Hi all,
I've recently bought an 09 XC60 with a known issue. It was sold advertising a broken Central Electronics Module however after spending a bit of time reading the wiring diagram and then measuring a few electrical things, it appears to have a short circuit in the intermediate speed CANBus. Every system on the Intermediate CANBus diagram is not functioning and when I measure resistances with a multimeter I am seeing a short between violet/orange and grey/orange on every device I've measured. Weird thing is that it is showing the correct 60 ohms at the OBD2 plug, but a short in the instrument cluster which is right adjacent to the OBD2.

The Scan tool i'm using is an iCarsoft CR pro and is reporting that it can't talk to CEM. I'm assuming that CEM would be highest priority on the bus so even though the whole bus is down it's only complaining about that thing. The car runs and drives great, the engine, gearbox, lights, indicators, brakes, ABS all work.

The instrument cluster, infotainment, seats, windows, locks are all broken. The cluster is just blank

There's a large plug on the passenger side (RHD car) that when I unplug it, the Intermediate CANBus resistance returns to almost normal. It heads down the rear but I have not been able to isolate the problem further along the loom.

I've pulled most of the interior out of it to try to find damage to the wiring loom as it is possible that a rodent has been in the car based on the environment it was stored in it's previous life.

The only thing I've found is evidence of rodents around and under the battery

Just wondering if anyone has any recommendations on how to work out where the problem may be?

Thanks in advance, any advice would be very much appreciated

 

Replying to myself, after pulling more of the interior out I'm still drawing a blank. I did find a dead rat in the engine bay under the plastic cowl covering the wiper arms, it had been there for a couple of years. The loom around the engine management computer was a bit dirty so I've cleaned it up with a pressure sprayer and liberal wd40. Car still runs and drives fine but no change to the Intermediate speed CANBus.

The issue seems to be in the back of the car. If I unplug connector 74-504 which is above the CEM, the short goes away on one side of the plug but is still present in the direction of the back of the car.

Does anyone know where the CANBus termination resistors are in this car? Or is there a module that has the resistor?

Any chance someone might measure the intermediate CANBus resistance at the instrument cluster, CEM or elsewhere?

Thanks

 

Found the short, located on the PCB of the driver's seat control module which was manufactured with a daggy solder job between CANBus tracks.

Gutted the interior to work that out, didn't find any loom damage. Worked counterclockwise from passenger seat pulling everything apart (RHD) and just kept checking for the presence of the short as more and more stuff was unplugged while also looking for wiring damage.

When the driver's seat was unplugged and the loom resistance between CANHi and CANlow was checked I saw for the first time the correct resistance so I refitted the battery terminal and then the instrument cluster lit up and I knew I'd found the problem.

There was a Rat under the plastic wiper cowl in the engine bay. At least 2 years dead, with a lot of droppings so pressure washed everything.

Took a solid 1.5 days to get everything reassembled, cleaning as I went.

 

I have a 13 xc60 with an unusual "Non-Sleeping 0855mA" Intermediate CAN bus issue. Volvo dealership after 20 days gave up. They tried to update the ICM but could not. Not sure why an update to the ICM would solve the issue. Everything works but it never goes into sleep mode. All fuses good, Brace/loop installed, new Alternator etc. I have a breakout box, DMM and power supply to trouble shoot with. Any possible suggestions.