No Communication to Engine Control Module

MillarC · Jan 2, 2019

Hi Guys,

I recently picked a 2005 t5 174 axe for what I was hoping was a bit of a steal and an upgrade from my T4. The previous owner had an intermittent starting issue, where after turning the key it would:

1. Not prime the fuel pump
2. Not glow the plugs
3. Show the ASR light
4. Start the radiator fans after a few seconds
5. Crank but not start

Turn the key off and on several times and it would prime the pump and start. It got to the point where he was turning the ignition on and off for 20 minutes to get it to start. He narrowed it down to a faulty ecu, put it in the too hard basket and parked it up.

I bought the van hoping that I’d just need to fit a replacement ecu. I bought an ecu from a wreck, made it into a clone of the original ecu, plugged it in and it didn’t change anything. I’m not convinced that the ecu is at fault and I’ve confirmed that the ecu I bought was from a running wreck. On a side note, there doesn’t seem to be any info on cloning ecus for the T5 on this site, thinking I should put a guide together (That's if it doesn't eventuate that me cloning the ecu caused the problems

)

Doing a scan with VCDS brings up a lot of no communication with Engine Control Module faults:

Code:

Tuesday,01,January,2019,20:12:14:45847
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 18.9.0.2 (x64)  HEX-V2 CB: 0.4437.4
Data version: 20180927 DS296.0
www.Ross-Tech.com


VIN: WV1ZZZ7HZ5H054XXX   License Plate: 
Mileage: 131270km-81567mi   Repair Order: 



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 7H (7HA - VW T5 2005)
Scan: 01 03 08 09 15 17 19 46
 
VIN: WV1ZZZ7HZ5H0XXXXX   Mileage: 131270km-81567miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: Redir Fail!
   Part No SW: 070 906 016 BD    HW: 028 101 183 5
   Component: R5 2,5L EDC         7001  
   Shop #: WSC 02756 785 00200
   VCID: 53F38188F7EE79EF737-5184

No Faults Found
  or DTCs not supported by controller
  or a communication error occurred

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 7H0-907-37x-ASR-F.lbl
   Part No: 7H0 907 379 G
   Component: ASR FRONT MK25      0103  
   Coding: 0007205
   Shop #: WSC 02756 785 00200
   VCID: 392FD3207542A3BF99B-513C

1 Fault Found:
01314 - Engine Control Module 
            004 - No Signal/Communication

-------------------------------------------------------------------------------
Address 08: Auto HVAC        Labels: Redir Fail!
   Part No: 7H0 820 045 R
   Component: CLIMA/AC            0202  
   Shop #: WSC 00000 000 00000
   VCID: 3431E21452205ED74AD-513C

1 Fault Found:
01299 - Diagnostic Interface for Data Bus (J533) 
            013 - Check DTC Memory

-------------------------------------------------------------------------------
Address 09: Cent. Elect.        Labels:. 7H0-937-049.lbl
   Part No: 7H0 937 049 K
   Component: BORDNETZ SGVER 1.0  1901  
   Coding: 0000101
   Shop #: WSC 02756 785 00200
   VCID: 3A2DCC2C7044A8A7901-513C

2 Faults Found:
01299 - Diagnostic Interface for Data Bus (J533) 
            013 - Check DTC Memory
01341 - Control Module in Instrument Panel On Comfort CAN (J285) 
            008 - Implausible Signal

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 6Q0-909-605-VW5.lbl
   Part No: 1C0 909 605 A
   Component: 3C AIRBAG VW51      0008  
   Coding: 13123
   Shop #: WSC 02756  
   VCID: 221D144CFDD4C067A81-513C

1 Fault Found:
00588 - Airbag Igniter; Driver Side (N95) 
            32-00 - Resistance Too High

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 7Hx-920-xxx-17.lbl
   Part No: 7H0 920 850 G
   Component: KOMBI+WEGFAHRSP VDO V03  
   Coding: 03702
   Shop #: WSC 00280  
   VCID: 2E05F07CB90C74073C9-513C
   WV1ZZZ7HZ5H054688     VWZ7Z0D1043099

