DTC 01336 - Data Bus for Comfort System - Single Wire Operation

Hi,

My car has a DTC stored in the Instrument Cluster module that will not clear. The code is 01336 and it's description is 'Data Bus for Comfort System 80-00 - Single Wire Operation'.

The Ross Tech website gives the following information, here.

Everything on the car works as it should, and there are no other fault codes stored in other modules. So far, I have tried disconnecting the radio, HVAC unit and CCCU, disconnected and reconnected the battery and unplugged and reconnected the Instrument Cluster - all of these attempts have had no effect.

I would appreciate any help if anyone knows how to fix this issue.

Many thanks,

Matt.

Apologies if you already know this but 'single wire' operation usually works fine and should be no big deal on non critical components.
The two wire function is the means of cancelling out stray 'interference' which could be a real problem if the engine, steering or braking systems went haywire as you drove past the local mobile phone masts or radar station.

A common theme in many VW related forum posts is the drivers side window motor module which seems to be a gateway for many can functions. I've not checked the wiring diagrams to see if it's linked to the instrument cluster but if so, cleaning the multi pin connector and plugging it in and out few times would be worth a try

Cheers Spike

Hi Matt,

I'd agree with Spikes suggestion of checking the drivers door control module. I know at least the drivers door controller does have a role/pass information onto the comfort CAN on the A2 and I have known them to cause similar comfort CAN related issues in the past. Checking the connections to the controllers is a good place to start.

Cheers
Rob


Sent from my iPhone using Tapatalk

Thank you for the information, both.

I'll check out the wiring to the driver's door module and see if the issue is still there when it is unplugged. I forgot to mention in the first post that the CCCU reports the bus as running in two wire mode from MVB Group 16, field 4 - so I'm not sure if it actually is only running in one wire at some point or not.

I'll report back with findings soon.

Thanks,

Matt.

Hi,

I've disconnected and check the driver's door module. There was no change and the fault code mentioned above was still present.

However, before I disconnected the door module, I checked the CCCU for fault codes. The same 'single wire operation' code was present, and the relevant MVB also showed the bus is operating in single wire. This is different to previous scans, and there's nothing obvious that has changed or stopped working. All other modules on the comfort bus have no fault codes stored.

Do you think this is likely a wiring issue or is there anything else that I can try? Is it possible to measure bus continuity/voltage etc?

Thanks,

Matt.

Some light reading (can you have 'heavy' reading) -

http://www.volkspage.net/technik/ssp/ssp/SSP_238.pdf
http://www.volkspage.net/technik/ssp/ssp/SSP_269_d1.pdf
http://www.briskoda.net/forums/topic/111488-no-comms-to-radio-can-bus-single-wire/

Cheers Spike

Thanks for that, Spike.

There is no dead short between either CAN wire to each other, to earth or battery positive. I measured some voltages from the CAN connections at the CCCU connectors on both my TDI with the problem and the FSI, which is entirely free from DTCs.

On the TDI,

CAN-H to GND = 0V
CAN-L to GND = 10.15V
CAN-L to CAN-H = 10.15V

On the FSI,

CAN-H to GND = 0.46V
CAN-L to GND = 10.40V
CAN-L to CAN-H = 11.03V

I'm not entirely sure what to make of the results. The PDFs that you attached suggest the voltage should not exceed 5V, so I'm not sure if it's just a strange meter reading as the voltage is not constant because of the signal. Any advice would be appreciated.

Also, the DTC in the CCCU module is no longer present and the MVB also indicates the bus is running in two wire mode again. This is how it originally was, though yesterday evening it was showing as using one wire.

Thanks,

Matt.

All sorted, I think.

In short, it seems that battery voltage was the underlying issue. When the DTC has been present, the battery voltage indicated on VCDS has been a little low, at around 12 Volts or just below. I've been out this afternoon for a decent run in the car, and the battery voltage has risen to 12.6 Volts - the DTC cleared on the first attempt and has not returned. All is well again.

For future reference, if anyone encounters this issue, I'd recommend checking the battery voltage first.

Thanks for the help,

Matt.

wilco184 said:

All sorted, I think.

In short, it seems that battery voltage was the underlying issue. When the DTC has been present, the battery voltage indicated on VCDS has been a little low, at around 12 Volts or just below. I've been out this afternoon for a decent run in the car, and the battery voltage has risen to 12.6 Volts - the DTC cleared on the first attempt and has not returned. All is well again.

For future reference, if anyone encounters this issue, I'd recommend checking the battery voltage first.

Thanks for the help,

Matt.

Click to expand...

Sorry if this has been covered before but where are the plugs for the driver's door control module please? My driver's window won't stay up when closed until the third attempt: it always winds itself down again a bit.


Sent from my iPhone using Tapatalk

I've just run a scan to trace down the faulty heater flap and discovered on the 'Dashboard section of OBDeleven scanner "Combination Comfort Databus in single wire mode" Fault Code 01336

It also shows up in the 'Comfort System' along with 'Climatronic control module fault code 01320' (status: intermittent) and 'Alarm triggered by door contact switch on frt.pass side fault code 01572' (status: static)

The status shows as 'intermittent' but won't clear.

Odd with code 01320 as I've read this usually means the dash unit is kaput but mine is working OK albeit I've just cleaned out the vents to the air sampler probe in the front (and hopefully fixed the sticking heater flap 01271.

Edit: This is actually a circular post as it links back to the start of this thread.
Have a read of this:
Mac.