2004 V-70 AWD has an unintended downshift at highway speed. Occurs mostly in wet weather after sustained (3 hours) of driving. Occurance is a loud drivetrain BANG, momentary deceleration, and RPM needle jumps about 500/1000 RPM. Duration of event is less than 1 second and transmission reverts to 5th gear. Information display says LEFT REAR PASSENGER DOOR OPEN, followed by SRS AIRBAG NEEDS SERVICE, followed by ABS BRAKE FAILURE STOP SAFELY. Event will re-occur within 3 to 5 miles. Stopping and shutting off engine resets whatever the cause was and leaves the SRS AIRBAG NEEDS SERVICE on the info display. Message cannot be cleared. Diagnostics (3 times) show nothing.
First event at 88,300. Has occured 3 more times after that about every 3000 miles under the same conditions. V70 has been same dealer serviced since new. Nothing has been neglected that needed repair or replacement including a $1,200 instrument cluster replacement at 94K. The 3rd event was able to get the car diagnosed before the engine was turned off. It was referred to by the Volvo dealer as and active event. DCM also failed at that time. They just shrug their shoulders when they haven't found the cause.
Dave R