2004 V70R ECU - CEM - DIM most likely

[dneu]

Now, when hot days started, MY V70R developed a strange problem. After driving about 60 suddenly warning light comes up "left rear door open" within a minute a big jolt from drive train and all instruments go dead. Also power windows, turn signals and some AT control. Engine keeps running and I am able to drive car home another 50 miles. Scanner does not show any code - Only prompts "failure to communicate with ECU, ETM, Steering wheel angle sensor and a whole host of other issues. ECU is very hot despite the enclosure fan running. When the car cools down everything returns to normal, not even a single ECU code is stored. A knowledgeable friend assumes DIM need to be rebuilt at a cost of $ 675. But I am a little reluctant to believe it is a DIM issue only.

[doublebug]

I don't think that is DIM.
I'd started with CEM. You can check that with hairdryer.

[oragex]

Usually faulty DIM doesn't pull 'weird' messages. And it's not accompanied by other electrical issues. The faulty DIM was on 2001-2003.

Check the alternator for proper voltage, then check if the sunroof drain works fine. If it's clogged, water will drip onto the CEM behind the dash.