With the external VR the alternator CANNOT be at fault in a way that results in the charge light remaining on.. VR relay stuck closed most likely.....

Unplug the VR, the light will go out.

[speedo]

I am going to swap out the VR and see what happens. Would still like to get a handle on where to pick up the black DF wire

Speedo

[wwest]

Originally Posted by speedo

Any comments on the fact that I am not connected to the VR with the black DF wire?
Possible for me to have run with just the hot and ground?
Love doing these alternators...time to pull out my powerful skinny alien fingers that articulate backwards....

Speedo

Either the alternator never worked or somewhere in time a new alternator w/internal VR was installed.

[304065]

Originally Posted by wwest

With the external VR the alternator CANNOT be at fault in a way that results in the charge light remaining on.. VR relay stuck closed most likely.....

Unplug the VR, the light will go out.

Sorry but you are wrong. A simple google search will turn up dozens of hits validating that when the alternator lamp is lit with the key removed from the ignition, that is due to a failed alternator diode.

In the normal case, the VR gets power from the ignition switch through the warning light bulb, which with the D+/61 trio (a single diode in some Motorola alternators used by Porsche) putting out less than the set-point voltage, gets sent to DF, the field, energizing the field. The energized field induces a current in the stator which is rectified by the main diodes and the trio - some current flows to B+ and some (from the trio) flows to D+/61, which voltage balances the battery voltage on other side of the warning light and the light goes out.

When a diode has shorted, the reverse is happening-- voltage from the battery is flowing across the shorted diode, into D+/61, into the blue wire and through the warning light and back through the ignition switch to ground. The regulator can be perfectly fine and this will still happen.

There is an old chart in Panorama an Up-Fixen Der Porsche that explains how the charging light works, I wonder if anyone has posted it here.

[speedo]

Originally Posted by 304065

Sorry but you are wrong. A simple google search will turn up dozens of hits validating that when the alternator lamp is lit with the key removed from the ignition, that is due to a failed alternator diode.

In the normal case, the VR gets power from the ignition switch through the warning light bulb, which with the D+/61 trio (a single diode in some Motorola alternators used by Porsche) putting out less than the set-point voltage, gets sent to DF, the field, energizing the field. The energized field induces a current in the stator which is rectified by the main diodes and the trio - some current flows to B+ and some (from the trio) flows to D+/61, which voltage balances the battery voltage on other side of the warning light and the light goes out.

When a diode has shorted, the reverse is happening-- voltage from the battery is flowing across the shorted diode, into D+/61, into the blue wire and through the warning light and back through the ignition switch to ground. The regulator can be perfectly fine and this will still happen.

There is an old chart in Panorama an Up-Fixen Der Porsche that explains how the charging light works, I wonder if anyone has posted it here.

So I took out the VR and replaced it...light stayed on. Then I replaced it with another...and the light stayed on. Then I replaced it with a third...and the light stayed on. Chances are that I don't have four failed VRs. Time to swap out the alternator.

Speedo

[speedo]

Newly built alternator from the local shop. Now I remember. Took my old one in and got this as a swap. Should be just a tidge more than 12 months warranty on this guy, right? How could I have killed it?

Speedo

[Targalid]

I am still confused about your wiring. You should have a three slot plug connecting to the three blades of the voltage regulator, next to the CDI box on the driver side of the engine compartment. The three wires are brown, blue and black. You don't have a three prong connector? Is the black wire not in the connector? My three prong connector has a tricycle shaped connector. The front wheel of the tricycle(narrow front of the connector) is brown, with the left rear wheel being blue and the right wheel black. Does this help?

[speedo]

I got the wiring figured out. No three prong connector, just three separated spades.
The various VRs I have have different connectors. At the end of the day it is blue (or red) to DF+, black to DF and brown to DF-.
Thanks for helping.

Speedo

[speedo]

Local shop tested it and it works and charges fine...great. Looks to be a remanufactured brand (Valeo). The shop says it has no issues. Now I am completely confused. So my VRs and alternator work, but battery is not being recharged and the alt light on dash stays on...hmmm. Open to suggestions.

Speedo

[mysocal911]

Using the alt. light as a diagnostic tool:

1. no light with ignition "on" not running
a. bad regulator
b. bad light
c. open slip rings
d. bad brushes

2. light stays "on" with key "off" - shorted diode/diodes

3. light glows brightly while running
a. open diode/diodes
b. shorted rotor/stator winding
c. shorted alt. light wire to ground
d. bad regulator

4. light glows dimly & gets brighter with higher RPMs - voltage drop,
e.g. @ alt. B+ post or @ starter connection

5. light flashes at low RPMs - bad slip rings

6. light glows dimly at all RPMs - open diode/diodes

[304065]

Lars, I think you have the connections mixed up.

Black= Dynamo Field = DF
Blue= D+/61 the famous blue wire, this connects to the bulb holder in the dash. Other side of the bulb holder is switched +12v
Brown- D- ground

[304065]

Also, is the remanufactured Valeo equipped with an internal voltage regulator? I would expect that it is. In this case you can ditch the external VR by unplugging it and taping off any bare wires. I don't recommend internal VRs for the cars that don't come with them, (82-) by the way- too much heat down there, and heat is the enemy of electrical components.