THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

Howdy folks,

As the title reads the charge light is lit on the dash. I've searched the forum, read the posts, and am still struggling. Here's what I've done so far, not necessarily in order.

Replaced a glazed and stretched fan belt.
Cleaned and completely disassembled the molex connector.
Replaced the wiring harness under the tin after damaging a connector.
Load tested the batteries, one was bad, replaced both.
Had ordered a spare regulator for just in case, swapped it, no change.
Cleaned ground connections.
Removed the alternator as I thought is was non functional. Rebuild guy said everything was good.

The voltage at the red wire on the alternator is 25.8, truck running obviously. Same reading at the molex and batteries. I also bought a din usb charger with a volt meter on it. This meter reads the same. The batteries are at 25 volts, truck turned off.

So the batteries are good, brand new. The belt is properly tensioned. The wiring must be good as the volts are the same between the alternator and the battery. I don't know what else to look at. Can anyone please advise for what to be checking? The manual says to read the amps between D+ and B+ if, motor stationary key on, charge light goes off when regulator is disconnected. But you don't read amps between different wires, so I'm confused.

I bought this truck a few months ago in California. It's been a fun project. Cylinder 4 had zero compression. Turned out the Piston had a hole in it. Fixed that. Swapped some rebuilt carbs on and proceeded to drive it from the bay area to Yosemite, Sequoia, through death valley and onward to Moab. It was a great trip while in between jobs.

Now I'm in a remote spot in South West Colorado, back to work. Funny enough my boss used to own a 710, he's a car guy all the way. There are also multiple tour companies around here that use pinzgauers on the gnarly pass roads, which are still covered in snow. Seeing them around town is a trip.

If I get this 712 running proper I'd like to start a build thread. As the truck sits now it has a camper box on it, which I've started to remodel and improve upon, beginning with solar and fixing the non existent departure angle which requires moving the camper door. Anyways...

Any suggestions will be greatly appreciated! Thanks.

From my past experiences you have tried everything I would have done. The only thought I have is to check the diode/resistor pack but any fault with that would more likely keep the indicator from lighting rather than leaving it on.
You might trace the light blue wire from the indicator light to the regulator just to make sure there isn't chaffing or fraying anywhere on it.

Good luck!

There are 4 terminals of interest. Bat (red), D+ (Blu), D- (Blk), and DF (Yel)

The D+ and Bat outputs should be almost identical Voltage when running, check
to see if they are. The charge indicator lamp connects to the regulator but
logically the lamp connects to Bat on one side and D+ on the other. So if
D+ is not outputting for some reason it looks like ground and the lamp is ON.
When D+ is close to Bat's output voltage then there is near zero volts across
the lamp so it's off. P.S. that's why the lamp can flicker at times or be dull
when the RPM is too low as the D+ output is below the Bat voltage.

The terminal DF is a control, it drives the field winding. When this is a low
voltage the winding is getting all of D+ voltage across it and the Alt is outputting
hard and furious. Measure DF as well and see what that voltage is. It should in the
ballpark of 8 to 12v under a lite load and far lower when the load is high e.g. high
beams on and anything else you got to load up, e.g. DF drops with increased load.

All the while above, Bat should be as you indicated a bit over 25V. If all that hangs
together you may just have a short to ground on that lamp

A representative Regulator -- Alternator schematic attached.

D+ is is 3-4 Volts. While alternator was about 25.6.

DF is 60-80.

The readings were bouncing all over. The meter was not displaying any consistent numbers..

Hmmm, that has to be the other way around. DF can’t get above D+. So has to be D+ is a high voltage. Soooo this implies
the regulator thinks D+ is not outputting thus the regulator is driving DF to low voltage to get more output. Bad
connection somewhere between the Alt and Reg terminal. Or a bad regulator but I think you replaced that already.
Most likely a open circuit somewhere.

Well I decided to retest based on your response rmel.

