Without Memory A45
DTC B2435 or B2440 (Without Memory A45)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B2435 02
-
Left Seat Back Heater Sensor Circuit Short to Ground
DTC B2435 05
-
Left Seat Back Heater Sensor Circuit Short to Battery or Open
DTC B2440 02
-
Right Seat Back Heater Sensor Circuit Short to Ground
DTC B2440 05
-
Right Seat Back Heater Sensor Circuit Short to Battery or Open
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 heated seat module (HSM) supplies a 5-volt reference voltage through the temperature sensor signal circuit and a ground through the low reference circuit to the sensor. The module monitors the voltage of the sensor signal circuit 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 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 sensor.
Conditions for Running the DTC
The HSM must be powered.
Conditions for Setting the DTC
B2435 02 and B2440 02
The temperature sensor voltage is less than 0.80 volts for more than 1 second.
B2435 05 and B2440 05
The temperature sensor voltage is greater than 5 volts for more than 1 second.
Action Taken When the DTC Sets
The heated seat function for the affected seat will be disabled.
Conditions for Clearing the DTC
* The current DTC will clear and set the code to history 3 seconds after the reference voltage returns to normal operating range and the ignition is cycled OFF then back to ACC or RUN.
* The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics (Except A45) Heated/Cooled Seat SchematicsHeated/Cooled Seat Schematics (With KA1) Heated/Cooled Seat Schematics (With KA1)Heated/Cooled Seat Schematics (With KB6) Heated/Cooled Seat Schematics (With KB6)
Connector End View Reference
Component Connector End Views A/C Compressor Clutch
Description and Operation
Heated Seats Description and Operation Heated Seats
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Testing
B2435 02 or B2435 05
1. Ignition OFF, disconnect the X2, X4 harness connectors at the HSM.
Important:
When measuring the resistance, the resistance values are based on the seat being at room temperature of 20°C (68°F).
2. Test for 3.3K-300K ohms between the signal circuit terminal 19 X4 and the low reference circuit terminal 5 X2.
• If greater than the specified range, test the signal circuit and low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back temperature sensor.
• If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back temperature sensor.
3. Ignition OFF, connect the X2, X4 harness connectors at the HSM.
4. Disconnect the harness connector at the seat back heating element/temperature sensor.
5. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the HSM.
6. If all circuits test normal, replace the HSM.
B2440 02 or B2440 05
1. Ignition OFF, disconnect the X2, X4 harness connectors at the HSM.
Important:
When measuring the resistance, the resistance values are based on the seat being at room temperature of 20°C (68°F).
2. Test for 3.3K-300K ohms between the signal circuit terminal 10 X4 and the low reference circuit terminal 7 X2.
• If greater than the specified range, test the signal circuit and low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back temperature sensor.
• If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back temperature sensor.
3. Ignition OFF, connect the X2, X4 harness connectors at the HSM.
4. Disconnect the harness connector at the seat cushion heating element/temperature sensor.
5. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the HSM.
6. If all circuits test normal, replace the HSM.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Driver or Passenger Seat Back Cushion Heater Replacement Driver or Passenger Seat Back Cushion Heater Replacement
* Control Module References Programming and Relearning for HSM replacement, setup, and programming