B2435

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 Descriptor

DTC B2435
- Driver Seat Back Heater Sensor Circuit

DTC B2440
- Passenger Seat Back Heater Sensor Circuit

Diagnostic Fault Information






Circuit/System Description

The memory seat module (MSM) relies on inputs from thermistors located in the driver and passenger seat backs to control heated seat temperatures. The thermistors are 2 wire sensors supplied with a 5-volt referenced signal circuit and low reference circuit from the MSM. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the seat back temperatures rise.

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 volts 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.
* A history DTC will clear after 100 consecutive ignition cycles without a fault present.

Circuit/System Verification

1. Ignition ON, observe the scan tool Seat Heat Sensor parameter. The reading should be between 4.94 and 0.07 volts and change from high to low as the seat heats.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the seat back heater element.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal D and ground.

^ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the MSM.

3. Ignition ON, verify the scan tool Seat Heat Sensor parameter is greater than 4.94 volts.

^ 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.

4. 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 0.07 volts.

^ 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.

5. If all circuits test normal, test or replace the seat back heater element.

Repair Instructions

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