GMC Troubleshooting Questions? Ask a Mechanic for Answers
good morning my name is ***** ***** I will assist
let me get a wiring diagram for you
ok check the diagram I sent you and verify the 2 fuses listed have 12 volts on each side.
you said the output was low??? which wire did you measure???
ok, what about the brown wire???
seat controls??? I thought we have an issue with the rear blower???
this is an input wire to the resistor. not at motor.
sorry, I sent you manual control.
check this one
is there any voltage on the ppl wire from the module to the resistor???
it is pointing to the hvac control module in the rear. that get a signal from the front from a serial line.
do you have a scan tool to monitor the ac controls???
no, the noise comes from the plastic gears in the motor failing. that will need to be replaced as well.
you need a full blown scan tool, not a code reader.
serial lines carry very low voltage. it is not something you measure with a volt meter
you have power into the resistor from the fuses.
thats why you need a scan tool to see if the signal is getting back to the module. in most coses, it is the module that is the failure as that controls the fan speeds through the resistor
no one rents a full scan tool. they cost about 3 to 5k.
you could at least have someone look at it and finish the diag and confirm the module. at least you will know and then you could complete the repair to save money. it would be ell worth the 150 for the diag.
let me see if I can find a picture
good, glad you found it
I feel confident based on your info that is the issue
please dont forget to rate me as it is the only way I get paid for my efforts
thats another reason you need a scan tool to monitor the controls as I stated before.
when the module in the rear turns on, then it will say on. that signal comes from the rear module
ok, thats good. the question is, why did it not work. re setting is not a repair at all. if it went out once, it will continue until there is no more re setting
the actuator will not shut down the module. there are stops on the mode door. when the motor hits them, that is what causes the plastic gears to fail. very common failure