I have this diagram and the brn 41 has no power with key on. The orange wire 540 does have power all the time. white 1038 is good from star to control head and black 150 is good also. However the green 1038 to PCM has not been tested yet. Tan 63 is good and red 1342 is good and has power. So what should the green wire values be? The a/c would usually come on after a while and usually the first time you start up after that it was if your lucky I really thank you for the help you have offered and hope I can return the same to you one day.

 

If the brown has no power with key on, it should and that is your problem, at least some of it anyway. If you have power across the fuse but not at the head, then broken wire somewhere. Good Luck on finding it.

 

When you put power on the brown wire, did you do it at the head? If you did and you have powers and grounds, then the head is kaput. I would look into that no power on brown wire situation.

 

Let's back up here a minute, as Tim The Tool man says "back the truck up". What is your original problem? I've been going off on a wiring tangent here and maybe going down the wrong road. Is the control not working or is your blower motor not working? Does your compressor come on? Serial data lines are on the communication buss to feed info to the ECM for all variety of inputs to control outputs, not to control your blower motor. It uses serial data on a/c to control idle, injector pulse width, cooling fan control. If you have no blower motor, the blower control module responds to commands from the control head for blower speed via the tan wire circuit 63. I've seen lots of blower control modules go bad, usually the transistor in the module. The red wire is the power feed to the motor and voltage is varied via the transistor in responce to commands from the control head depending on commands you have set into the head, such as temp control, manual override blower speed and such. Hope I have described operation a little more clear for you. Sorry for the novel. LOL