VCDS Help (ID Buzz) Module 13 Auto Dist. Reg - Status: Cannot be reached 0100

[drinfinity]

I also took it apart

Maybe don’t mention this bit to VW when you drop it off for warranty work…

 

[markob]

Er no.. although I only opened the plastic box that houses the radar. The actual radar is a sealed module

 

[markob]

The easiest way to test the CAN bus without an oscilloscope is to check the termination resistance. Disconnect your battery, unplug the radar, and use a basic multimeter to measure the resistance between CAN-H and CAN-L. You should see a reading of 60 ohms.

Thanks @Robert - I have now measured the resistance (with the 12v battery disconnected) across the CAN-H & CAN-L - I am getting 120 ohms

 

[Robert]

Getting 120 ohms on the harness means the other termination resistor isn't on that part of the CAN-BUS. The radar unit itself might act as the terminating node. Can you take your multimeter and measure the resistance across the CAN-H and CAN-L pins directly on the unplugged radar?

 

[markob]

Thanks @Robert that’s what I thought..

I’ve tried to measure the corresponding pins on the radar and they measure a dead short. I was in a bit of a rush, so I’ll check again today

Is there a way to confirm the location of the terminating node?

 

[markob]

Had a chance to test the resistance again this evening, some strange results..

 

[markob]

After disconnecting from the car and connecting my multimeter, I initially was able to read 124.5 ohms

 

[markob]

I guess this might confirm the (120 ohm) terminating node is located in the radar module

 

[markob]

However.. whilst taking some pictures the resistance started climbing and showing 271 ohms - from there is was reading up and down

 

[markob]

After leaving it and testing again (5 mins later) it seems to have settled at 131.4 ohms, if I leave the multimeter connected, now it is slowly increasing as I watch it (currently up to 136.3 ohms)

 

[markob]

Found this online - might explain the value climbing :

Resistance increasing while you are taking a measurement often indicates that you are measuring a
capacitor or a circuit containing one. This is usually a normal function of the component, not a sign of failure.

Why Resistance "Climbs"
When you use a multimeter to measure resistance, it sends a small amount of current through the component.

• Capacitor Charging: A capacitor stores electrical energy. As the multimeter’s current flows into it, the capacitor charges up.

 

[markob]

So there’s no DIY solution to this sadly..? I guess I need ODIS to be able to transfer the component protection to a new (or 2nd hand) radar module.?

 

[Robert]

If you plug your radar back in place and then gently pierce the insulation of your CAN-BUS wiring and measure the resistance I expect you to see resistance reading close to 60ohm.
But anyway so far you have verified power supply and CAN-BUS wiring integrity.

Next step would be checking network wiring and the communication. This is going to be very tricky without specific equipment.

I suspect your radar to be kaput.

 

[markob]

Thanks @Robert - agreed, testing the Ethernet side will be tricky. Since reading quite a few VW forums (with similar issues) I think you might be correct, the radar is kaput..

I am booked in with VW for diagnosis in 3 weeks. I have heard they can suggest a faulty radar is a ‘wear & tear’ item and therefore not covered under warranty..