Hey guys, so the Sunday night when I got in my car I turned the ignition to ON and got nothing, no dash lights no instruments no radio. I messed with the ignition a little and got it to come back to life. It happened once more than in the morning it would start at all and wouldnt perform re-learn so I cam to the conclusion the pass lock sensor had failed. I replaced the pass lack sensor and performed the relear and assumed my woes were over. Then last night the dash once again failed to come to life. after an hour of attempting re-learns (security light would not stop flashing) I disconected the battery for 10 mins then put the key into the ignition, turned it to on (no security light was on once key was in on position) i let the key sit for a few minutes and the dash came back to life. Car started 5 or 6 times and then i had to repeat the procedure of disconnecting battery to get the car to start. I scanned the BCM and came up with the Codes B2964 and B3128. I also have a strange electrical issue at times where when i start the car the cruise light will be on and or flashing, the home link wont turn on and the Hvac controls will not work. This condition is remedied by turning on the hvac controls to a position between 1 and 5 and leaving it there for a short period of time. Also rarely my cruise control will simply shut off and stop working and my steering wheel controls for my radio will not work. All this has lead me to believe my BCM is going bad. Any thoughts or help would be appreciated, thanks guys.

 

I'd still go after the ignition switch. It was just widely reported that GM is recalling 7.6 Million more vehicles including the 2000-2005 monte carlo for ignition switch issues. It's not loaded into the dealer system or NHTSA web site yet sadly as it was just reported in the news yesterday.

 

It could be the lock cylinder. I already replaced the ignition cylinder

 

Some people have had luck trying to troubleshoot a failing BCM by throwing it in the freezer for a bit, then once it's good and cold putting it in the vehicle and seeing if the issue goes away until thermal expansion causes a weak solder joint to break connection and the issues to pop back up. If you're good at soldering you might even be able to touch up some of the solder joints/pins if it's just the typical bad/cracked joint.

The best price on a new BCM I've found is on Amazon ($120 with prime shipping) just incase you need it.

 

I pulled the BCM and apart from a possible cold solder joint all ape are in order. It's mostly failed at night however when the Temps are cooler. I can't find a definite way to make the problem happen. But from the codes I'm getting I'm guessing it's not reading the key in the ignition. Do me a favor and tell me what happens to the little red blinky light on your radio when you put the key into the ignition and turn it to on without starting the car? When it won't start it keeps blinking forever. But when it will start mine stops blinking as soon as I go to the on position even without starting the car.