B2440

DTC B2435 or B2440

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 02
- Left Seat Back Heater Sensor Circuit Shorted to Ground

DTC B2440 02
- Right Seat Back Heater Sensor Circuit Shorted to Ground

Diagnostic Fault Information






Circuit/System Description

The heated seat temperature sensor that set this diagnostic trouble code (DTC) is located in the seat back just under the seat cover with the seat heating element. The temperature sensor is a 2 wire thermistor and resistance through the sensor varies with temperature. The signal circuit is referenced from 5 volts within the module and the temperature of the seat surface determines the signal circuit voltage. Once the seat reaches the set temperature, the module will then 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 memory seat module (MSM) must be powered.

Conditions for Setting the DTC

The temperature sensor voltage drops below 0.8 volt for more than 1 second.

Action Taken When the DTC Sets

The heated seat back function for the affected seat will be disabled.

Conditions for Clearing the DTC

* The current DTC will clear 3 seconds after the reference voltage returns to normal operating range, and the ignition is cycled OFF then back to ACC or RUN.
* A history DTC will clear after 50 ignition cycles or with a scan tool using the clear DTCs function.

Circuit/System Testing

1. Ignition OFF, disconnect the MSM harness connector X5.
2. Test for a minimum of 850 ohms of resistance from the signal circuit to ground.

^ If less than 850 ohms, test the signal circuit for a short to ground. If the circuit tests normal, replace the seat back heater element.

3. If all circuits test normal, replace the MSM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Driver Seat Back Cushion Heater and Passenger Seat Back Cushion Heater Replacement (with HP2) Driver Seat Back Cushion Heater and Passenger Seat Back Cushion Heater Replacement (without HP2)