All systems freaking out - RESOLVED

[th3_f15t]

Bit of a curious one this... Here's what's happening on my dashboard:

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When it goes into this state, I can't access most of the modules to scan for fault codes or live data. I have to leave the car off for over 30 minutes then when I clear everything it's fine for anywhere between 5 and 15 minutes before starting again. I did manage to get some persistent codes which I've pasted below:

U112100 Databus missing message - Passive/Sporadic
01312 Powertrain Data Bus - sporadic 014-Defective
01316 ABS Control Module - sporadic 013-Check DTC Memory
01299 Diagnostic Interface for Data Bus (J533) - sporadic 004-No Signal/Communication
00907 Intervention load Management
01309 Power Steering Control Module (J500) - sporadic 004-No Signal/Communication
00778 Steering Angle Sensor (G85) - sporadic 004-No Signal/Communication

I originally thought it was a faulty ABS sensor so one-by-one I went round and disconnected them to see if the problem went away (i.e. the faults were persistent and it didn't go into freak out mode). Then I tried taking off the DDC sensors on the dampers but again nothing stopped it reappearing.

I'm suspecting something has failed, but not sure where to investigate next. Anyone got any thoughts or pointers about how I can try and get to the bottom of this issue?

[pudding]

A quick bit of googling reveals U1121 is the Haldex controller, so could all be related to that.

Guessing this is a MK6 or MK7 R?

[th3_f15t]

Yeah, Mk6 Golf R but with an upgraded Haldex controller. The battery for the remote fob is dead, could that be the simple fix you think?

[pudding]

Sorry mate, not really clued up on MK6s but I would be surprised if a bad key caused all of that!   I think only the alarm bit uses the battery.  The immobilizer is passive - I think!

Is it a HPA controller?  Might be worth dropping them a line to see if they've seen those errors before?

[th3_f15t]

Interesting line from one of my old posts here:

http://www.mk5golfgti.co.uk/forum/index.php/topic,101525.msg1033237.html#msg1033237

"I broke one of the connectors"... Maybe I should check that and re-wire one..? Stay tuned.

[pudding]

Yeah it's worth checking the wiring.  It won't like a broken CAN wire in particular!

Nice car btw 

[doylebros]

If you've had the cluster out (previously in carrying out other mods) remove it and reconnect as I've had crazy faults from that area.

[GVK]

Thinking out loud - If you can access the back of the diagnostic connector and see where the twisted pairs go to (which 4 pins) you can check the resistance of the CAN with everything off.... and the CAN voltages with the car running, they usually add up to 5 volts but not perfect half values if that makes sense?

Say you have 1.5 volts on one can pin, the opposite pin will have the 3.5 to add up to 5 volts. You should never see 2.5v + 2.5v. Not sure on VW what exact resistance you will see but on the Ford stuff that I've worked on, I've seen 60 ohms on each pair. Anything wildly different points to a CAN error in the wiring or component.

I did a quick Google to see if I could find a mk6 diag connector pin out but nothing concrete to be found.

[th3_f15t]

Small update. I suspected that maybe the cluster was at fault as all the modules talk to it and everything started complaining about sporadic/no communication with cluster. Other issues I should point out are that the locks will unlock randomly and while the engine is running, the needles will stop working for a second then come back randomly.

Removed the cluster and put the ignition on to test for faults, the locks still started going off randomly and when I plugged the cluster back in, it wasn't 100% working right. The warning gong was sounding but there were no messages on the display and now when I try to start the car it acts as if it's in gear and says "Select P/N on selector!" at me, even though it is (the cluster does recognise what position I've selected correctly in the top right).

Also getting consistent faults from the steering control module and steering angle sensor. Also, as of today, started getting air bag warnings for "low voltage". Currently have the batter disconnected and on charge.

Basically, I don't know what the f*** is gonig on still. Any more thoughts? Haven't got a volt meter to hand at the moment so testing voltages is out for now.

[pudding]

I wonder if it's just a really weak battery?  That or bad ground somewhere perhaps?

[th3_f15t]

The battery is the original and I can barely make out the built in indicator of the acid state. I've put it on charge to see, leaving it a few hours to see if it continues to draw full charge (meaning it's knackered out) or whether it drops, thus meaning it's holding charge at least.

Funny this started after cold weather...

[th3_f15t]

Charged the battery, didn't belp. However...

While driving the car can be fine. When it does go, the DOC, parking sensors and other comfort functions fail. To test, I pulled the 15A fuse for the DOC while parked and the faults mostly stop. Replace the fuse and shortly after it goes mental again. As soon as I pulled the fuse it comes down.

Thinking that the comfort control module is faulty?

[th3_f15t]

A quick bit of googling reveals U1121 is the Haldex controller, so could all be related to that.

Guessing this is a MK6 or MK7 R?

Bang on the money it seems... I replaced the battery in my fob but noticed the controller still wasn't responding. Checked the connection to the remote-receiver box in the boot (cleaned out, WD-40 and re-seated) and now after a 40 mile commute to work, there are no more issues.

Going to keep an eye on things and if it plays up again I'll get the stock controller back into the car and ditch the HPA one but seems happy enough for now.

[imabigdipper]

Just popping in to say THANK YOU!  I had very similar issues, see my forum post here, after accidentally disconnecting the CANbus harness that goes to the cluster, above the pedals, while my battery was still plugged in. My CANbus was in a total panic, wouldnt communicate with the ECM, ABS, Airbags, Steering assist, etc. Cluster was doing the same exact things yours was. I thought, theres no way this is all caused by a haldex controller, but I gave it a shot.

I have a VDV Haldex controller, which sits inline to the factory haldex harness. I unplugged it, started the car, cleared codes, and voila, everything gone. No idea why a 3rd party haldex controller caused so many crazy CANbus communication errors, but I'm glad its fixed, i thought i had broken a module/harness somehow.