• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Driver Heated Seat Sensor Signal | B2435 | B2435 | B2435 | -- |
Passenger Heated Seat Sensor Signal | B2440 | B2440 | B2440 | -- |
Driver Heated Seat Sensor Low Reference | B2435 | B2435 | B2435 | -- |
Passenger Heated Seat Sensor Low Reference | B2440 | B2440 | B2440 | -- |
Driver Seat Back Element Voltage Control | B2425 | 1 | B2425 | -- |
Driver Seat Cushion Element Voltage Control | B2425 | 1 | B2425 | -- |
Driver Seat Back and Cushion Element Low Reference Control | B2425 | 1 | B2425 | -- |
Passenger Seat Back Element Voltage Control | B2430 | 2 | B2430 | -- |
Passenger Seat Cushion Element Voltage Control | B2430 | 2 | B2430 | -- |
Passenger Seat Back and Cushion Element Low Reference Control | B2430 | 2 | B2430 | -- |
1. Driver heated seat inoperative. 2. Passenger heated seat inoperative. |
The driver and front passenger heated seats are controlled by separate heated seat switches. The switches are located on the door panels. When a heated seat switch is pressed, B+ is momentarily applied through the switch contacts and the switch signal circuit to the door lock/window switch. In response to this signal, the door lock/window switch sends a serial data message to the memory seat module (MSM) indicating the heat seat request. The door lock/window switch then illuminates the appropriate heated seat switch indicators.
The left and right heated seats are controlled by the memory seat module (MSM). When active, ground is applied to the seat cushion and back heater elements through a common low side drive low reference control circuit. Battery voltage is applied to the seat cushion and seat back heater elements by the MSM through separate high side drive control circuits. In the back only mode, the MSM applies battery voltage to just the seat back heater element, not the seat cushion heater element. The heater element control circuits are pulse width modulated to B+ by the module in order to control the seat temperature by regulating the current flow through the heater elements. The module then monitors the current flow through the heating elements and the of rate change of the temperature sensors to verify correct heated seat operation.
Heated Seats Description and Operation
Control Module References for scan tool information
• | Heated Seat Switch |
• | Back Only Heat Switch |
⇒ | If not the specified value, replace the appropriate door lock/window switch. |
• | Driver Seat Heat Zone |
• | Psgr. Seat Heat Zone |
⇒ | If not the specified value, replace the MSM. |
• | Driver Seat Temp. Setting |
• | Psgr. Seat Temp. Setting |
⇒ | If not the specified values, replace the MSM. |
⇒ | If any of the indicators do not illuminate, replace the appropriate door lock/window switch. |
⇒ | If the test lamp does not illuminate, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the MSM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for MSM and door lock/window switch replacement, programming, and setup |