Haldex fault - control module incorrectly coded

I'm very interested to see the log files before any work is done - if there is something out of the ordinary.
Having the controller checked is certainly a way rule out things. Any specific reason to replace the pump? Certainly it's not an expensive one and will eventually wear out.
 
mmi said:
I'm very interested to see the log files before any work is done - if there is something out of the ordinary.
Having the controller checked is certainly a way rule out things. Any specific reason to replace the pump? Certainly it's not an expensive one and will eventually wear out.
Click to expand...
The van has done 147k miles on the original pump. No record of haldex ever being serviced when I bought the van at 95k so I got an oil service done at about 100k. It's now overdue an oil service. Service kit is £50, genuine pump is another £200. If I'm going to crawl around underneath to do the oil change and remove the pump anyway then I might as well put a new pump on.
 
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Out of interest, does the 4WD actually work in practice?
I would also have a good look at the wiring while crawling around underneath, and probably telling you to suck eggs, but make sure you clean out the hadex unit and filter screen when changing the oil. VW do not normally do this as part of the oil change, so is likely very clogged up.
 
manfrotto said:
Out of interest, does the 4WD actually work in practice?
I would also have a good look at the wiring while crawling around underneath, and probably telling you to suck eggs, but make sure you clean out the hadex unit and filter screen when changing the oil. VW do not normally do this as part of the oil change, so is likely very clogged up.
Click to expand...
I'm pretty sure the system works. I've just had a test on a gravel car park and after a fraction of a second of front wheel spin you feel the rear bog down and push the van forwards. I did the VCDS output test on the haldex clutch yesterday and it worked- I could hear the haldex doing something and no errors came up.

However, I did try to turn off my traction control using the dash button and it didn't work. Nothing happened with using the button. Can't say I've ever pressed that button in 5 years so there's no real bench mark that it's ever worked.

I'm discovered a while ago that VW liiterally just change the oil, and don't remove the pump and clean the gauze or wipe out the haldex unit. That's another reason for considering putting a new pump in.
 
Bigsidavies said:
I'm pretty sure the system works. I've just had a test on a gravel car park and after a fraction of a second of front wheel spin you feel the rear bog down and push the van forwards. I did the VCDS output test on the haldex clutch yesterday and it worked- I could hear the haldex doing something and no errors came up.

However, I did try to turn off my traction control using the dash button and it didn't work. Nothing happened with using the button. Can't say I've ever pressed that button in 5 years so there's no real bench mark that it's ever worked.

I'm discovered a while ago that VW liiterally just change the oil, and don't remove the pump and clean the gauze or wipe out the haldex unit. That's another reason for considering putting a new pump in.
Click to expand...
Clean out the HALDEX and gauze you may not need another HADEX they get sluggish when dirty eventually stop working. Mine had no recommendations for service at all @mmi suggested that I see to it and true enough even at a low mileage it was, according to the Independent VAG mechanic of my choice was absolutely "filthy and black" After removing the black cleaning the gauze or cant remember if changed it was restored. The other thing that affect 4 wheel drive and a whole host of other things are the wheel speed sensors. They are an absolute pain and must be poorly designed or could be better protected from the elements. I have had about at least 4 removed and changed and its a fair bet another one will go before long. I have not decided the best service interval for doing the HALDEX but is is far lower mileage than what is now suggested.
 
The service schedule for the haldex is 40k and as you say it would appear that it should really be less.
I might just do the oil service as you say and see what happens.
 
Further to my earlier post about the traction control not working. I have just tried the method with the hazards on and 5 presses of the accelerator and it did indeed work and turn off the TC. So it does appear to be functional.
I’ll try the car park wheel spin test again over the next few days in Scotland.
I’ll try a new TC button for the dash.
 
@mmi hopefully these 3 csv files include the data that you requested.
oddly some of the things you requested in mod 17 - instruments didn't exist on my measuring value list. Mostly IDE 00609 an 00610. I only had one option for each.
 

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Bigsidavies said:
@mmi hopefully these 3 csv files include the data that you requested.
oddly some of the things you requested in mod 17 - instruments didn't exist on my measuring value list. Mostly IDE 00609 an 00610. I only had one option for each.
Click to expand...
Excellent, thank you.
References to diff-lock in both 03-ABS and 17-Instruments are as expected - not coded, not available, etc.
Even the last line status "Open" is as it is in very similar van as yours - so nothing to report from ABS.
1754330313106.png

1754330692960.png
Note: in vehicle with diff-lock the status would be "not active"


More exciting data in the 22-AWD itself - for comparison the same value from a very similar van

1754330996108.png

It seems there is a circuitry measuring voltage but for some reason sensor 1 sensing circuit is shorted to ground? The 4.9 Volts probably indicates open circuits and thus the reference voltage 4.9 Volts is seen when no diff-lock present.

For reference below values from a van with diff-lock (lock open)​
1754331624041.png​
​
I would start by checking the connector at the Haldex for water ingress or corrosion. Pins 5 and 6 are for communication with diff-lock vacuum switch - obviously unoccupied now.

Oh, what does VCDS report for
IDE00019 Voltage terminal 30
Should be the normal 12+ Volts
 
mmi said:
Excellent, thank you.
References to diff-lock in both 03-ABS and 17-Instruments are as expected - not coded, not available, etc.
Even the last line status "Open" is as it is in very similar van as yours - so nothing to report from ABS.
View attachment 298288

View attachment 298291
Note: in vehicle with diff-lock the status would be "not active"


More exciting data in the 22-AWD itself - for comparison the same value from a very similar van

View attachment 298293

It seems there is a circuitry measuring voltage but for some reason sensor 1 is shorted to ground? The 4.9 Volts probably indicates open circuits and thus the reference voltage 4.9 Volts is seen.

For reference below values from a van with diff-lock (lock open)​
​
I would start by checking the connector at the Haldex for water ingress or corrosion. Pins 5 and 6 are for communication with diff-lock vacuum switch - obviously unoccupied now.

Oh, what does VCDS report for
IDE00019 Voltage terminal 30
Should be the normal 12+ Volts
Click to expand...
Thanks for your detective skills mate. I'm off to Scotland first thing so it will be Saturday now before I get a chance to crawl underneath.
I was leaning towards electrical/wiring. If you saw my post about 12 months ago it started with a flickering warning light that would go off for weeks/ months then come back flickering until it became permanent.
I'll check the plug and wiring as my first job.
The website mentioned above also says to open the control unit to check for corrosion/water ingress.
I'll have a look at those procedures and post the results on here at weekend.
 
Today I've had a crawl around underneath. Removed the Haldex control module and checked for water ingress - all looks fine. Checked the plug to the controller abnd the wiring to the plug and all seemed fine. Bone dry no signs of any water ingress.
Didn't check any actual wiring voltages as I don't have a meter.
Forgot to do the terminal 30 voltage.
Anyway, all reassembled and the same fault codes remain.
I'm thinking of doing a pump and fluid change this week as a matter of standard maintenance. I doubt that will fix the error codes, but it needs doing anyway.
 
Bigsidavies

Post in thread 'What Have You Done To Your Van Today?'

I've fixed the 4mo warning light that I've had on the dash for about a year. I've previously done loads of data for mmi and we thought we'd narrowed it down to a wiring issue.
I've had the haldex controller off, cleaned all connections and even pulled the unit apart to check for water ingress.
Anyway, today whilst at the park as there was only me there I decided to check the haldex function (even though it passed the test in VCDS) by dropping the clutch at 2500rpm on the loose gravel car park. Small amount of front wheelspin followed by a big rear wheelspin and two big lines in the gravel...
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