[jonandse]

Hey all, I just successfully repaired (not replaced) an original 0AD341601A transfer case motor.
The car is a 2004 Touareg V6 with 297000km on the clock, flashing with the diff lock switch and complaining about "System Fault Workshop".
VCDS revealed a 02039 g398 010 potentiometer open or short to +plus.
After reading up on the various problems folks have had with poor battery (typically code 008, not 010), broken cable wires (a variety of errors) and replacing the motor I first checked all the wires in the cable loom and they were found to be all good.

I dismounted the motor and found that it had some road salt ingress. I removed the locking washer for the potentiometer, disconnected the cables and turned the potentiometer by hand. It rattled. I washed it with isopropanol, IPA. Quiet.

There seem to be two potentiometers and one NTC resistor in the black potentiometer case. The three outer pins are potentiometers on each side and the middle two pins seem to be the NTC resistor connection. The potentiometer readings should be between 1.2k-2.2k when turning the wheel.
Mine had discontinuity for part of the revolution, not sure if this is the expected behaviour or not but anyway IT WORKS after putting it all together again. Error codes are gone, no more "System Fault Workshop" warning.

So before firing the parts cannon for a couple of hundred $$$, try cleaning your potentiometer with some IPA electronics cleaner first - especially if you have 02039 010 and not 02039 008.

Good luck!

 

[TommiT]

Very good first post!

 

[injuhneer]

I too have disassembled the transfer case selector motor. My vehicle had the binding/jumping behavior. I fully disassembled the motor. This is a simple servo-motor. It has a standard permanent magnet DC electric motor inside the case. That means brushes to provide power to the armature via a commutator with a permanent magnet field. The motor shaft drives a small reduction planetary gear train very much like that in PMGR (permanent magnet gear reduction) starters. The motor case is sealed which means all the nifty (conductive) dust from brush and commutator wear are trapped inside the motor case. This is where the problem was in the case of my vehicle. The resolver (electronics that measure the position of the output shaft) were OK on my vehicle.

After disassembly a solvent was used to clean the armature and its commutator then the magnets and case. To recondition the commutator the armature was put in a lathe and the commutator turned until smooth (just a few thousandths skim cut). Afterward the commutator pad gaps were back cut starting at the winding and moving AWAY from the windings. I have a small tool (made many years ago) that is essentially a bit of hacksaw blade with a hook ground into one end. It is quick and relieves the insulation between the pads easily on small motors.

A note here: Do not use sandpaper to resurface the commutator. This leaves small abrasive particles in the (soft copper) commutator pads that wear the brushes prematurely. If you do this with a drill motor for rotation use fine metal cutting file to gently file the commutator pads until smooth. Mind the connection points to the windings while doing this.

A check for winding shorts was done between the commutator pads to the shaft and to the rotor. All was well. There were a few areas of the windings that the coating looked thin so they were coated with some additional urethane conformal coating then left to dry.

The motor bearings were lubed, the planetary cleaned and lubed then the armature put in the case, the brush plate, planetary, and electronics assembled. A quick test with 12V showed the motor to run smooth and fast. A few bumps of power were applied to rotate it close to the position marked when it was disassembled.

From there it was a standard install. A quick drive around the neighborhood with a few hi/lo switches confirmed that it was working correctly. A couple of seconds and the hi/lo change completed. No more binding or jumping from the drive train.

I wonder how many of these motors were scrapped but could have been repaired easily through cleaning or simple refurbishment.

 

[New2Tregs]

The two repair write ups above are yet another example why this site is great and immeasurably important. Detailed info that helps resolve problems owners run into with their transfer cases.

 

[TommiT]

A very good post but what you have done is regrettably beyond the capability of the vast majority of so-called "technicians" who are now, it seems, just followers of what the computer says and fitters of new parts.

It's hard to find proper mechanics!

 

[New2Tregs]

It's hard to find proper mechanics!

Sad but true.

 

[injuhneer]

A very good post but what you have done is regrettably beyond the capability of the vast majority of so-called "technicians" who are now, it seems, just followers of what the computer says and fitters of new parts.

It's hard to find proper mechanics!

Part of the problem is time. We hobbyist-enthusiast types can take the time to effect a repair rather than swap a part. If a shop only allows 30 minutes (arbitrary number) to swap one of these motors once the diagnostic time is spent there just may not be enough time.

I on the other hand can take the time to do such repair work because:
1) I know how
2) I have the tools, etc
3) The T1 is not my only vehicle

I suspect many of the techs have the training but don't get to use it when the fast part swap option is the preferred method.

My son is currently working through the auto-tech program at our local college. I am watching the curriculum with interest. In his first semester they are covering electrical troubleshooting in one of the courses.