: Front seats no heating and cooling / 05 STS



FSchuett
05-24-11, 02:59 AM
Hello,

Both front seats are not heating and cooling.
All fuses are OK and at the climate control display
for cooling and heating seats are off.

Anyone an idea ?

If search in the STS forum and I found nothing.

Thanks.

With best wishes from germany
Frank

1BadCadSTS
05-24-11, 09:10 AM
When you say are off do you mean when you press the button they do not light up?

FSchuett
05-24-11, 09:33 AM
Yes...

1BadCadSTS
05-24-11, 10:13 AM
this should help...

Heated/Vented Seat Description and Operation
The driver and front passenger heated seats each consist of the following components.

Heated/Vented Seat Switch
Heated/Vented Seat Module
Seat Cushion Heater Element
Seat Back Heater Element
Temperature Sensor
Memory Seat Module (MSM)
Climate Control Panel (CCP)
Seat Cushion Blower Motor
Seat Back Blower Motor
LF FRT HTD SEAT MOD 20 A
IGN 3 Fuse 10 A
Power and Ground
Battery positive voltage is supplied to the heated/vented seat module from the rear fuse block IGN 3 Fuse. This voltage is used to power up the heated/vented seat module allowing the heated seats to operate only when the ignition switch is in the ON position. Battery positive voltage is also supplied at all times to the heated/vented seat module from the LF FRT HTD SEAT MOD fuse located in the left rear fuse block This voltage is used by the module to supply power to the seat heating elements and blower motors. The module is grounded through the module ground circuit to a ground stake.

Heated/Vented Seat Switch
The driver and passenger heated/vented seats are controlled by separate heated and vented seat switches located in the climate control panel (CCP). When a heated or vented seat switch is pressed, the CCP sends a GMLAN message via the serial data line to the MSM indicating the heated or vented seat command. In response to this signal, the MSM sends a low side PWM signal through the appropriate driver or passenger heated/vented seat mode signal circuit to the heated/vented seat module. The heated/vented seat module then activates the appropriate heated or vented seat mode. The MSM then sends a GMLAN message back to the CCP to illuminate the appropriate temperature indicator.

Heated Seat Operation
When the ignition is turned to the ON position, the heated/vented seats will initialize in the OFF state. When the heated seat switch is pressed once, the heated/vented seat module applies battery positive voltage through the heated seat element supply voltage circuit to the seat cushion and seat back heating elements, initially setting the seat temperature to high heat. Then with each additional activation of the switch, the heated/vented seat module will cycle the temperature setting to MED, LOW, and OFF. The heated/vented seat module will also turn off the heated seat function whenever the ignition switch is turned to the OFF position.

Temperature Regulation
The heated seat system is designed to warm the seat cushion and seat back to approximately 42C (107.6F) when in the high heat position, 39.5C (103.1F ) when in the medium heat position, and 37C (98.6F) when in the low heat position. The heated/vented seat module monitors the seat temperature through the temperature sensor signal circuit and the temperature sensor (thermistor) that is located in the seat cushion. The temperature sensor is a variable resistor, its resistance changes as the temperature of the seat changes. When the temperature sensor resistance indicates to the heated/vented seat module that the seat has reached the desired temperature, the module turns off the element supply voltage to the seat heating elements. The module will then cycle the element supply voltage on and off in order to maintain the desired temperature.

Vented Seat Modes of Operation
When the ventilation seat system is active, it is designed to draw cabin air around and away from the occupant through small holes in the seat cushion and seat back covers, through channels in the foam pad, and then through the blower motor exhausting the waste air under the seat cushion.

Battery positive voltage is supplied at all times to both front passenger seat blower motors from the RF Heated/Vented Seat Fuse located in the right rear fuse block. Both, the driver seat and passenger seat blower motors are grounded through their ground circuits and G307. When a vented seat switch is pressed, the heated/vented seat module sends a low side pulse width modulation (PWM) signal through the blower motor control circuits to the seat cushion and seat back blower motors indicating the vented seat command. In response to this signal, the logic in the blower motors set the blower speed to the switch set point. Both blower motors then run drawing cabin air around and away from occupant. The following describes the High, MED, and Low ventilation modes of operation:

High Ventilation This mode cancels all previous modes and initiates a ventilation cycle with the Under-Cool and Super-Cool Features active. See below for the description of these features. In the high mode, both the seat cushion and seat back blowers are ON at a 95 percent duty cycle that provides 100 percent blower performance.
Medium Ventilation This mode operates identical to the High Ventilation setting with the exception that the blowers are ON at a 85 percent duty cycle that provides 80 percent blower performance.
Low Ventilation This mode also operates identical to the High Ventilation setting with the exception that the blowers are ON at a 75 percent duty cycle that provides 60 percent blower performance.
During vented seat modes of operation, the heated/vented seat module uses Under-cool and Super Under-cool Features in order to keep the seat temperature above pre-determined set point temperatures. The following describes these features:

Under-Cool Feature The under-cool feature set point is 15C (59F). The heated/vented seat module under-cool feature is active when the system is in any one of the 3 High, MED, or Low ventilation modes. The under-cool feature will initiate a heat cycle when it detects that the seat temperature reached it's set point of 15C (59F). This means that if the seat temperature reaches this set point, it is possible for both, the blowers and heaters to be on at the same time. Then if the control module does not detect that the operating temperature is above the set point within 90 seconds of the initiation of under-cool mode, the module will shut down and cease operation.
Super Under-Cool Feature The super under-cool feature set point is 10C (50F). The super under-cool feature is also active when the system is in any of the three ventilation modes. This feature is meant as a secondary precautionary measure. The super under-cool feature will deactivate the blower motors and initiate a heat cycle when it detects that the seat temperature reached it's set point of 10C (50F). This means that it is possible for the seat heaters to be on and the blowers off while in the ventilation mode. If the control module does not detect that the operating temperature is above the set point within 90 seconds of the initiation of super under-cool mode, the module will shut down and cease operation.
Load Management
The ON/OFF status of the heated seats is reported to the rear integration module (RIM) through the status output signal circuit of each heated seat module. During Heated Seats Load Shed Level 1, and the RIM recognizes that the heated seat status signal is active, it will cycle the heated seat operation 16.0 seconds ON and 4.0 seconds OFF. During Heated Seats Load Shed Level 2, the RIM will signal the heated seat module to cancel the heated seat operation and send a class 2 message to the climate control panel (CCP) to turn off the appropriate heated seat temperature indicators.

FSchuett
05-24-11, 11:25 AM
Boahhh,
thank you very very much...
I hope this should help me.

Thanks

Frank

gmcygan
09-14-11, 02:10 PM
hello Frank,
given this detail description of operation were you able to find and fix the problem?
I have simmilar issue with my 2005 STS ....no Fan in the driver's side seat.
thanks, George

gmcygan
09-14-11, 02:13 PM
hello 1BadCadSTS,

you must be a Cad certiified mechanic.
Great description, but do you have any suggestion about diagnosing this problem.
In my case ...I have no Fan operation in the driver's side seat.
thanks, George

jasonjsimon
11-21-11, 01:34 PM
Sorry for bringing back an older thread, but I also have this problem with my drivers seat - no heat or cooling. Lights illuminate properly, but don't get any response. All the other power mechanisms in the seat are working fine though. Anyone come up with a procedure to diagnose?

allen sumwalt
11-21-11, 02:11 PM
the seat control module under the driver seat buttom will probly be the problem does the memory seat functions work.

jasonjsimon
11-21-11, 03:02 PM
the seat control module under the driver seat buttom will probly be the problem does the memory seat functions work.
Okay, just came back form re-checking all fuses in the car with a meter and all are good. Yes, the memory seat functions all work perfectly. Does that rule out the seat control module? If not, any suggestions on how I can diagnose that? I had a look under the seat just to make sure there were no loose connections and boy is it tight under there. I didn't find anything of interest, but if there's a way I can check the seat module, that would be great. It's getting colder and it sure would be nice to get this working.
Thank you!

jasonjsimon
12-04-11, 12:16 PM
Does anyone have any knowledge or experience with this problem? To recap, my 2005 STS driver seat has no heat or cooling. The buttons work fine and the lights illuminate just as you would expect - but no heating or cooling. (Passenger seat works great.) I checked every single fuse in the car and they are all good. I also checked the harnesses under the seat and they all seem to be seated well.

As a side note, the steering wheel heat doesn't work either. No indicator light either when I press the heat button on that. Not sure if there is any relation to seat problems...

Any ideas?

Thank you.

dkozloski
12-04-11, 04:13 PM
Sounds like a flood car. Did it ever work? Did you buy the car new?

jasonjsimon
12-04-11, 05:08 PM
Car is very very clean, but I did buy it used with clean history and title. These were the only problems the car had when I bought it a few months ago. I was able to use these to negotiate the price down a bit, but now I'd like to get them fixed - it's getting cold here!
Flood or no flood, I can't imagine the heating and cooling of a seat being all that complex. I just don't know what to try next.

dkozloski
12-04-11, 05:56 PM
A good place to start is to buy a Factory Service Manual or an AllData subscription.

