[GreenTreg2]

Hi all

I have 2011 UK 7P T3 with adaptive air suspension and 4XMOTION (low range, centre diff lock and rear diff lock).

Based on lack of info I can find on this subject, I suspect that 4XMOTION might not have been an option on 7P in US? I already gather that adaptive suspension was not available in US on 7P.

To briefly set the scene I recently purchased the car with 70000 miles. A number of minor niggles all sorted (or pending) but I have annoying Diff Lock errors in Module 34. Here are the errors on VCDS -

Address 32: Differential Locks        Labels: None
   Part No SW: 0BN 927 771     HW: 0BN 927 771
   Component: Quersperre          5220 
   Revision: H04         Serial number: 112108253604 
   Shop #: WSC 00000 000 00000
   VCID: 0109BF9E5896408E04-8054

3 Faults Found:
02062 - Differential Lock
            003 - Mechanical Failure - Intermittent
02412 - Differential Lock Rear
            003 - Mechanical Failure - Intermittent
16353 - Control Module - Internal Malfunction
            014 - Defective - Intermittent

The errors will clear. But they almost immediately return. I have already replaced the module with another secondhand module but the errors remain identical.
I tested all the 12 wires between J647 and the diff lock unit. All have continuity.
I tested the 3 wires from fuse box C to J647. All have continuity. All 3 fuses OK. SC3 and SC4 are permanent live. OK. SC43 is ignition controlled live OK.

I have removed the diff lock motor and the motor spins.
I did wonder how G407 worked. According to the wiring diagram G407 is within the diff lock motor, and is a Engine Temperature Sender. But how does it sense engine temperature from inside the diff lock motor? Simple - it doesn't.
Here it gets a bit strange - There are no wires on the diff lock motor side of the electrical plug for G8 Oil temperature sender. But there are wires for G407 Engine temperature sender which do go into the Diff Lock Motor. So it seems that oil temperature is being measured via terminals 5 and 6, rather than terminals 7 and 8. Could it be that my diff lock motor was wired up wrong ? Should the temp sender wires from the motor housing be going to terminals 7 and 8 ??? To clarify - there are no connections from the motor side of plug T10bh at positions 7 and 8. I now think this is all OK since this is the same as T2/7L

Resistance Testing -
Terminal block T10bh
Across Terminals 1 and 2 G460 Axle differential lock Hall sender 1 I get 2k ohms. In all postions.
Across Terminals 3 and 4 G461 Axle differential lock Hall sender 2 I get 2.6k ohnms. In all positions.
Across Terminals 5 and 6 G407 Engine temperature sender I get 1.05k ohms at garage temperature. I waved a heat gun at the motor block for about half a minuute and the resistance started to rise to about 1.08k ohms.
Across Terminals 7 and 8 vacant
Across Terminals 9 and 10 Switching for V304 motor (I assume) I get 23 ohms.

Terminal block T2ea
Across Terminals 1 and 2 I get 1.7 ohms. When I turn the motor by hand I get 2.3 ohms.

When I connect 5V across T2ea terminals 1 and 2 the motor spins without issue.
There is aluminium rot setting in on the edge of the circuit board inside the motor - the sealant on the PCB is beginning to peel by the cable entry and there is corrosion on the PCB.

My part number is Nidec 405.541 / 0BN341601 / 97062435000 (I have seen other units labelled with same VW and Nidec numbers with 97062435001)

I have 3 outstanding questions -
Do any of the readings above confirm that the motor is faulty?
Do the errors being reported match with anyone else's experience, and what was the outcome?
Does anyone know for sure if there is any difference or not between my diff lock motor and T2/7L motor - Nidec 405.553 / 0AB341601 and I think this is also same as 95562490401 Cayenne 955/ 9PA. I know that they are different numbers and surely VAG would not issue identical parts with different numbers?? Yeah right.

Any help or clarification gratefully received.
Thanks very much.

 

[Blownvette]

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[GreenTreg2]

Hi Blownvette. Not really intermittent. The errors show all the time, except immediately after Clear DTCs. So the errors will only disappear when I make them go away. As soon as I start driving they all come back again. I have not looked closely enough to establish in what order they reappear, but certainly very quickly. I did not notice any corrosion on any of the terminals, but always worth a clean. Thanks.

 

[Blownvette]

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[GreenTreg2]

Ah, right. Now I get you. Actually I don't know that there is an issue. Haven't taken it off road to try it yet, but wanted to make sure all was working before I did that.
I have seen a few examples on the net about some of these errors, but no-one with any solution, and in fact not much follow up at all. Perhaps I need to head off into the fields and see what happens?
Testing by jacking the car off the ground, engaging locks, and trying to move the wheels by hand in Neutral would only show up if the lock was not at all engaging, but not much more.

Would still be very interested to know if there is really any difference between 0AB341601 and 0BN341601. All the pictures I have seen of them show them to be identical externally, and the external plugs are wired identically (with pins 7 and 8 vacant) even though 7P wiring diagrams show that these pins are for Oil Temperature Sensor. Maybe they were going to be different during the design stage, but when it came to production they used the same motor but continued with the new number and forgot to update the wiring diagrams?

Thanks for your responses.