WA - mk4 4motion guru?

[beale187]

Hi - which motor needs to be removed? Do you mean the precharge pump?

Anyway I’ve run fault codes again - I’m getting 00526 - brake light switch (F) 27-10 implausible signal - intermittent. (Going back I see this was there when I bought the car and it didn’t seem to be binding then).

I also checked the measuring blocks and saw it is detecting both hand brake and foot brake switches. The pump is running 100% of the time when the engine is running but off when the engine is not running (ignition on).

Clearly this should not be so, but there don’t seem to be any other blocks on the Haldex that are meaningfully measurable.

Should I be checking something else? I know the ECU and ABS control units send signals, but should I be looking here and if so what for?

Or if the pump is always running does that mean the haldex controller is bust? No other options?

First thing you need to do is fix the brake light switch code. Link below for a new switch ($15 just do it)
Brake Light Switch - Euro Revolution

The Haldex gets it's signals from the ESP and ABS readings. A few things to check, however you'll need VCDS (VAG-Com) or similar for all.

Measuring Blocks in the ABS module. (ch.04)
Confirm these are all within tolerance. A dodgy YAW rate sensor (indicated by "Rotation Rate" in VCDS) can cause ABS/Haldex issues. This pic was taken when my YAW sensor was fried hence the reading whilst the vehicle was stationary was WAY out.

ABS module (ch.06)
check "Longititude Acceleration"

ABS/Wheel speed sensors (ch.01) - I don't think this is the case for you as no ABS light is coming up but can't hurt to confirm

When stationary make sure they all read "0"
Set up your laptop and phone camera facing the laptop screen. Go for a short drive and confirm readings match the odometer.

imo, if you've serviced the haldex and all of the above is good then my guess is your Haldex controller is fried. In which case you won't always get a DTC.

[Perthdisco]

Can concur my other car is a LR Discovery and a faulty brake light switch causes a full set of Xmas tree lights and cascading ABS ESC faults and shutdowns.


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[beale187]

I am no expert for sure only understand that the 2010 Tiguan that I have has the Gen 4 Haldex. This has a removable filter and motor.

Not sure the difference on earlier versions. Later versions don’t have the removable filter it seems.


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I was under the same impression only the later model haldex's required this process. Then you mentioned it, then I got googling and seen this.

Generation 1 Haldex Pump VW Audi 02D525557 TT R32 4Motion - Haldex Parts and ECU Repairs by Auto Fault Finder 01270 440151

[Perthdisco]

Great site and saw this regarding a clogged filter failure mode. This is Gen 4 but specific to the motor strainer filter blockage!

Note binding rear axle symptom at low speed and tight turns




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[Overtaker]

Thanks for the advice guys. I have ordered the brake switch, so that will be a small job for next week when it gets here. I've checked the ABS measuring blocks ch 1, 4 and 6. the speed lines up, and I think everything else is in spec (though the YAW rate was a bit high in one of the checks?). Here are the readings at 0, 30, 40, 50 and 60kph (While I have the latest VCDS, I'm not that clued up on what its telling me):

[Perthdisco]

Thanks for the advice guys. I have ordered the brake switch, so that will be a small job for next week when it gets here. I've checked the ABS measuring blocks ch 1, 4 and 6. the speed lines up, and I think everything else is in spec (though the YAW rate was a bit high in one of the checks?). Here are the readings at 0, 30, 40, 50 and 60kph (While I have the latest VCDS, I'm not that clued up on what its telling me):

What is the code reader device you use?


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[Overtaker]

VCDS v20.4 on my pc and a hex+can cable (HC440352 rev B) from Ross-Tech

[beale187]

VCDS v20.4 on my pc and a hex+can cable (HC440352 rev B) from Ross-Tech

All of those readings look within spec unfortunately and I'm fresh out of suggestions.

If a brake switch doesn't fix the problem then I can only conclude you need a new haldex controller

[Overtaker]

ok, so it wasn't the brake switch. I eventually sourced a haldex controller from a wrecker in QLD, and got Joe down at Elite Euro to see if he could find anything else it could be, which he couldn't. fitted the replacement controller, and all is now well..

[beale187]

Good to hear it's all sorted! Back to dubbin'