1 Fault Found:
01314 - Engine Control Module 
            49-00 - No Communications

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.lbl
   Part No: 6N0 909 901 
   Component: Gateway K<->CAN    0001  
   Coding: 00006
   Shop #: WSC 02756  
   VCID: 70B92E0463B822F76E5-513C

1 Fault Found:
01314 - Engine Control Module 
            49-00 - No Communications

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 7H0-959-433.lbl
   Part No: 7H0 959 433 B
   Component: C2B Komfortgerát     0004  
   Coding: 00069
   Shop #: WSC 02756  
   VCID: 323DE40CAD3450E7581-4B1E

   Subsystem 1 - Part No: 7H2959802
   Component: Tõrsteuer.FS KLO 0203  

   Subsystem 2 - Part No: 7H2959801
   Component: Tõrsteuer.BF KLO 0203  

4 Faults Found:
01362 - Close Switch for Tailgate/Trunk (F124) 
            29-00 - Short to Ground
01331 - Door Control Module; Driver Side (J386) 
            53-10 - Supply Voltage Too Low - Intermittent
00932 - Electric Window Motor; Drivers Side (V147) 
            62-00 - No or Incorrect Adjustment
01332 - Door Control Module; Passenger Side (J387) 
            53-10 - Supply Voltage Too Low - Intermittent

End----------(Elapsed Time: 01:12, VBatt start/end: 12.1V/12.1V)-----------

I’ve only managed to get the ASR light to disappear once since getting it home and, on this occasion, I had a full connection to the ecu. Unfortunately, this was before I really knew what was going on with the van and didn’t take advantage of it. I Didn’t even record what codes were read from the ecu…

Now this is where I start to go down the rabbit hole, testing anything and everything that I can think of. In the end it's probably just going to be something simple.

The ecu is switching the 109 relay when the ignition it turned on but it doesn’t seem to be doing much more than that. The fuel pump and glow plug relays aren’t switching because the ecu isn’t switching the ground for those relay coils. I’ve checked the power to the ecu, albeit with the plug not connected to the ecu, and I get 12 where I should, and it seems to have a good ground. Thinking now that I should try and measure the voltage with it connected to the ecu.
Here’s the pinouts for the ecu, pin 18 is supplied with 12V when switching on the ignition. This triggers the ecu to switch pin 49 to ground, which closes relay 109 and powers up the ecu fully from pins 3, 5 and 6.

Neither of the ecus are dead, I can still connect to it with VCDS, I just can’t read any of the actual fault codes from it and my flash tool can read and write on both. I found that on the pre-facelift T5s VCDS works on the diagnostic wiring (K-line) rather than canbus. So I thought it must be a canbus fault.

I started looking at the canbus wiring and doing some testing with a multimeter. I got a resistance of 66 ohm between can-high and can-low - which is the resistance that I should be getting, based on what I’ve researched. This is measuring at the instrument cluster connector. Disconnecting the ecu and the resistance increases to 1 kohm or more. This tells be that the wiring between the instrument cluster and the ecu is ok. Measuring the voltage of can-high to ground and can-low to ground both measure about 2.5V. I was expecting a voltage differential of about 1V between can-high and can-low but I guess that’s only if there is data being transmitted. I’d need an oscilloscope to do any more testing here… Maybe there is a faulty module disrupting the network?

I also thought it may be an immobiliser fault. Just to check I dismantled the key and turned the ignition on with just the blade of the key. I got a flashing immobiliser light, which I wasn’t getting before, so this must be ok. I’m guessing that the instrument cluster must do some kind of initial check for the immobiliser, otherwise there would have to be communication to the ecu?

