I'd start by swapping that relay with another one and see if that fixes the problem. We need to know what the actual problem is and what you've tested so far.
Oh, and usually, new folks start out by introducing themselves.
Thanks OldGuy. I'm a mechanic, not a Chevy one though. Mostly Asians (Honda, Toyota).
I would like to test the harness... From PCM to BCM to Fuse box.
P1545 is the DTC
1. Swapped Relays, the relay does not activate, even when using the scanner (Autel Maxisys Elite)
2. A/C compressor works fine when jumped at the #50 Relay.
3. Blower inside cabin works fine.
4. Temp sensor on evap box, jumped the two green wires still didn't work. However, when jumped, the BCM shows the AC request (scanner).
Tons of electrical problems are caused by bad grounds on our trucks. There are 2 main sources of these ground issues, the ground packs mounted on the inner fenders on both sides. One on the passenger's side behind the breather box and one by the ABS module on the driver's side. It's a little box with about 6-8 black ground wires going into each one. I'd make sure they are both tightly mounted to the fender and then I'd open up the little box and check all the contacts inside there. They're usually corroded and not making contact. Most of us have cut that little box off and have put ring terminals on all the wires and mounted them directly to the fender using the bolt that had originally been mounting the box to the fender. You seem to know what you're doing, so if it's not possible that there's a grounding issue, some folks here have had to dismantle the entire fusebox and tighten up all the connections.
Wow! I'm lost on that one. Any other issues? I have no idea what would be the sensor for engine speed. Camshaft position sensor? Crankshaft position sensor? If one of these was sending an odd signal, you would think you would have an error code. No help here man. Sorry.