I've never heard of a TCM (your Blazer doesn't have a Transmission Control Module), but there is a TCCM (Transfer Case Control Module). I doubt that's the problem, though.

You might have to have the new BCM programmed for your vehicle by a dealer, but I'm not sure. Maybe Les or somebody else who's smarter than I am about this stuff can chime in here.

 

New Stalk assemblies are fairly cheap from dorman,
65$ and free shipping. this is some weird gremlin if i've ever seen one.

 

Thanks much, Mods. My last diagnosis found that if I barely depress the hazard warning switch (which works backwards , in for off, out for on) it cures the problem. I have a multifunction switch coming from ebay, just have to figure the best (easiest) way to change it. Do I have to pull the steering wheel? I tried to get at it by trying to remove the surrounding housings, but struck out on that one! Chuck

 

best bet in your case is to jack the front of the truck up and get it on jack stands so you can turn the wheel without starting the motor.
I'm not familiar with the process but chances are you will need to pull the wheel just based on where the switch assembly mounts. Start by pulling the airbag (it just pushes out from spring clips behind the wheel, this is why you need to turn it), Unhook the battery and wait half an hour, then remove the airbag and set it somewhere safe FACE UP and away from tools, people or anything flammable. then crack the nut loose, its optional but best to lock the wheel by jiggling it a bit and then break it loose. afterwards use a paint marker to mark the splines and wheel so it gets installed in the right place.

Rent (or buy, i recommend renting if you dont do this often) a steering wheel puller set and pull 'er off. Then remove the clamshell around the column, there are 3 bolts on the underside, ones an inverted torque that you can use a small (between 6 and 8mm) socket to remove, and a hing at the back, dear god i hope you have a tilting column for this part. From there it should be visible how it goes together, if you have to remove the clockspring just be careful that you disconnect the wires and dont rotate it at all (tape it in place if you must), if you do then just reset it back to center and it will align itself.
That should be it. Good luck.

 

Thanx much, MODS. I'll study the info and give it a shot when my switch comes in, Chuck

Just like you said, MODs, but with a super video that is good enough to be a sticky! , Chuck