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Fri Feb 24, 2017 10:39 am

I have read some great threads on this topic:
http://www.thesamba.com/vw/forum/viewtopic.php?t=672761&highlight=battery+light
http://www.ratwell.com/technical/Alternator.html http://ratwell.com/technical/ChargingSystem.html

But I would like to validate what I think I need...which is a new Regulator.

I stole the follow test from busdaddy from this thread; http://www.thesamba.com/vw/forum/viewtopic.php?t=672761&highlight=battery+light

1) This is what I am seeing when the Key On / Engine Off

2) I used a long wire. One end with a spade to connect to a body ground.

3) The other end, I used a wire to poke into the GREEN wire at the regulator.

4) This is the result.

Opened up my regulator. But It doesn't appear to be the old school type...Solid State?

Is this test confirming I need a new regulator?

Thanks

Fri Feb 24, 2017 10:49 am

Well the regulator is probably toast now! What is this bus? Is this a type 1 with a aftermarket Alternator? That 76 right! Yeah, the thing you did I would not try. But it did prove the alternator light is good and that it's something else. That green wire shows here as being on the armature. So I would say the Armature circuit is likely open. Could be a brush worn out.

Fri Feb 24, 2017 10:57 am

Sorry, I did forget the golden rule of letting others know what we are talking about. It's a 1976 VW bus (type 2) with the type 4 motor. Stock wiring.

Fri Feb 24, 2017 10:59 am

Can't speak about weather or not the alternator is aftermarket or not. But her are some pics from when I rebuilt the motor.

Fri Feb 24, 2017 11:05 am

Don't blame the reg yet, it could still be fine. You should have disconnected the plug and grounded the blue wire, but regardless you've proven the light works and the wiring to the front is OK, now check both ends of the red wire for continuity.

Fri Feb 24, 2017 12:47 pm

busdaddy wrote: Don't blame the reg yet, it could still be fine. You should have disconnected the plug and grounded the blue wire, but regardless you've proven the light works and the wiring to the front is OK, now check both ends of the red wire for continuity.

Oops! I guess I miss understood that procedure. I hope I didn't ruin it!

I will check continuity from the regulator plug D+ (red wire) to the Alternator D+ (red wire). Making sure both are unplugged.

Thanks

Fri Feb 24, 2017 2:05 pm

busdaddy wrote: Don't blame the reg yet, it could still be fine. You should have disconnected the plug and grounded the blue wire, but regardless you've proven the light works and the wiring to the front is OK, now check both ends of the red wire for continuity.

OK, well I had to practically pull the alternator to conduct this test. But I tested all three wires (Red, Brown, and green) from Regulator plug to alternator plug. All continuity checks are very good. I also checked the large red cable from the alternator to the battery, it also checks good.

I guess it's time to take my alternator in and have it checked?

Fri Feb 24, 2017 2:20 pm

I guess if my alternator wasn't putting out correct voltage/amps, then my light would come on. Which would lead me to believe the regulator is bad. Am I wrong? Any other checks?

Fri Feb 24, 2017 3:20 pm

DeltaBravo wrote: I guess if my alternator wasn't putting out correct voltage/amps, then my light would come on. Which would lead me to believe the regulator is bad. Am I wrong? Any other checks?

busdaddy^^^

Fri Feb 24, 2017 5:08 pm

Quote: 3) The other end, I used a wire to poke into the GREEN wire at the regulator.

Opened up my regulator. But It doesn't appear to be the old school type...Solid State?

Is this test confirming I need a new regulator?
Probably not. Your test is interesting in that it confirmed that the regulator is passing current to the alternator rotor (as it should). As long as the engine wasn't running, you probably did no harm. [If it was running - 'nother story.]

The current at the green wire was supposed to pass through the alternator rotor, then through the brown wire to ground (lighting the light in the process). The rotor is fairly low resistance (a few ohms), so it should have been equal to the wire in lighting the light. The fact that it doesn't points to bad alternator brushes, a bad rotor, or broken connection(s) in the green or brown wires.

