Diagnostic Instructions
| • | 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. |
DTC Descriptors
DTC B2435: Driver Seat Back Heater Sensor CircuitDTC B2440: Passenger Seat Back Heater Sensor Circuit
Diagnostic Fault Information
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. | ||||
Circuit/System Description
The heated seat temperature sensor that set this DTC is located in seat back just under the seat cover with the seat heating element. The memory seat module (MSM) supplies a separate 5-volt reference voltage through the temperature sensor signal circuit and a ground through the low reference circuit to the sensor. The MSM monitors the voltage of the sensor signal circuits to determine the temperature of the seat. The temperature sensor varies in resistance based on the temperature of the heating element, causing the signal voltage to change. Once the seat reaches the set temperature, the MSM will cycle the control circuits of the heating elements ON and OFF in order to maintain the desired seat temperature based on the feedback voltage from the sensors.
Conditions for Running the DTC
The battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
| • | The heated seat sensor signal circuit voltage to the seat module is greater than 4.94 volts for 30 seconds or more. |
| • | The heated seat sensor signal circuit voltage to the seat module is less than 0.07 volt for 30 seconds or more. |
| • | The heated seat sensor signal circuit input to the seat module indicates that the desired seat temperature has not been reached within 34 minutes after activation. |
Action Taken When the DTC Sets
The heated seat with a current status DTC will be disabled.
Conditions for Clearing the DTC
| • | This DTC will clear on current status after the condition for setting the fault is corrected. |
| • | The history DTC will clear after 100 consecutive fault-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Heated Seats Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool heated seat sensor parameters listed below. The readings should be between 4.94 and 0.07 volts and change from high to low as the seat gets warm.
| • | Drvr. Seat Heat Sensor |
| • | Psgr. Seat Heat Sensor |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate seat back heater element.
- Test for less than 5.0 ohms between the low reference circuit terminal D and ground.
- Ignition ON, verify the appropriate scan tool Seat Heat Sensor parameter is greater than 4.5 volts.
- Install a 3A fused jumper wire between the signal circuit terminal C and the low reference circuit terminal D. Verify the scan tool Seat Heat Sensor parameter is less than 0.5 volts.
- If all circuits test normal, test or replace the seat back heater element.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the MSM. |
| ⇒ | If less than the specified range, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the MSM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the MSM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for MSM replacement, programming, and setup |
