2003 chevy avalanche heated seats wont stay on

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 perate.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 urselfer. 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.

The purpose of this bulletin is to provide the technician with the following service nformation Heated Seats Switch Operation Heated Seats Switch Diagnostics Heated Seats Switch Customer Information Switch Operation The engine must be running for the heated seat feature to work. The heated seats will shut off automatically when the ignition is turned off.Two buttons, located on the door, are used to control the heated seat. Press the orizontal (RH) button to heat the entire seat, back and cushion. Press the vertical (LH) button to heat ONLY the seat back.The three light bars are an indicator of the level of heat selected for either the entire seat (horizontal button) or ONLY the seat back (vertical button) To heat both the seat back and seat cushion at the same time, press the horizontal (RH) button with the heated seat symbol one time. All 3 light bars will glow indicating the HIGH temperature etting.The horizontal (RH) button does NOT have an ON FF indicator light.Press the button a second time, 2 light bars will glow indicating the MEDIUM temperature setting for the entire seat.Press the button a third time, 1 light bar will glow indicating the LOW temperature setting for the entire seat.Press the button a fourth time to turn the entire heated seat OFF.To heat ONLY the seat back, press the vertical (LH) button one time. An ON FF indicator light over the heated seat back symbol will glow to designate that ONLY the seat back is being heated.All 3 light bars over the horizontal (RH) button will glow indicating the HIGH temperature setting for ONLY the seat back.Press the button a second time, 2 light bars will glow indicating the MEDIUM temperature setting for ONLY the seat back.Press the button a third time, 1 light bar will glow indicating the LOW temperature setting for ONLY the seat back.Press the button a fourth time to turn the heated seat back OFF.Switch Diagnostics mportant: In order to eliminate unnecessary part replacement and comeback repairs, it is essential that the appropriate diagnostic tables and aids found in the applicable manuals are followed.Verify the condition prior to making any repairs. Refer to Seats and Seat Controls in the applicable Owners Manual or this bulletin for proper heated seat switch operation information.If an improperly operating front heated seat condition exists, refer to the Diagnostic Information and Procedures in the Seats sub-section of the applicable Service Manual in order to diagnose the system accurately.When measuring the resistance of the seat heater elements, ensure the values are within the updated range of 1.5-5.5 ohms. Refer to DTC B2425 or B2430-Clearing the DTC in the Diagnostic Information and Procedures in the Seats sub-section of the applicable Service Manual.Customer Information Some heated seat components from the above listed vehicles have been returned to the Warranty Parts Center (WPC) for heat function not operating properly. Analyses of these parts show 'no out of specification condition' or No Trouble Found (NTF)Provide customers with the knowledge that if bumped, either one of the heated seat switches can be activated/deactivated accidentally.Ensure customers have a thorough understanding of how the heated seat switches function.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.