Hi,
The easiest way for me to explain this is to explain the circuit.
Power is supplied directly to the blower motor from the HVAC blower fuse via the red/white wire. You have power there.
Next, power goes through the blower motor, the resister, and then the switch in the vehicle. However, in the off position, the switch is open and no power flows. When you select a speed, for example, high speed, a ground path is provided by the switch directly to the purple wire between the relay and its ground. That would be high speed.
If you look at the pics below, I attached the wiring schematic and highlighted all wiring involved.
When you select low speed, power goes through the resister via the yellow wire to ground.
When you select m1, power then is routed through the resister via the tan wire to ground.
When you select m2, power is routed through the resister via the light blue wire to ground.
And then high is a direct 12v line via the purple wire.
Inside the resister is where the speed is actually controlled via different levels of resistance in the blower motor resistor. The different resistances control the amount of voltage allowed to run through the motor. As a result, the fan speed changes.
So, to answer your question, yes power should be at the purple wire out from the motor. From that point, there needs to be a ground completing the circuit and that is decided by the switch, the blower motor relay, the BCM HVAC fuse /inside of the vehicle center of the dash, and then a good ground located on the lower left side of the dash fuse box (black wire).
Okay, I attached the schematics below, and let me know if anything I said makes sense. LOL, I never know if what I'm saying makes sense to others when it is read.
Also, here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-wiring
Take care and let me know what you find or if you have other questions.
Take care,
Joe
See pics below.
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Friday, January 7th, 2022 AT 9:57 PM
