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Middle of installing heated seats; controller won't stay on

April Thompson

April Thompson

New member
I've got the rear seats and the front passenger seat in, along with the HVAC box, but when I tested the seat heater, the two red lights flashed and turned off. I read online that an open circuit (as well as a short) will shut both sides down... as well as temps above 41*F. Well, it was still warmish in my car, and I don't have the driver's heated seat in yet. Will an unplugged seat heater cause the same open circuit condition?
 


I currently have no passenger seat in at all. The heated seat button on the climate control acts like nothing is wrong, lights up and stays lit.
 
And I think the temp limit is 141F, not 41F cause I use mine in the summer all the time with the AC cranked up cause it helps my back.
 
Yeah I was going to say I have used my seat heater on cool summer days before when it was well above 41*. I've also used it to keep my food warm on the ride home from Taco Bell. LOL
 


Will the heaters turn on if no one is in the seat? I also read (in the same article that claims an ambient cabin temp limit of 41*F) that it's sensitive to seat occupancy, and will not activate if the seat's unoccupied. Then, assuming there is a fault and nothing simple sorts it out, what are the usual suspects for causing the seats to not work? All these parts are salvage, so it's anybody's guess whether or not they function... though I've lucked out up until now...
 
I got the final piece of the seating puzzle in... and now my air bag light is on! I made sure the pre-tensioner was plugged in and the lock back in before starting up the car; means there's a break in the wire or a bad tensioner. Either way, I'll be pulling from my cloth seat...
...and the damn heater still isn't working!
 
industrialfish said:
They'll turn on, but I don't think they get warm without someone sitting in them.
Click to expand...

I am almost positive they do. I have started my car with the keys and turned the switch on to let them start to warm up before I took off. I also unplugged the "pressure sensor" on my driver's seat because it kept trying to tell me I wasn't wearing my seatbelt when I was, and the seat heater still works fine.
 
Did your car come with heated seats? I think the BCM needs to be reprogrammed on the 04-08's to add heated seats. The circuit diagram I have shows the wiring that comes out of the buttons as a data line that goes to the BCM.
 


By the way: fixed my air bag warning by replacing the new seat's seat belt pre-tensioner with my old cloth seat's. Turns out the two wires were cut... WHO KNEW?!? :th_wtf:
 
bcmroute_zps84bfe4ca.png


This picture isn't as clear as the one I referenced before (it had color coding and such so it was a bit easier to decipher), but it does confirm that the signal from the switches travel through the BCM. So if I'm correct your BCM would need to be reprogrammed with a Tech II.
 
I'll have to find a garage with a Tech 2, because the local GM dealer has no clue whatsoever about reprogramming the BCM! :th_shakinghead2:
 
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