Red wire 25.4
Blue wire 1.6
Yellow wire 1.5
Yellow wire with all accessories on 1.4

Not sure why these results differ from the previous...

These numbers are quite far off from the baseline you described. I have poked around checking for resistance in the blue wire that grounds from the regulator. Zero ohms between the regulator and indicator lamp. Also no resistance between the alternator and regulator for the blue wire, D+.

As I pointed out before, Blue = D+ and is a copy of the RED e.g. Battery output.
It should track the primary output voltage very closely. At 1.6V it sure ain't.
Make sure D- and the alternator case has a real good chassis ground. Just for
yuks, start the truck, then while it's running Open the Battery ground break
switch -- does it still run even with that open. See element #53 in the Pinz
schematic, that relay should close with a running Pinz and normal D+ output and
the engine should continue to run. If it does D+ is present enough to pull a
24V solenoid which would suggest something wrong with the measurement.

Well I recleaned the alternator ground. Good to go in that realm. To be clear, I checked the ground strap that goes from the alternator to the intake manifold stud.

I started the truck and while running turned off the battery switch. As expected the truck turned off.

Rmel, you mentioned #53 as a relay in the wiring diagram. I'm seeing it as the tail lamp. Could you have meant #45, relay to battery main switch? I think that's what you meant as it's a solenoid connected to D+.

Thank you for your help so far, this issue has been driving me nuts.

I believe you each may have different schematics. On the Swiss schematic #53 is the relay for the battery main switch.

Do you perhaps have an Austrian Pinz?

You pretty much have confirmed that D+ is not outputting.
Given that there's also no current flowing through the Field
winding so there can't be any Battery output either. So your
Batteries have to be discharging -- no?

Can't eliminate the wiring, alternator or regulator as the problem
child at this point. But I am now wondering how your Alternator
guy confirmed you have a good alternator? Did he bench test it
under load or spin the pulley and say yep -- Ezzz good

I've been tempted to drive the truck for awhile and take readings at the battery before and after operation, just to see what happens.

The alternator guy has a good reputation. Not sure exactly what he did. He said the diodes tested good, the bearing is in good shape, and the alternator was not an issue. And that was a $90 service.

Ouch -- $90 for a health check. And I thought the Bay Area was outrageous

Well you could try one thing before dashing off to drain your Batteries. Disconnect
the Alternator output terminal and measure the output at the Alt. terminal. I'm
betting it's gonna be zippo. At that point at least you would know no D+ no B+.

This morning I disconnected the red wire from the alternator. Truck did not want to run, but when it did, 1.8 volts at B+. Hooked it back up and it ran like normal. Volts at 25.

Disconnecting the B+ was to isolate the output from the Battery to see
if there was any output -- which apparently there is none. If D+ has a
voltage on it e.g. ~24V which is supplied by the regulator, and DF is less
than D+ then the field winding on the Claw pole rotor would be energized
and you'd be cranking output.

So the only conclusion one can make under the above condition if you do
also see any D+ voltage is that the problem is likely in your wiring harness
or connections -- as you have already replaced the regulator -- I think. It's
probably that simple

Correction

The charging system on the Pinz is very similar to that of a Porch 911, obviously 24V not 12V.
Bosch Alternators and regulators for both.

Both are what is refereed to as a "B circuit" for the Field coil. What I described was a "A circuit".
I need to correct that.

The difference is; For a B circuit, one side of the Field winding is tied to D- e.g. Ground, the
other side connects to DF and is driven by the regulator to a positive voltage thus energizing
the field winding. Driven until D+ gets to the pre-set voltage of approximately +28V.

I described a A circuit; Where DF is driven toward ground by the regulator at the DF terminal,
the the other side of the field coil connected to D+. In both cases DF is driven until D+ reaches
the preset voltage of ~28V. Sorry about the confusion.

I also verified this by measuring an Pinz Alternator I just happened to on the bench from my 712.

Still doesn't fix your problem, but I wanted to get this correction out.