No signal to diagnostics port

[Butch]

I've got an unstoppable adblue countdown and when the garage plugged in the main dealer diagnostic kit, it can't communicate with the van. My carista one picks up basics, but can't diagnose the problem.
As you can probably tell, I don't really know what I'm talking about, but 2 separate mechanics with main dealer diagnostic kit have told me the same thing. The signal down both wires to the port is flat. Any ideas? I'm guessing you know @mmi!

 

[Dellmassive]

Two separate problems then.

No data comms with the gateway.

And an adblue fault.

 

[Dellmassive]

What's the adblue issue?

Possibly chewed wires under the van

 

[roadtripper]

Has either dealer or yourself checked the wiring from the OBD port - tampering with the data wires is a common suggestion for frustrating folks trying to use OBD based tools during vehicle thefts.

 

[Butch]

What's the adblue issue?

Possibly chewed wires under the van

Good shout. Did have chewed wires which was triggering Nox sensor fault codes. Replaced, which stopped those codes but didn't stop the countdown.

 

[Butch]

Has either dealer or yourself checked the wiring from the OBD port - tampering with the data wires is a common suggestion for frustrating folks trying to use OBD based tools during vehicle thefts.

Yes, he's followed them back to the gateway but can't test that in situ because it's in such a tight spot and on a short loom.

 

[Butch]

Two separate problems then.

No data comms with the gateway.

And an adblue fault.

Comms would tell us what the adblue fault is, in theory.

 

[mmi]

diagnostic kit, it can't communicate with the van. My carista one picks up basics, but can't diagnose the problem.

Do you mean Carista does get data from the van?

Do you have a multimeter? Please measure voltage (DC) - without key in ignition lock.

(1) between ground and pin 6,​

(2) ground and pin 14.​

​

Can you see the metallic sockets in pins 4, 5, 6, 14 and 16?

 

[Butch]

It's in the garage at the moment. What are you thinking? I could (diplomatically) suggest it. I would think he's covered the multimeter checks as he's had an oscilloscope on it.

 

[mmi]

The proposal was just a simple first DIY check to verify wiring from the socket to the gateway - if you see the voltage (about 2.5 Volts) on both cases (1) and (2) the wiring is good up to the gateway. Of course, doesn't prove the gateway itself is good though.

I'm not sure if the oscilloscope is useful at all as data lines are "flat" as long as there is no communicating device on "this" side of the socket (e.g. diagnostics tester). The gateway doesn't talk to oneself.

Anyways, in the garage they surely know what they are doing

 

[Butch]

I can only hope! Thanks for the explanation.

 

[mmi]

Is the van model year 2019?

Spoiler: Coincidence?

2019 T6 OBD port CAN issue

Hi guys, got a real problem motor here, and thought I'd reach out here just in case anyone has experienced similar. 2019 T6 and no diagnostic comms at all with VCDS or ODIS. It doesn't pick up the VIN. Having scoped the CAN lines on the OBD port, I have around 2.5 volt flat line more or less on...

forums.ross-tech.com

 

[Robert]

The proposal was just a simple first DIY check to verify wiring from the socket to the gateway - if you see the voltage (about 2.5 Volts) on both cases (1) and (2) the wiring is good up to the gateway. Of course, doesn't prove the gateway itself is good though.

I'm not sure if the oscilloscope is useful at all as data lines are "flat" as long as there is no communicating device on "this" side of the socket (e.g. diagnostics tester). The gateway doesn't talk to oneself.

Anyways, in the garage they surely know what they are doing

Quality voltage meter will show slightly over 2.5V between CAN-H and GND and slightly less than 2.5V between CAN-L and GND.

 

[Butch]

Is the van model year 2019?

Spoiler: Coincidence?

2019 T6 OBD port CAN issue

Hi guys, got a real problem motor here, and thought I'd reach out here just in case anyone has experienced similar. 2019 T6 and no diagnostic comms at all with VCDS or ODIS. It doesn't pick up the VIN. Having scoped the CAN lines on the OBD port, I have around 2.5 volt flat line more or less on...

forums.ross-tech.com

Yes it is! T6, not 6.1

 

[Butch]

Yes it is! T6, not 6.1

Not so much a coincidence, now I've read that thread. My mechanic is called Shayne. If someone else called Shayne is posting about the same issue on a 2019 T6 my coincidence detector might explode!

 

[Butch]

Yes it is! T6, not 6.1

Well spotted @mmi