Note: the regulator body MUST be grounded for the unit to work (the pin the brown wire is connected to goes to the regulator case)!

And yeah, that regulator defines 'solid state': nothing moves. :lol:

[Another nice thing: that regulator is completely repairable!]

Fri Feb 24, 2017 5:55 pm

telfordor,

You mentioned the regulator body needs to be properly grounded, I believe that might be the problem. :idea:

I will investigate that. Hopefully that's it!

And (lucky) I performed that test with key on/engine off :)

Sat Feb 25, 2017 11:46 am

I tested and verified good ground from the Regulator case to chassis.

Installed new (auto parts) regulator, still no light with ignition on/engine off.

Any other thoughts?

I still haven't pulled my alternator to have tested. Should I? What is the next step?

Thanks again.

Sat Feb 25, 2017 2:46 pm

Grab your ohmmeter. Disconnect the regulator. Measure the resistance between the green and brown wires. If you don't get a low resistance reading, then you have an alternator issue (rotor, brushes, harness, or connections to the front of the alternator).

Sat Feb 25, 2017 2:58 pm

telford dorr wrote: Grab your ohmmeter. Disconnect the regulator. Measure the resistance between the green and brown wires. If you don't get a low resistance reading, then you have an alternator issue (rotor, brushes, harness, or connections to the front of the alternator).

Just measured,

Is 2.43 M Ohms (2,430,000 ohms) to much?

Sat Feb 25, 2017 6:46 pm

Wayyyyyy too much. Bad alternator!

Sat Feb 25, 2017 7:22 pm

telford dorr wrote: Wayyyyyy too much. Bad alternator!

DANGIT! I'd much rather it be the regulator. Easier and cheaper :lol:

Sat Feb 25, 2017 9:38 pm

Could just be brushes...

Sun Feb 26, 2017 3:16 pm

telford dorr wrote: Could just be brushes...

True. I have time...more time than money anyways. :wink: I've never rebuilt an alternator, but I am sure I can figure it out. Using some common knowledge and http://ratwell.com/technical/Alternator.html#rebuild , I'm sure I will be ok.

With about $10 in parts, I can replace the bearings, slip ring, and brushes. And I will learn something in the mean time.

Luckly, this is a project vehicle and not my daily driver....not yet anyways. :lol:

Mon Feb 27, 2017 10:50 am

Well, I tore the Alternator down. Didn't "see" much that would suggest why it wasn't working. I took some pics. I did note the front bearing was slightly wobbly, didn't feel bad, but the front shaft (armature assembly) wasn't very solid. Rear bearing seemed in better condition.

Brushes; one was significantly more worn than the other. My theory is one spring is suppling more pressure than the other. I don't see any other reason they would wear so differently.

As far as any of the other parts (diodes, winding, exc...) how would I test them?

1-Rear bearing (from Korea)

2-Front bearing (from China)

3

4

5

I can get new bearings, brushes, and slip ring for just over $10 shipped. But I am worried none of this will fix the no charging issue.

And lastly, If my Alternator wasn't charging (I verified with a multimeter while the engine was running) why wouldn't my light in the dash illuminate? This is still confusing me. I feel there is something else I am missing.
Thanks

Mon Feb 27, 2017 4:31 pm

The dash light only lights when current can flow through the regulator, then through the brushes to the alternator rotor. Once the alternator starts outputting power normally, voltage from the alternator 'diode trio' (the three little diodes) overrides everything, forcing the voltage across the GEN indicator to (near) zero. Thus, the light goes out.

Grab your ohmmeter and measure the resistance between the two slip rings:

It should be a low value.

Also measure from either ring to the rotor shaft. Should be infinite.

If either test fail - bad rotor (e.g. bad alternator).

Otherwise, polish up those slip rings, reassemble, and remeasure the resistance between the green and brown wires, and see if it has changed any.

If the rotor measured OK but the other test fails still, I'd try a new brush holder assembly.