Hit a speed bump and van shut down and came to a stop. Scan shows numerous module communication errors.

Bigsidavies

Bigsidavies

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A slight repost of the thread I started in the engine topic, but hoping for a new audience with electrical know-how.

I hit an aggressive speed hump at about 20mph and all doors unlocked, abs/traction control warning light came on and tpm light came on. Van ran about another 200 metres then just died, apparently from fuel starvation.

Doors won’t lock/unlock and dis shows both sliding doors open even though they are not.

Van wont start as there appears to be no communication between various control modules.
My guess is that something has tripped or blown or become disconnected in some way.
I’ve checked every fuse, both in the dash and under the battery and there’s nothing obvious.
I’ve a feeling that there’s loss of power maybe to the bcm or ecu.
Attached is a VCDS scan showing all the communication errors.

Does anyone have any ideas what to check before I call out an auto electrician.
 

Attachments

  • Log-VW51ALY-WV1ZZZ7HZHH112736-208630km-129636mi.txt
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that log shows:

short to ground,
short to pos,
loads of low battery codes

have you cleared the codes and rescaned?

did you bottom out the van on the speedhump? - damaged the loom for the adblue tank? - or that lower tank its self?

battery voltage?

main fuses under battery?

engine fuses behind headlight?

add a charger to the van and check voltage?
 
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I think there’s 3 scans all gone in that log together.
The first one has all the low battery stuff because we flattened the battery trying to start and having indicators on for 8 hours etc. That one is dated Tuesday.
I charged the battery yesterday and put it back on, cleared the codes and rescanned.
The later scans taken today in that log just show the control module problems.

No, I definitely didn’t bottom out. It’s just a new speed hump with a mental angle of attack, was like an impact and all the doors unlocked.
 
any chance of a fresh scan with the good battery?
 
It’s in that log mate. Scroll down. For some reason it’s put three scans in one log.
 

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  • Log-VW51ALY-112393.txt
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No, he’s about 45 miles away, but he’s thinking it’s a canbus break or short and as I’d been having errors relating to short to ground with various adblue sensors I’m going to be investigating the wiring from the ad blue plug working back up the loom.
 
Idea is if there's some can bus wires Ben caught that would short the network out and prevent the van from starting.

Looking at some drawing now
 
J583 - Control unit for NOx sender
J849 - Control Unit for sensor electronics
J 881 - Control unit for NOx sender 2

All have can bus wire to them that link back to the ECU which has the canbus terminator resistor in a short on these could blind the network as it can't see end of line and cause the van not to start.

They all share a common earth too that's linked in the wiring harness and they all share the same power line fed off a 15A fuse in fuse box B Number 28

In relation to
32111 - Voltage Supply for Particulate Sensor
P24D0 00 [035] - Short to GND

The particulate sensor (G784) is controlled by control unit J849 referenced above the 3 control units run from each control unit (near the adblue tank iirc) and up to a 17 pin red connector located under the passenger seat

31130 - Reductant Level Sensor
P203D 00 [035] - Short to Plus

This also shares the T14g black 14 pin connector near/under the AdBlue tank as the common ground for the Box and particulate sensors and the signal and linbus wires for the AdBlue heater and power wire for it fed from fuse box C number 43 30A fuse also the feedback leg of the tank level sensor for the AdBlue is in this connector and the power to it plus as stack of other stuff like the adblue pump.

I'd start by taking the under panel off and inspecting the wiring near the adblue tank @Bigsidavies
 
Chris you’re a star. Thanks for the effort. Looks like it’s axle stands and waterproofs in the morning mate.
I’ll let you know how I get on.
 
Well, I’ve had the undertray off and closely examined all the wiring to the ad blue tank and everything in the vicinity and it all looks good. No wear marks anywhere, no obvious broken cables and all pins in multi plugs look nice and shiny.
All errors still remain.
Next step I think is to go back to the fuses in box B, especially 9,20,32,34
 
battery disconnect and reset . . disconnect all your camper power and get that out the way for now,

then a rescan to see what modules are talking,

all we need to start with is the gateway, bcm and ecm. - to get the engine running



www.t6forum.com

[Guide] Full Van ECU Reset (Capacitive Discharge) -- How I Done It --

Full Van ECU Reset (Capacitive Discharge) -- How I Done It -- The T6 is full of ECU`s, Modules, CAN Buses and Data packets . . . . . Just like your Phone or PC right. The motor vehicle industry has spent years with research and development making the modern car/van Data and electrical system...
www.t6forum.com www.t6forum.com



.

side doors etc are all from the BCM.
 
I’ve done the capacitive discharge when I had the battery off. Although I didn’t disconnect my LB. Would that make a difference?
I’ll disconnect the LB tomorrow, do the ecu reset and see what happens. But my feeling is that I’ve lost power (some or all) to the BCM or similar.
 
you could post a pic of your SA fuse box to compare?
 
just a thought. . .

have you got any rear lights?

or rear parking sensors?

there is a LOOM junction under the passenger double seat? ( i think yours is under the carpet now? ) - maybe thats popped appart from the speed bump?


1702043184213.png
 
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