Heated seats won't stay on

truckmann · October 18, 2006

Hi I have a 2003 Silverado with the heated seats and while testing them out before it gets cold outside I have noticed that I am having trouble with them turning off by themself. Seems to be a problem with the drivers side mostly, but when the drivers side has a problem it shuts both sides off. Sometimes it will stay on for a while and sometimes it just shuts off immediatly. Also so far it appears that if I just turn the heat on for the just back of the seat it will stay on, but there is a problem when I try to turn on the whole seat.

What could be the problem here?

If there is something I need to replace can you give me a part number.

Thanks

GM-Tech · October 18, 2006

See if this helps. It would be very useful to know if the codes listed are set. You will have to go to a dealer for this. The type of scanners used at the autol parts stores generally don't read anything but powertrain codes.

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Subject: Heated Seat Inoperative Or Shuts Off In 30 Seconds - keywords B1825 B2435 B2440 B3606 #PIT3287D - (10/02/2006)

Models: 2003-2006 Cadillac Escalade, Escalade ESV, Escalade EXT

2003-2006 Chevrolet Avalanche, Suburban, Tahoe

2003-2007 Silverado Classic

2003-2007 GMC Sierra Classic, Sierra Denali Classic

2003-2006 Yukon, Yukon Denali, Yukon XL, Yukon Denali XL

2003-2007 Hummer H2

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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Driver and passenger heated seats inoperative or shut off in 30 seconds. There will be DTCs B2435, B2440, B3606 and/or B1825 set in the Drivers Seat Module. The adjustable pedal position sensor, seat recliner position sensor and both heat seat thermistors share the same 5 volt reference internal to the Drivers Seat Module. A fault in any of these components/circuits can make the heated seats inoperative or shut off in 30 seconds, as well as, the seat recliner and/or adjustment pedals may move in short increments when operated. A fault in heated seats, adjustable pedal or seat recliner will affect BOTH heated seats.

Note:: Even if the vehicle is not equipped with adjustable pedals DTC B3606 still may set.

Recommendation/Instructions:

To help isolate the area of concern use the Tech 2 and go to "Sensor Data" in the Drivers Seat Module. Monitor the following parameters for being out of range:

Recline Position- Normal range .39V-4.58V

Pedal Position (if equipped) - Normal range .39V-4.58V

Psgr. Seat Heat Sensor- Normal range 1V-4V

Drvr. Seat Heat Sensor- Normal range 1V-4V

If a parameter is found to be out of range inspect circuits for any opens, shorts to ground, or voltage. If none found replace the suspect component.

Please be aware of the following common areas of concern:

The adjustable pedal position sensor internally shorted pulling the 5 volt reference low. Disconnect the adjustable pedal position sensor and see if the heated seats start working correctly, if so replace.

Note Important:: The APP (Accelerator Pedal Position) sensor is NOT the adjustable pedal position sensor. Make sure the correct sensor, adjustable pedal position sensor, is disconnected.

The seat recliner position sensor internally shorted pulling the 5 volt reference low. Disconnect the recliner position sensor and see if heated seats start working correctly, if so replace.

An open in either heated seat thermistor circuits (signal or low reference). The most common is the passenger thermistor where it passes through seat connector C305 pin "L" or "K" or C399 pins "R" or "G".

A chaff to ground on either heated seat thermistor signal circuits. The most common is circuit 5475 black/red or dark blue shorted to ground in the passenger seat near the buckle.

Note Important:: The heated seat thermistors act differently to "OPENS and SHORTS" than the adjustable pedal position sensor and seat recliner position sensor. The adjustable pedals and seat recliner sensors can be disconnected for testing of the heated seats. Where as the heated seat thermistor circuit must be working correctly before EITHER heated seat will operate. Disconnecting one thermistor, which may have a concern will not allow the opposite heated seat to work correctly, BOTH side must be operational before EITHER heated seat will operate.

Clearing DTCs

If DTCs will not clear when using the Tech 2 after a repair has been made, try operating the device in which the repair was made. Example, if a repair was made to the passenger heated seat thermistor circuit, the DTCs may not clear unless the passenger heated seat is operated.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

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truckmann · October 18, 2006

Well I don't know about the codes. Have to find time to get to a dealership. But as an update to my problem I have noticed that the problem only seems to occur when I turn on the whole seat heat on the drivers side. If I just turn on the back heat it seems to work fine. The passenger side appears to have no problems.

Do you think the lower heating element in the drivers side seat might be bad?

If so how hard is it to replace?

GM-Tech · October 18, 2006

It could be the heating element. They'll usually burn out in one spot. You have to remove the seat cover. Some are sewn right into the seat cover. You can just leave the old one in place and set the new one down on the cushion. You'll still get the heat through it, but it will affect the performance somewhat.