X5 E53 rear lock, trunk unlock issue

[racebmwm3]

11/04 build

Symptoms
Lately, on cold days, when unlocking the car with the key fob the following is observed:
1. Rear doors do NOT unlock
2. Rear trunk tailgate does NOT unlock using button on tailgate
3. Rear trunk lights (in trunklid) do NOT operate
4. Central lock button on console does NOT operate

When car warms up a bit, everything seems to operate again.

Not sure where to begin troubleshooting.
Fuses?
Modules?
Wiring?

Your assistance is appreciated! My passengers (who now have to jump over front seats to get to back) and my back (which gets wrenched when lifting heavy luggage over the tailgate) thank you!