Diagnosing Seat Heater (not a short)

bobbfrommn

New Member
This is happening in both my envoys (yes the wife liked mine so much she bought one). The seat pad is out on all four seats but I don't think it's the common pad short/broken wire. I've tested continuity on all of them and no break was detected. In fact to be safe I replaced one of the pads. The old one looked almost pristine and the new one does not work. I'm not sure what my next step is. To summarize:
All door switches light and work as they should
  • The back heaters all work
  • All seat motors work (except one driver lumbar that is on my list)
  • These are 2007 and 2008 Envoy -Denali trim

I've read there are separate controllers (DDM and PDM) in the door for each seat in the older Envoys but can't verify if that is the same for the 07/08. I've gone through just about every seat heater thread on every envoy board I can find. They almost all seem to result in the shorted pad so I'm really not sure what my next diagnostic step is. Does anyone have any suggestions?
 

freddyboy61

Well-Known Member
What do you mean when you say all four seat pads are out? Are you including the seatback heaters as well?
Have you checked the fuse #19 and circuit breaker #8 in the rear fuse box? These are common to the drivers and passenger side heated seats.
 

Blckshdw

Moderator
What do you mean when you say all four seat pads are out? Are you including the seatback heaters as well?
I think he means the 2 front seat bottoms, in both Envoys they own. :undecided:
 
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bobbfrommn

New Member
Yep sorry if that wasn't clear. Two trucks, bottom pad out on each drive and pass seat, the backs work fine. Testing fine for continuity. Pretty sure I checked the fuses but I'll look again.
 

Mooseman

Moderator
The bottom pads always break towards the front thigh area as it passes under a metal foam retainer. Recheck the continuity of the bottom heater alone while you push on the seat in that area. You could try to find replacements at u-pull yards. Passenger side is usually still good as it's usually not used as much.
 

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