Seat heater

[pdxrealtor]

Until I can round up a tech 2 or the like.....

Does anyone know how to disconnect the heater without pulling one of the fuses or relays that control multiple things.

[[__--MUD--__]]

Seat Heater: Description and Operation
Heated Seats (Front)
HEATED SEATS DESCRIPTION AND OPERATION (FRONT)
HEATED SEAT COMPONENTS
The heated seat system consists of the following components:
- Driver and passenger heated seat switches
- Driver and passenger seat back heater elements
- Driver and passenger seat cushion heater elements
- Driver and passenger seat back temperature sensors
- Driver seat module
- Driver door module
- Passenger door module
HEATED SEAT SYSTEM OPERATION
The driver and passenger heated seats have 2 heat zone operating modules with 3 heat level modes and will operate only while the engine is running.
The heat zones are determined by which of the 2 heated seat buttons are pressed, while the heat level is determined by the number of times they are
pressed. Pressing the seat cushion button 1 time will activate the seat back and cushion heater elements in the high mode. Each time the seat cushion
button 5 pressed the seat back and cushion heat level is reduced from high to medium, low, and off. Pressing the heated seat back button 1 time will
activate only the seat back heater element in the high mode. Each time the seat back button is pressed the seat back heat level is reduced from high to
medium, low, and off. During heated seat operation the heat zone operating mode may be changed without affecting the current heat level mode.
The heated Seat switches are momentary contact switches and are inputs to the driver and passenger door modules. Battery voltage is supplied to the
switch assembly from the door module, and when a heated seat switch is pressed and released a brief switch signal voltage is supplied to the door
module. Whenever the door module receives an active heated seat switch input, the next heated seat operating mode is determined by whatever the
current mode may be. The seat heater elements are controlled by the driver seat module using inputs from the door modules through Class 2 serial
data circuit messages. The driver seat module controls the voltage supply and the ground circuits to the seat heater elements. When a heated seat
function is commanded active, the seat module will switch battery voltage to the heater element supply circuits and ground is provided through low
side drive control circuits.
During heated seat operation both the seat back and cushion heater elements are supplied battery voltage. The seat module grounds the appropriate
control circuits for back only or back and cushion heating modes, and opens or closes the active control circuits as necessary in order to maintain the
desired seat temperature. The seat module relies on inputs from thermistors located in the driver and passenger seat backs to control heated seat
temperatures. The thermistors are 2 wire sensors supplied with a 5-volt referenced signal circuit and a low reference circuit from the seat module.
Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the seat back
temperatures rise. The seat modules allow heated seat operation only while the engine is running which is determined by a Class 2 serial data circuit
message from the powertrain control module.

[[__--MUD--__]]

[[__--MUD--__]]

Just yank that above plug under the seat. The door module is what powers it.

There is a tsb on the heating elements not working all the time when turned on, but I see nothing about them being on by themselfs.

There is updated firmware for the door control module for 2003-2005 that corrects the issue in that tsb. Might try getting a dealership to reprogram that module. All the diagnostics requires a tech2.

[[__--MUD--__]]

****, you have an 06. guess you already have the newer firmware.

[[__--MUD--__]]

Just sitting here thinking... this poped out at me-

The heated Seat switches are momentary contact switches and are inputs to the driver and passenger door modules.

does the physical button face seem loose? Like the spring broke behind it. If the spring broke and its not holding that button open...as you drive around it could be rattling around closing the contact- activating the system.

Here is the input to the drive door module-

[[__--MUD--__]]

Pin #3 & #9 are the actual on/off signals.

In theory, if those were disconnected- you have removed the physical input activators and kept the function indicators operational- Switch is disabled, but you can still see if they are on/off.

Door module communicates to the seat module throught the data bus. Like that heated seat option activated through the bypass module for the remote start...I "think" it contacts the seat module directly through the bus. Dont believe it sends any signal to the door module.

Here's the seat modules-

[HUMTECH]

Good call, never thought of that myself

Originally Posted by [__--MUD--__]

Just sitting here thinking... this poped out at me-

The heated Seat switches are momentary contact switches and are inputs to the driver and passenger door modules.

does the physical button face seem loose? Like the spring broke behind it. If the spring broke and its not holding that button open...as you drive around it could be rattling around closing the contact- activating the system.

Here is the input to the drive door module-

[pdxrealtor]

Right on MUD- all that info is much appreciated!

Now I have to make some sense out of all of it.

RE: the TSB.... In all my Google searching and result reading I did come across the going off automatically after being turned on. Those problems seem to have been narrowed down to the MCM under the seat, and the actual element itself shorting out.

The only problem solver I've been able to find for the on / off ghost is the door module, which is connected to the bottom of the window switches in an 03 Yukon. http://www.fixya.com/cars/t1790846-0...lution-heading


A side from that it's a bunch of 'what I do I do' without a bunch of 'this is what you do' when it comes to auto on/off issues.

I really want to avoid the dealer. I think an acquaintance has a body code reader, but it's not a tech 2. That should work, no?

OH- and RE: the actual switch on the door. That little SOB, when turning on a seat heater at will, will really test a man's anger management issues. I was ready to rip the wires right off that damn circuit board and the only reason I didn't is because I was afraid the heater would still come on leaving me really ****ed.

Anyways, it is removed from the door at this time. I too thought it could be a switch problem because when things go haywire the input of the seat heater BACK button doesn't always register, or is delayed. Once you remove the plastic cosmetic buttons you'll find little low profile rubber buttons attached to the circuit board. I don't think there's a spring behind that. I think it is just the rubber molded the way it is that causes the button to auto return from depress. From what I can see there is nothing wrong visually with the circuit board the switches are attached to.

[[__--MUD--__]]

yea, I call'em rubber nipples

I havn't torn into one of those buttons yet, so I had no clue besides there being some type of mechanical tension...spring, nipple what ever...

If there is some type of short or issue in the memory seat module that is activating the heated seats- I would disconnect the drive door module. Obviously you will not have a visual indicator- if the heating element is on...but you should feel it, and it will also tell you that the door module is NOT what is activating the heated seats.

You will have a completely dead door during testing, but w/ no tech2- I think you can live w/ it for a bit.

[pdxrealtor]

That's a very good point and idea, removing the door module connection.

As for this moment.... I WIN!!! That little mother ****er!

I disconnected the little green two wire connector as shown above and it causes the heater to fault out and not stay on. So if I turn it on it turns off immediately.

Or.... if it decides to come on by itself it shuts wright back off. That damn thing was going bonkers. On and off over and over..... I was so happy to not have to fight it was actually fun to see it spaz out.....

Ya.... I know.... totally mental. That's what that thing will to a man. I think really I'm losing.....

I gotta get to a tech 2 to get rid of the air suspension anyways so that's in the future regardless.

[pdxrealtor]

Can you look at this parts diagram and description and tell me if you think that would include the complete assembly?

I'd hate to end up with just the switches that attach to the casing the circuit board it in.

http://parts.nalleygmc.com/showAssem...modelYear=2006

EDIT--- On a 2003 Yukon I was told the switch and DDM are sold as one unit. I also can't seem to find the DDM as separate unit.

SO... I'm thinking that this must come as one unit.

Here's a couple pics. I don't see any damage or corrosion to the DDM board.

[pdxrealtor]

DDM module, pictured above, and problem is solved.

Thanks for all of your help!