Got a 2006 XC90 with a fuel cap that will not lock since the last fill up. It has been working up until now, had the vehicle almost 3 years. What I've done so far:
1) Checked for power at motor solenoid connector (blue/black stripe to yellow). I got 0 volts after locking and unlocking door several times. Even tried hooking up meter and drove around the block to see if voltage is getting to motor because I know there's a speed component in this thing locking, read 0 volts. Not sure if the 10 minute delay is involved on this year XC90 or not. Regardless, not getting power to motor at all.
2) Checked for ground at plug. Read good ground from the two yellow wire pin to ground.
3) Researched wiring diagrams and found that lock motor is designated component 6/37 with power coming from 4/58 (REM) pin B9 and ground from REM pin B26 and RH rear door lock unit 3/77.

Question is, since I have a good solid ground reading all the time, it's awaiting power to energize solenoid to lock fuel door. Assuming the wiring is OK (I have not yet gained access to REM to ringout continuity since that involves tearing apart half of the rear interior) does it mean that the REM is bad? I mean it's supposed to output 12 volts from B9 but is consistently not doing that. Any way to do further tests?

Thanks in advance!