I've had my 04 LeSabre for about 14 months. Seat heater on pass side has always had a problem. Now, just today, I start it up, head to work, and no heat. I go to push the button and its already on HI. Wont switch to LO or off. Pushing the button repeatedly sometimes gets it to cycle through. But seat never heats. I replaced this switch probably 6 months ago, since the backlight went out. Has worked fine since then up until today. The backlight works, I can... get it to switch between modes, but no heat.
Same problem that the pass seat had when I first got it, although the backlight on that switch doesn't work all the time.

How can I test the culprit? Its dead middle of winter, and leather seats plus 5 degree mornings equals a not so nice 45 minute ride to work.
Is it the switch? The seat? A module somewhere? It seems like the switch went bizzerk. But the heat doesn't work at all,no matter what setting I manage to get it to switch to.
Worked fine the whole drive in and home yesterday. Today, nothing. Help??? I'm pretty good with electronics, but I know this car is way outta my league electrically, and my DVOM just isn't gonna tell me what I need to know, most likely.
Where do I start, what do I test?
Can the switch work, with a blown fuse or circuit to the seat itself? Or does the switch have some sort of feedback loop from some control circuit in the seat?
I put heated seats in my 01 Cruiser that didn't have them originally, and it was simply hooking up 12v and ground. All the electrics were contained under the seat itself. And any faults in the system show up as a blinking light on the seat switch. This.. is way over my head. I have no idea where to start testing?

https://www.gmforum.com/showthread.p...eated+seat+fix

im not to familar with heated seats but check that thread it may be a starting point..i would test power on pretty much every wire first off and if all checks out its bound to be a ''part'' that is your issue...I know jack about heated seats but its still all the same principal

Your heating elements are the same type as in the link. Your module though is different, along with the switches. (not that i posted those). The most common issue would be you press the switch to on and it almost immediately turns back off. That is the typical bad element in your system.

I'm kinda unsure. Should be able to check the FSM tonight though.

Nope, its either stuck in HI LO or off. I have to repeatedly press the button to get it to cycle. But no matter if its actually displaying a HI or LO command, the seat heater doesn't work.

The FSM talks about there being a fuse in the rear block for each heater. It says something about the DDM commanding a class 2 bus signal from the RIM to pulse a signal to turn the seat on. WTF?
What happened to on and off? Seriously.
The fuse in the rear is the only one that seems it could be out. Other than that, its all a DDM and RIM and seat heater module communication mumbo jumbo that I can't properly test.

And to top it off, we just got slammed with a a huge band of lake effect snow, probably a good 8" on the ground now, more just keeps dropping. ....and it was supposed to be 32 degrees and my day off today and nice and ..... grrrrrrr. Damn snow!

I mean, I can test a bunch of things. Test for power, test for ground, etc etc. But man, I have nowhere to work on this car, especially when it snows. I basically park on the street in winter, so this really sucks.

Yeah all that dash integration module and rear integration module stuff is pretty odd. Mostly it'* used to supply power, in the same type of way the ignition circuit would power a couple of relays for all the accessories.

Ok, after going out to unbury my car from about a foot of snow...

both sides now do the same thing.
Press switch, goes to HI. Nothing happens. Switch stays on HI. Press switch again, and I hear a "click" from the heated seat modules, but no change to switch. If press the switch over and over, eventually it cycles around. But thats all I get. Both sides do the same thing. Checked the fuses labeled for the heated seats in the rear fuse box, both are good, not blown.
Now what?

This is going to seriously suck not having heat. Today will be the first morning driving into work where the temps are in the negatives... and no heat. Aw maaaan. Its 5 below out there now, and my seat heaters just go out? Really??? I hate winter!

Seems like you live in the wrong place...lol

I'll try and look tonight. Sorry last night got boogered and I had to go fix a jukebox.

Right place, just wrong time of year, Bill. lol.
I checked both fuses, one for each side. Both ok.
I checked the Ign3 circuit fuse (can't remember what role it plays in the heated seats, but it shows up in the power distribution diagram) and it checked out ok.
I checked both wiring connectors at the seat module, and both are in securely.

Again, the pass side switch has always done this, and I've never really gotten around to fixing it. Just figured the switch was stuck, and I almost always drive by myself, so it wasn't a big issue.
Driver side switch is brand new GM, that'* only been in there 6 months ish. I only replaced it because the back light for it went out, and I was replacing all the stuff in the car (HVAC control, steering wheel buttons, etc) where the backlights were out. The switch and heated seats still worked fine. So I do have a known good switch as a spare. If I had room, I could take the door panel off and just try it to see, though I highly doubt its the problem.

And as far as I can tell, I can't get heat from it, even if its on HI or LO. It just seems to stick, and when I push the button the module clicks. The light doesn't blink, or turn off.
Its definitely not in a load shed 2 state, and even if it were, state 2 shuts the seats off completely, along with the indicators, so the switches wouldn't even show up as being on at all.
I looked through both my FSM, and the ALLDATA online section for the same thing. From what I can tell, it sounds like the modules are bad, because I don't think the HI or LO indicators would be on if there was a malfunction in the heaters themselves. If I had a space to work, I could probably test resistance of the heaters to check for an open circuit. I hate to replace the modules if the heaters are out. Its pretty cramped under there, and the connections to the modules aren't gotten to easily.

But again, its my day off, I have some errands to run, and we are expecting a decent snowstorm today.
Ya know, if I could afford a snowmobile, Id love this weather. I don't mind it too bad, I just hate not having a place to work on my cars this time of year. If I had a nice heated garage, or even one of those canvas shelters with a kero heater, I'd be a lot less grumpy...lol.

I noticed also when I got home earlier, that the module will keep trying to turn it on. If you put the key in run, and push the seat button, HI lights up, and the module clicks, then again. Waits a few seconds, then tries it again. Same if I get the button to LO. It will keep clicking, like its trying to turn them on. It clicks every time I push the button manually as well, even if HI is already on.

Let me guess.. my seat heaters are all an open circuit now, and to get them working I have to rip the interior of my car all apart, in the middle of the road, in the middle of upstate NY winter, to solder some stupid wires back together.

Ok, so maybe not that extreme... but man, with my back problems, and having anywhere from a 45 minute to an hour long commute one way, the heat really helps my back, and keeps my back muscles from being so tense. I put in one of my old Homedic massage and heat seat cover things the past 2 days, and its just not the same.