Smiling Jack
12-04-11, 07:05 PM
My new (to me) 2006 STS has no heat on either driver's side or passenger's side. Similar to Jason's post, my controls seem to be working and the console indicators light up properly, but there's just no heat.

Is this a common failure?

jasonjsimon
12-21-11, 03:59 PM
My new (to me) 2006 STS has no heat on either driver's side or passenger's side. Similar to Jason's post, my controls seem to be working and the console indicators light up properly, but there's just no heat.

Is this a common failure?
Sure wish I could find an answer to this. Have just done a little bit of reading on similar symptoms of mine (no heating or cooling) in the Escalade. That's commonly a bad seat control module as Allen stated above. I'm beginning to suspect that. I wonder if I could swap the driver module for the passenger module.... that is after I figure out where it is located.

thewade44
01-06-12, 12:57 PM
Mine is the same thing. No heat or cool. The light comes on like it is suppose to work but nothing. The dealer is trying to charge $700 to replace the heating elements and I'm trying to tell them its not that cause the cool feature doesn't work either. More to come

ddalder
01-06-12, 03:36 PM
Mine is the same thing. No heat or cool. The light comes on like it is suppose to work but nothing. The dealer is trying to charge $700 to replace the heating elements and I'm trying to tell them its not that cause the cool feature doesn't work either. More to come
You may not be entirely correct here. Looking over some of the technical documentation, there are times that heating and ventilation are on simultaneously.

In general, this system can be difficult to diagnose without a Tech2. The switches on the HVAC control head simply command the HVAC controller to send a data bus signal to the seat modules. Ideally, it would be nice to scan for codes and perform some testing functions such as commanding the heat/ventilation on using the Tech2. Different techniques and tools allow for faster and more effective diagnosis and repair. What many people don't understand is the actual level of technology in these cars and how the different systems function together. Troubleshooting is frequently difficult without the correct resources.

MacMuse
01-06-12, 05:41 PM
Still wouldn't hurt to check the fuse. ;)

ddalder
01-06-12, 05:43 PM
Still wouldn't hurt to check the fuse. ;)
Completely agree. Always the best place to start.

jasonjsimon
01-20-12, 04:31 PM
Mine is the same thing. No heat or cool. The light comes on like it is suppose to work but nothing. The dealer is trying to charge $700 to replace the heating elements and I'm trying to tell them its not that cause the cool feature doesn't work either. More to come

So what was the outcome? Very anxious to know what they found...

Imsys
01-23-12, 12:21 PM
Didn't read all the threads on this, but I had the same issue and it turned out to be the connector under the drivers seat... diconnect and reconnect everything under the drivers seat, then replace the burnt out fuse under the rear seat passenger side... You'll need to do this every few months.

jasonjsimon
01-23-12, 04:33 PM
Unfortunately for me, all the fuses are okay and I have already reseated all the cables under the seat but it didn't solve the problem. Hoping there is another failure point I can check myself before having to take it to the dealership.

jasonjsimon
05-23-12, 10:28 AM
Mine is the same thing. No heat or cool. The light comes on like it is suppose to work but nothing. The dealer is trying to charge $700 to replace the heating elements and I'm trying to tell them its not that cause the cool feature doesn't work either. More to come
Did you ever figure out what was causing your issue? I have the exact same problem as yours and I'm curious if the dealership fixed it and if so, what did they end up doing?

curtc
05-23-12, 10:56 AM
If the heating and cooling feature are not functioning one can probably assume using simple logic that the heating element isn't the issue...Also, don't EVER bring your car to a dealership to replace a burnt out heating element...Find a reputable upholstery shop and it will be done at 1/3 the price...I guarantee it.

1BadCadSTS
05-23-12, 01:25 PM
Unless its under warranty then take it haha

My 05 seat wasn't heating or cooling. They replaced the lower element bag which is also part of the cooling system and it's been fine since.

curtc
05-23-12, 01:56 PM
Unless its under warranty then take it haha

My 05 seat wasn't heating or cooling. They replaced the lower element bag which is also part of the cooling system and it's been fine since.

touche :)

jasonjsimon
05-23-12, 03:25 PM
Would you mind expounding on what the lower element bag is?

1BadCadSTS
05-23-12, 03:35 PM
I'm in obx nc right now or I'd scan a copy of the serivce order but it looks like a white burlap bag and the air blows in it and out through the porous material into the seat. I believe the electrical wire element is also in it. Not sure now exactly it works I just know same issue with mine and the lower element did fix it. Trust your dealer if they don't fix it you just got a free repair.