2005 Pontiac Montana Q&A
2005 Pontiac Montana Question: Door locks work intermittently. Seem to be related to temperature.
All doors will lock but only driver's side will unlock with any FOB or switch if temperature is warmer. When outside temperature cools down, problem goes away and all locks function normally. Switches appear to work fine and wiring integrity appears fine as well. This pretty much limits the issue to the BCM, although I will check some floor pan wiring as well. Because the issue seems to be related to weather/temperature, it would seem that there is expansion and contraction of a contact, although I still cannot explain how the driver's side fron door still works all the time while the others seem to 'try' to work but don't. - jprobb
ck door lock and unlock relays in relay panel - globalhelper