We've had this Golf 5 towed in last week, history unknown.
It starts & dies as per immobiliser fault.
There is no engine management light & No glow plug light when the ignition is switched on.
If the ignition is left on the cooling fans run up to full speed within 30 seconds & stay active until the ignition is off.
Carried out a full systems code read using VCDS, Autologic & Bosch KTS.
None of the scanners could access the CAN Gateway & all of them failed to access any ECU other than the Engine.
8 x faults logged in engine - a few related to missing ECU comms, no U codes - as below. present.--------------------------------------------------------------------------------
ENGINE ELECTRONICS
8 Fault(s) Present
18043 (P1635) POWERTRAIN DATABUS (No Message From A/C Control Module)
18058 (P1650) DRIVETRAIN DATABUS (NO MESSAGE FROM INSTRUMENT CLUSTER)
16955 (P0571) BRAKE LIGHT SWITCH F (IMPLAUSIBLE SIGNAL)
17978 (P1570) ENGINE CONTROL MODULE DISABLED
17056 (P0672) PREHEATING SPARK PLUG 2 Q11 (Electrical Fault)
17057 (P0673) PREHEATING SPARK PLUG 3 Q12 (Electrical Fault)
19558 (P3102) INTAKE MANIFOLD FLAP MOTOR V157 (NO SIGNAL)
19557 (P3101) INTAKE MANIFOLD FLAP MOTOR V157 (OPEN CIRCUIT / SHORT TO GROUND)
--------------------------------------------------------------------------------

It seems an odd fault for a Golf?
The engine ECU is communicating on KWP2000, not on the CAN lines - The CAN Gateway is inaccessible from any of the scanners when trying to communicate directly & not part of an Autoscan.
Any ideas chaps?

Hi
Just behind the o/s under dash relay plate, is the gateway interface, similar size to a packet of cigarettes.
The multi block connector & opening is at top,have had a few exact same symptoms as yours where gateway interface is full of water due to leak from badly fitted windscreens.
Will need coding in as the ones I had from TPS default to left hand drive settings.

Thanks for the reply Ian,
The Gateway on this one is up above the clutch pedal - as high as you can go, with a red plug on it.
The unit sits horizontally with the plug facing the driver.
I have removed it, I assume it's the gateway as it says GATEWAY on it!
Part No. 1K0907530F
I have had a look inside at the circuit board & terminal connectors & there is no sign of water ingress.

Jon

Hi Jonathan
Missed the fact you had an Autologic on it the first time round, Hasn`t Lawrence or Damon come up with an ideas ??
As immobiliser is in the dash unless the dash can talk to engine ecu via can it wont run.
I would next scope up the can lines & see what you have. If the wrong scope pattern is found start disconnecting any control unit on the line to see if any changes.

Thanks Ian,
Rang Damon at 5PM, first thing he did was tell me something I didn't know, which was going into MVB's 125/6/7/8 to display which ECU's the engine was able to communicate with.

I've sent him a scope pattern of the CAN signals to peruse, he's calling me back tomorrow - Top fellow!

Jon.

Hi Jonathan I had one very similar, we also have Autologic and Lawrence was doing his best but without any results. These do also have a problem with water ingress up the wiring loom to the ECU, they are always worth checking, our one had a rare electronic thermostat (Automatic) which leaked internally and pumped water up the loom into the ECU. Talking to our local VW tech he also said they are capable of pumping water up from the Lamda sensor all the way up to the ECU as well, they as a Dealer have seen a few of these.

I know yours is diesel but it is worth a look. I wish I had after 2 days of head scratching. Fortunately our one the water stopped at the multi plug and did not enter the ECU so after cleaning all green terminals the car ran perfectly.
John Kennard.

John,
did you have no comm's with any other system or just the engine??
Did you scope the CAN signals, I scoped mine & it looks very disturbed indeed!

Thanks for the info regarding the water tracking up the loom, that takes me back to the MK 2 Golf, coolant level sender pumping Anti Freeze into the fuse box.

Jon

I got a couple of hours on this today, I hooked the scope up to the Diagnostic Socket pins 6 & 14 & started pulling ECU multiplugs off to see if I could get a CAN capture that looked normal - anyhow the car is now in pieces with every ECU I could find unplugged -

Steering Rack, Engine, ABS/ESP, Column Module, Airbag, Wiper Motor, Air Con, Parrot, Radio, Dash etc......
I'm up to the middle of the car now & still..........

no difference on the scope

Tried a CAN Gateway - the pattern looked more normal, but still had parrallel parabolics sloping down between messages, but I still couldn't get comm's with the Gateway itself or any other system apart from engine (the other systems aren't surprising as the Gateway needs coding in).

My thoughts on this was that because the Gateway wasn't in the loop due to not being coded - it was sat watching data packages going by without getting involved in the data stream - Is that likely??

Now it's largely in bits, my next step is to scope individual ECU's on the convenience / infotainment & powertrain buses (the dash is unplugged) & see what kind of activity is present on the individual buses.
I'm also going to go with looking at power supplies / earths.

Any pointers at my procedures would be appreciated - Cheers,

Jon.

Hi Again
Are you sure the gateway its self is ok.
Have you checked the wiring to the gateway & maybe wired it in direct from the DLC.

This ones still ongoing Ian,
So far I have found a 12V supply to pins 1&2 of the Gateway Controller, which disappears when probed with a Teslite - I traced this back to the engine bay fuse box.
Fuse 12 was powdery when removed, I've stripped the fusebox which shows signs of moisture ingress.
A clean up with wire wool & Wurths excellent contact cleaner & power was restored.

I then had a steady voltage supply, but the scope pattern off the DLC 6&14 was still a mess, still no comm's.

A new Gateway ECU has been fitted & comms are restored with 95% of systems, the scope pattern is looking healthy but I'm still getting comm's issues with the Airbag & Central Electronics.

Ongoing............

Jon.