For 1990-2009 cars

## DTC B2435 or B2440 With Memory A45

### 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 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
B+ MSM Terminal 5 X3 | 1, 2, B1935 0C, B1935 0D, B2180 0C, B2180 0D, B2425 0C, B2425 0D, B2430 0C, B2430 0D | 1, 2, B1935 0C, B1935 0D, B2180 0C, B2180 0D, B2425 0C, B2425 0D, B2430 0C, B2430 0D | -- | --
Driver Heated Seat Back Element Supply Voltage | B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E
Driver Heated Seat Back Element Control | B2345 00, B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E
Driver Heated Seat Back Temperature Sensor Signal | B2435 02 | B1935 04, B1935 1F, B2435 0D | B1935 04, B1935 1F, B2435 0D | B1935 0A, B2345 13, B2345 42, B2345 4B
Driver Heated Seat Back Temperature Sensor Low Reference | -- | B1935 04, B1935 1F, B2435 0D | -- | B2345 13, B2345 42, B2345 4B
Driver Heated Seat Cushion Element Supply Voltage | B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E
Driver Heated Seat Cushion Element Control | B2345 00, B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E
Driver Heated Seat Cushion Temperature Sensor Signal | B1925 02, B2425 1F | B1925 05, B2425 04, B2425 1F | B1925 05, B2425 04, B2425 1F | B2345 13, B2345 42, B2345 4B, B2425 0A
Driver Heated Seat Cushion Temperature Sensor Low Reference | -- | B1925 05, B2425 04, B2425 1F | -- | B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Back Element Supply Voltage | B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E
Passenger Heated Seat Back Element Control | B2345 00, B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E
Passenger Heated Seat Back Temperature Sensor Signal | B2440 02 | B2180 04, B2180 1F, B2440 05 | B2180 04, B2180 1F, B2440 05 | B2180 0A, B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Back Temperature Sensor Low Reference | -- | B2180 04, B2180 1F, B2440 05 | -- | B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Cushion Element Supply Voltage | B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E
Passenger Heated Seat Cushion Element Control | B2345 00, B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E
Passenger Heated Seat Cushion Temperature Sensor Signal | B2170 02, B2430 1F | B2430 04, B2430 1F, B2170 05 | B2430 04, B2430 1F, B2170 05 | B2345 13, B2345 42, B2345 4B, B2430 0A
Passenger Heated Seat Cushion Temperature Sensor Low Reference | -- | B2430 04, B2430 1F, B2170 05 | -- | B2345 13, B2345 42, B2345 4B
1. Power seat inoperative 2. 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 heated seat system must be active.

### 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 appropriate 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.

### Reference Information

#### Schematic Reference

Heated/Cooled Seat Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Heated Seats Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

#### B2435 02 or B2435 05

1. Ignition OFF, disconnect the X2, X5 harness connectors at the MSM.

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 4 X5 and the low reference circuit terminal 2 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, X5 harness connectors to the MSM.
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 temperature sensor 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 MSM.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

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

#### B2440 02 or B2440 05

1. Ignition OFF, disconnect the X2, X5 harness connectors at the MSM.

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 3 X5 and the low reference circuit terminal 5 X2.

⇒ | If greater than the specified range, test the signal and low reference circuits 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, X5 harness connectors to the MSM.
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 temperature sensor 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 MSM.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Driver or Passenger Seat Back Cushion Heater Replacement

• | Control Module References for MSM replacement, setup, and programming

## DTC B2435 or B2440 Without Memory A45

### 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 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Driver Heated Seat Back Element Supply Voltage | B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E
Driver Heated Seat Back Element Supply Control | B2345 00, B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E
Driver Heated Seat Back Temperature Sensor Signal | B2435 02 | B1935 04, B1935 1F, B2435 0D | B1935 04, B1935 1F, B2435 0D | B1935 0A, B2345 13, B2345 42, B2345 4B
Driver Heated Seat Back Temperature Sensor Low Reference | -- | B1935 04, B1935 1F, B2435 0D | -- | B2345 13, B2345 42, B2345 4B
Driver Heated Seat Cushion Element Supply Voltage | B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E
Driver Heated Seat Cushion Element Control | B2345 00, B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E
Driver Heated Seat Cushion Temperature Sensor Signal | B1925 02, B2425 1F | B1925 05, B2425 04, B2425 1F | B1925 05, B2425 04, B2425 1F | B2345 13, B2345 42, B2345 4B, B2425 0A
Driver Heated Seat Cushion Temperature Sensor Low Reference | -- | B1925 05, B2425 04, B2425 1F | -- | B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Back Element Supply Voltage | B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E
Passenger Heated Seat Back Element Control | B2345 00, B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E
Passenger Heated Seat Back Temperature Sensor Signal | B2440 02 | B2180 04, B2180 1F, B2440 05 | B2180 04, B2180 1F, B2440 05 | B2180 0A, B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Back Temperature Sensor Low Reference | -- | B2180 04, B2180 1F, B2440 05 | -- | B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Cushion Element Supply Voltage | B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E
Passenger Heated Seat Cushion Element Control | B2345 00, B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E
Passenger Heated Seat Cushion Temperature Sensor Signal | B2170 02, B2430 1F | B2430 04, B2430 1F, B2170 05 | B2430 04, B2430 1F, B2170 05 | B2345 13, B2345 42, B2345 4B, B2430 0A
Passenger Heated Seat Cushion Temperature Sensor Low Reference | -- | B2430 04, B2430 1F, B2170 05 | -- | B2345 13, B2345 42, B2345 4B

### 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

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Heated Seats Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References 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 after completing the diagnostic procedure.

• | Driver or Passenger Seat Back Cushion Heater Replacement

• | Control Module References for HSM replacement, setup, and programming