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2003 GMC Sierra Control Panel Issues

557 Views 19 Replies 2 Participants Last post by  Capt Jack
Fan works great but have lost inside/outside air switch, AC switch, and rear defogger with no LED lights. All circuit breakers, relays etc. test ok. Bought a new control panel, plugged it in.....same issue. Could be original panel failed and replacement (new model 599-210xd from Dorman) is also bad out of the box, but what are the chances? Any ideas as I really don't want to pull wire harness if I don't have to.
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Just to clarify your post is it the lights that don't work, or the switches?
The LED lights that light the switches don't ;ight up and other than the fan, the rest of the panel is inoperable.
As I said in my first post, all circuit fuses and relays tested good (every fuse in truck tested by myself and 2 electricians). Fan switch, which is on the control panel, works fine. Second new control panel has same issue. Have to believe problem is in the cable. Hate to tear the dashboard down but it's looking like that is my only option.
Thanks.....I'll let you know what I find but don't hold your breath. As important as it is, it is lower on my to do list than a few other things. I may even use this as an excuse to trade it in. :LOL:

Jack
Thanks Ray. We checked those but we'll check them again.

Jack
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Ray- What are the chances the power for the Control Panel runs through the Throttle Actuator Control under the hood? Part # 12573059 This was just suggested to me by a fellow "familiar" with the vehicle who was a mechanic for 19 years. He refers to it as the vehicles "computer" but I don't see why a TAC would be associated with the AC Control panel. Thoughts?

Jack
Ray-
Dealership wants truck for 3-4 days for diagnosis. Can't (won't) do! Trying to find out what signals the truck's computer under the hood sends to the ac control panel if any. AC control panel has power and ground but only fan works. No lights or button controls for inside/outside air, ac, or rear window defrost. Just wondering if computer (what I earlier called Throttle Actuator Control) is bad in that area. If that's a possibility, it would be worth it to put a new (refurbished) one in. Can't find any wiring diaghrams to show me any connection.

Jack
Ray-
I have that also. Once it leaves the page.......lala land! Just paid a website and downloaded all wiring for a 2003 Sierra 1500. 143 pages (pdf). Will try that approach tomorrow. Thanks!
Jack
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Ray-
Update! Tested wiring cable to Control Panel in dash and found 2 bad wires. When I opened Fuse Box and flipped it over, found rats nest underneath and about 12 chewed wires. The 2 that had bad readings were chewed clean through. Repaired all wires and reinstalled AC Control Panel (my original) Same results. AC and blend doors still didn't work.Swapped out for new panel and now blend doors came on and self programmed but AC compressor would "click" but fail to run. Had refrigerant checked....ok. High and Low pressure switches....ok. Traced every wire associated with AC for continuity.....ok. All fuses and relays....ok. Jumped AC relay (bypassing switches and Powertrain Ontrol Module).....BINGO! Compressor came on.....COLD AIR! With all switches good, all wires good, a compressor that works, it appears the PTM is bad. Probably ran into problems when rat chewed through power line to AC Control panel. Don't know if PTM can be reprogrammed or has to be replaced (blown circuit). Wonder also if I get a new/used one if it will need to be reprogramed to my truck. Starting my research on that now. Any ideas?

Jack
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Ray-

Ordered a module yesterday. The company programs it to my VIN number and advertises a "lifetime warranty". We'll see but it is worth a $185 shot. Fingers crossed but it should work as long as the programming is correct. Thanks again for your interest. Will keep you posted as to the outcome.

Jack
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