When the key switch for the rear glass fails?
 

Is it the key cylinder that fails typically, or the connector? LMC sells the key cylinder. Wondering if that's the fix. It's not a problem with safety switch. This sucker is acting dead as a door nail.

Re: When the key switch for the rear glass fails?
 

Must be working off the dash if you say safety switch isn't the problem.
Pull lead off the key switch and see if there is power to the switch. Should be hot all the time. If hot, switch is dead or corroded contacts.
Owned & parted over 40 Blazers/Jimmy and Subs and never had key switch be bad. Dash, wiring harness and that dang safety switch for sure but never tailgate key switch.

Re: When the key switch for the rear glass fails?
 

My dash switch bypasses the safety switch. The key switch doesn't budge up or down. That's why I was thinking not the safety switch since I always read it will run one way but not the other when the safety switch is bad. Is that not the case?

Didn't really want to tear the guts out if I could diagnose first. Don't want to wait for parts to come in before repairing. I'd rather do it all at once since the dash switch works fine.

Re: When the key switch for the rear glass fails?
 

Safety switch was so window couldn't be opened when gate was down. Dash or key switch, that window shouldn't open with gate down.
Plug is easy to reach for testing. Drop the gate, pop off the cover plate, undo the cable from the motor and wind out the window with a power drill.
Make sure you have a support for the glass when it comes out of the gate!
Plug is right there.

Re: When the key switch for the rear glass fails?
 

I think we're missing something. Let's play like the tailgate is closed. If the key switch is broken, my understanding is that it wouldn't go up or down. If the safety switch is broken, it will still work down I think. At least based on my reading that's how people diagnose it. Are you observing something else?

My dash switch is not factory and bypasses everything else.