Blower fan not working

The diagrams are quite different from the factory manual drawings. The module has 4 terminals: hot power, ground, input signal, and output voltage. I have checked those things. My concern is the input signal from the HVAC programmer. With the module disconnected, the signal reads 8.2 volts instead of a variable voltage as the speed button is changed. If that were true it shows the programmer is at fault. But all the door functions work normally, except blower fan. I guess my next step is to back probe the input signal when the module is connected. The symptoms indicate a bad module, but only if the input signal checks okay. My module is ACDelco 15-8684.

The blower feedback fuse 11 in the relay center checks good. The factory flow chart says the input signal voltage should be between 6-8 volts, definitely not less than 6 volts. So that checks okay. I am 99% certain it is the blower control module. A new module is $200.00 plus shipping to Canada. Since I am also an Electronics Tech, I am going to replace Power Transistor.

When the module is disconnected, I believe the input signal just shows a standby voltage since there is no blower feedback signal. Getting closer!

I ordered a new module from RockAuto, after soldering in a new power transistor did not work. Now it works great. During my initial testing I spun the squirrel cage blower by hand to confirm that it was not tight or seized. I also applies a direct 12 volts to it. All was good.