Problem connecting to some modules

[EddyH]

I'm having trouble connecting to certain modules on my 2001 Passat. I can connect to the engine, ABS & parking assist modules no problem. However I can't connect to the instruments at all and I connected to the central convenience once but now I can't. There was a fault on the central convenience along the lines of single line data bus mode. Sorry I can't be more accurate but was planning to go back in and get a copy of the fault code.

Any advice on what the problem could be would be appreciated.

[EddyH]

I just wanted to clarify I think this is an issue with the car not VCDS which is a genuine cable running version 908.1 of VCDS.

[fordfan]

I got into 46 on a 2001 Passat estate the other day with no problem, using a Hex/CAN usb lead. That was the only controller we tried as it had a boot opening problem. That was in single wire mode as well.

It is possible that since you tried, the other CAN bus wire has packed in. You may be able to test this if the anti hijack feature or speed related volume for the radio is enabled, as both of these use a speed signal message from the engine ECU that is sent to the convenience ECU.

[bearthebruce]

I just wanted to clarify I think this is an issue with the car not VCDS which is a genuine cable running version 908.1 of VCDS.

My guess is you have a wiring issue. You might try getting access to a wiring diagram on the erwinVW website. Start tracing the wiring from the DLC port. Maybe the wiring information on the Aftermarket Radiopage will be of help - look to the bottom of the page.

[EddyH]

Thanks for the advice so far.

I've now established I can connect to the following modules:

Engine

Auto Trans

ABS

Airbags

Sound System

Radio

Park Assist

I can't connect to these:

Instruments

HVAC

Central Convenience

So it does appear to be a wiring problem. As I have previously managed to connect to the CCM but now can't I think I will start checking the wiring there.

[fordfan]

I may be on the wrong tack here, but could it be a gateway problem?, address 19. It might help if you can find out which controllers are on which CAN system. Engine, Auto Trans, ABS & Airbags - would think would be connected to the drive train CAN, Sound System, Radio & Park Assist may be on the infotainment CAN and HVAC & Central Convenience, on the convenience CAN. This leaves the instrument panel which on some VW group models has the gateway buit into it. I think that you may need to check the continuity on the CAN wires from the convenience unit to the instrument panel. The wires will be a twisted pair of small diameter wire, you already know that one of these is faulty from the single wire fault as previously found.

[EddyH]

Thanks fordfan, I think you're right, good thinking. That hadn't occurred to me but makes sense.