So, I’m here looking for suggestions on what I could try next because this has turned into a bit more of a saga than I was hoping! Currently I’m working on powering an ecu on the bench and attempting to read the faults via the K-line directly. If this works maybe I have a poor 12V supply or ground to the ecu that isn’t allowing it to boot up fully? I’m still curious why VCDS will connect to the ecu but not read any of the faults from it. After this I'm not quite sure what else to try before tearing the loom apart and throwing parts at it!

Sorry for the long winded first post, just thought that it would be easier if I could cover everything that I’ve looked at.

T5 TDI · Jan 2, 2019

I'm well out of date (about 20 years

) but you could try disconnecting the ABS controller just to eliminate that. It's always a good idea to disconnect controllers one at a time as a test unless they directly affect your fault (so no point in unplugging the ECU or the dash and hoping for a result!)

Speaking of the dash, the fact that your scan shows the diagnostic interface code in more than one place could point to the CAN gateway which is part of the dash on your van. Also ff you do have the dash out at any time have a good look at the loom behind it for damage.

The interface itself is unlikely to be the problem because on the old model the van doesn't use the (limited) CAN network for diagnostics. Good luck!

MillarC · Jan 3, 2019

Thanks for the suggestion! I think you may be right in saying that the CAN Gateway is causing the issue. I tested the ecu on the bench, connected it to my VCDS cable via the diagnostic pin on the ecu (K-line on pin 72) and I got the same result when scanning the ecu as I did when it was in the van. It connected and got the software number etc but it couldn't connect to read any faults. Looking around online it seems that it needs the gateway to read the faults.

Hopefully I can get an instrument cluster next week!

I looked at the wiring behind the dash and it all looks fine. I'm fairly confident that the wiring at the ecu is also fine. I don't want to mess it up too much. Yet....

toucanspeed · Jan 3, 2019

The instrument cluster also controls the immobiliser so when disconnected you get an immobiliser vault. I would check that all modules are seen by the gateway (on the instrument cluster) and then disconnect all those not needed to see if they are dragging down the can bus. You’ll need the ecu and instrument clusterobviouslyto start the van. My understanding is if the immobiliser is faulty the engine will start and then die straight away.

This is all based on a logical approach, so take with a some scepticism but happy to bat ideas with you.

MillarC · Jan 4, 2019

Interesting, I found this in the instrument cluster yesterday. It is connecting to the abs module and airbag module but it didn't seem to have anything from the steering angle sender. Do these transporters have the steering angle sender? I'd guess that it would only need that for stability control which I'm not sure that my van has. I've only disconnected the abs controller so far because it's easy to get to

T5 TDI said:
Don't forget you will need to match the immobilizer to the key again if you change the dash, but it looks you already have Vag-Tacho or similar so no problems there for you extracting the 4 digit (SKC) code.

It it quite a usual thing with certain faults for VCDS to be able to 'see' a controller fine but not not be able to communicate with it if it won't play ball even if it is not actually on the CAN network at all like the Cent Conv controller isn't on our older vans.

Thanks, I've found software to get my SKC code, which seems to work on the current cluster. I've bought a cheap cluster to test so hopefully it is here next week. No big deal if that's not the issue but I think it's worth trying before going for more expensive options.

T5 TDI · Jan 3, 2019

Don't forget you will need to match the immobilizer to the key again if you change the dash, but it looks you already have Vag-Tacho or similar so no problems there for you extracting the 4 digit (SKC) code.

It it quite a usual thing with certain faults for VCDS to be able to 'see' a controller fine but not not be able to communicate with it if it won't play ball even if it is not actually on the CAN network at all like the Cent Conv controller isn't on our older vans.

T5 TDI · Jan 4, 2019

With ESP = Steering angle sensor. With ASR = No steering angle sensor.

MillarC · Jan 8, 2019

My second hand instrument cluster arrived today but it seems that it was an issue with the ecu. The flash must have been corrupt on the original ecu and copying that across to the clone gave me the same fault. I found a flash online, flashed the ecu and away it went! Never has a fuel pump priming sounded so sweet!

Thanks for your help guys. Now I just need to decide whether to keep the t4 or the t5...

No Communication to Engine Control Module

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