battery short and vcds scans

[Owain]

Hi,

I think I have built some shit whilst re-routing my trailer wiring. When I installed I took short cut and routed through van on inside; but am meant to be having rails fitted for bed; and silly me put wires where rails are to go.

Thought all was routed ok; but then had flat battery. Realised I had a 2A drain on main starter battery even with IGN off.

I have removed fuses to isolate my battery-battery charger from Main Battery and also removed fuses supplying trailer controller; also unplugged trailer controller.
I am now searching for shorts; pulled lines.

I have VCDS scan before I pulled fuses. Shows lots of battery voltage type warnings; in fact I took the scan after pulling fuses/unit.

I then cleared DTC's; went for drive and did new scan. Apparently most of faults gone; but how come it reports....

Chassis Type: 7E0
Scan: 01 03 04 08 09 10 13 15 17 19 25 5F 61 69


01-Engine -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
10-Park/Steer Assist -- Status: Malfunction 0010
13-Auto Dist. Reg -- Status: OK 0000
15-Airbags -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
25-Immobilizer -- Status: OK 0000
5F-Information Electr. -- Status: OK 0000
61-Battery Regul. -- Status: OK 0000
69-Trailer -- Status: Cannot be reached 1100
-------------------------------------------------------------------------------
Address 01: Engine
Cannot be reached

-------------------------------------------------------------------------------
Address 03: ABS Brakes
Cannot be reached

-------------------------------------------------------------------------------
Address 08: Auto HVAC
Cannot be reached


I don't understand; how can it say for instance Engine OK; then Address cannot be reached. Is Engine OK or not?I
Is HVAC ok or not. I am new to VCDS so not familar with how it reports stuff. Trailer not reached fair enough; unplugged.

Am just about to do resistance/voltage test on CAN J519/ T73B pins 20 and 21. This CAN goes to a lot of units includng Trailer controller and is only connection left connected to my trailer harness. Probably cut that CAN connection and then retest.

Why do I see those status OK's, but cannot be reached?

I am attaching my two vcds logs; maybe someone has some ideas.

All the best,
Owain

 

[Owain]

With IGN off

Diagnostic port 68 Ohm between CAN high and low. So as expected.

I snipped other CAN going to trailer controller in trailer harness where it enters harness. Again with IGN off; I get open circuit between CAN High and Low; no 60 Ohm. I also see 5.5V on orange/brown CAN Low, millivolts on CAN High. Not looking good.

With IGN on I see around 4v on CAN Low and 1v on CAN High.

I think I have really buggered something. Not suprising everything on that bus isn't talking.

Is there anything else I can check? Fuses? Pulling at straws....

 

[mmi]

I don't understand; how can it say for instance Engine OK; then Address cannot be reached. Is Engine OK or not?I
Is HVAC ok or not. I am new to VCDS so not familar with how it reports stuff.

The listing is a kind of "last known" status of the modules. Anyways, not reached is definitely not a good thing. The 19-Gateway, 09-BCM, and 61-Battery Monitor all are in within same box. The OBD connector connects directly into that - so that explains the communication between VCDS and those three.

I think there is only one line (pair) in the OBD connector and as it's communicating fine with 19, 09, 61 - then that line is ok. So the problem is on the "other" side of the gateway.

 

[mmi]

There are three buses down
- Convenience: HVAC, Infotainment, Trailer, etc
- Powertrain: engine, ABS, steering angle, airbag, etc
- Dash panel: Instruments

So more likely a fuse? SC16 - 5A left column?

 

[Owain]

There are three buses down
- Convenience: HVAC, Infotainment, Trailer, etc
- Powertrain: engine, ABS, steering angle, airbag, etc
- Dash panel: Instruments

So more likely a fuse? SC16 - 5A left column?

Will check first thing tomorrow, hopefully you are right.
But have been studying the humungous vw wiring diagrams/handbook; trying to relate that to VCDS scans and all those CAN buses. Why in these days where we have to do all online and they have vin and detailed build of vehicle; they can't just give you the info related to JUST your vehicle...

Found most of controllers mentioned in the handbook; but VCDS says J533 CAN GW, J334 imobiliser. Cannot find the J533 or J334" mentioned; also cannot find "gateway" or "gw". Only mention or immobiliser is detection coil into J285.

Is J553 "embedded" in J519?

 

[mmi]

The fuse is still a guess - a kind of "unexplained" but presumably feeding internals of the BCM (thus Gateway too).

As three buses are down, just need find a common factor to all of them.

Is J553 "embedded" in J519?

Correct.
-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519) Labels:. 7E0-937-BCM-V1.clb
Part No SW: 7E0 937 090 C HW: 7E0 937 090 C
Component: BCM PQ25 Max4 H82 0752
-------------------------------------------------------------------------------
Address 19: CAN Gateway (J533) Labels:. 7E0-909-901.clb
Part No SW: 7E0 909 901 HW: 7E0 937 090 C
Component: GW-K-CAN TP20 H82 0752
-------------------------------------------------------------------------------

Found most of controllers mentioned in the handbook; but VCDS says J533 CAN GW, J334 imobiliser. Cannot find the J533 or J334" mentioned; also cannot find "gateway" or "gw". Only mention or immobiliser is detection coil into J285.

I believe the Immobillizer lives in the Instruments - a "Control unit in dash panel insert" J285. But acts as independent/virtual unit J334 on the bus. More exciting stuff on pp. 48-49 "T6 networking concept" in here --> VAG SSP 561 - The T6 2016 - PDF Download

Good luck. Let us know how it progresses.

 

[Owain]

The fuse is still a guess - a kind of "unexplained" but presumably feeding internals of the BCM (thus Gateway too).
View attachment 79121
As three buses are down, just need find a common factor to all of them.


Correct.
-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519) Labels:. 7E0-937-BCM-V1.clb
Part No SW: 7E0 937 090 C HW: 7E0 937 090 C
Component: BCM PQ25 Max4 H82 0752
-------------------------------------------------------------------------------
Address 19: CAN Gateway (J533) Labels:. 7E0-909-901.clb
Part No SW: 7E0 909 901 HW: 7E0 937 090 C
Component: GW-K-CAN TP20 H82 0752
-------------------------------------------------------------------------------


I believe the Immobillizer lives in the Instruments - a "Control unit in dash panel insert" J285. But acts as independent/virtual unit J334 on the bus. More exciting stuff on pp. 48-49 "T6 networking concept" in here --> VAG SSP 561 - The T6 2016 - PDF Download

Good luck. Let us know how it progresses.

View attachment 79120

That is a super manual. This is really what I should have read before starting to tinker. Excellent. Many thanks.

 

[Owain]

Checked SC fuses. Only one blown was SC28, which i was piggy backed off to get IGN for my battery to battery charger.

Replaced fuse did another scan. All units now present. Only errors related to missing trailer controller.

This does not make sense. Sc28 is supply for aux coolant heater relay J493.

???????

Oh well now looking at trailer harness.
As prev said have cut CAN to trailer unit to do voltage/ resistance reading.

But i do not see the expected 60 Ohm between CAN-H and CAN-L.