For 1990-2009 cars

### 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 B2425 04: Left Seat Heater Cushion Circuit Open
DTC B2425 0A: Left Seat Heater Cushion Circuit Rate of Change Below Threshold
DTC B2425 0B: Left Seat Heater Cushion Circuit Current Above Threshold
DTC B2425 0C: Left Seat Heater Cushion Circuit Current Below Threshold
DTC B2425 0D: Left Seat Heater Cushion Circuit Resistance Above Threshold
DTC B2425 0E: Left Seat Heater Cushion Circuit Resistance Below Threshold
DTC B2425 1F: Left Seat Heater Cushion Circuit Intermittent
DTC B2430 04: Right Seat Heater Cushion Circuit Open
DTC B2430 0A: Right Seat Heater Cushion Circuit Rate of Change Below Threshold
DTC B2430 0B: Right Seat Heater Cushion Circuit Current Above Threshold
DTC B2430 0C: Right Seat Heater Cushion Circuit Current Below Threshold
DTC B2430 0D: Right Seat Heater Cushion Circuit Resistance Above Threshold
DTC B2430 0E: Right Seat Heater Cushion Circuit Resistance Below Threshold
DTC B2430 1F: Right Seat Heater Cushion Circuit Intermittent

### Diagnostic Fault Information

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

### Circuit/System Description

Both, the driver and passenger heated seats are controlled by the heated seat module (HSM) that is located under the driver seat cushion. When the heated seat is active, the HSM applies power through a common voltage supply circuit to the seat heater elements. The HSM controls the seat temperature by providing a pulse width modulation (PWM) ground through the seat heater element control circuit to the heater elements. The HSM then monitors the current flow through the heating elements and the rate of change of the temperature sensor to verify correct heated seat operation.

### Conditions for Running the DTC

The HSM must be powered and the heated seat must be enabled.

### Conditions for Setting the DTC

#### B2425 04 or B2430 04

The HSM does not detect a temperature change for up to 210 seconds.

#### B2425 0A or B2430 0A

The HSM detects that the set point temperature has not been reached for up to 8.5 minutes.

#### B2425 0B, B2425 0E, B2430 0B, or B2430 0E

By measuring current and voltage output to the seat heating elements every 10 seconds, the HSM calculates that the heating element resistance is below the minimum resistance.

#### B2425 0C, B2425 0D, B2430 0C, or B2430 0D

By measuring current and voltage output to the seat heating elements every 10 seconds, the HSM calculates that the heating element resistance is above the maximum resistance.

#### B2425 1F or B2430 1F

The temperature sensor voltage is erratic or changes suddenly.

### 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 clears when the malfunction is no longer present, and the power mode changes to 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

#### B2425 0A, B2425 0B, B2425 0C, B2425 0D, B2425 0E, B2425 04, or B2425 1F

1. Ignition OFF, disconnect the harness connector at the seat back heating element.

Note: When measuring resistance, all of the resistance values below are based on the seat being at room temperature of 20°C (68°F).

2. Test for 0.5 - 2.5 Ω between terminal A and terminal B.

⇒ | If not within the specified range, replace the seat back heating element.

3. Connect the harness connector at the seat back heating element.
4. Disconnect the X1 harness connector at the HSM.
5. Test for 1.5 - 5 Ω between control circuit terminal 3 and control circuit terminal 5.

⇒ | If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat cushion heating element.

⇒ | If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat cushion heating element.

6. Disconnect the X2, X4 harness connectors at the HSM.
7. Test for 1.9 k-300 kΩ between the signal circuit terminal 9 X4 and the low reference circuit terminal 6 X2.

⇒ | 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 temperature sensor.

⇒ | If greater than the specified range, test the signal circuit and the low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat temperature sensor.

8. Ignition OFF, connect the X1, X2, X4 harness connectors at the HSM.
9. Disconnect the harness connector at the seat cushion heating element/temperature sensor.
10. Ignition ON, test for 4.8 - 5.2 V between the signal circuit terminal A and ground.

⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the HSM.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.

11. If all circuits test normal, replace the HSM.

#### B2430 0A, B2430 0B, B2430 0C, B2430 0D, B2430 0E, B2430 04, or B2430 1F

1. Ignition OFF, disconnect the harness connector at the seat back heating element.

Note: When measuring resistance, all of the resistance values below are based on the seat being at room temperature of 20°C (68°F).

2. Test for 0.5 - 2.5 Ω between terminal A and terminal B.

⇒ | If not within the specified range, replace the seat back heating element.

3. Connect the harness connector at the seat back heating element.
4. Disconnect the X1 harness connector at the HSM.
5. Test for less than 1.5 - 5 Ω between control circuit terminal 6 and control circuit terminal 2.

⇒ | If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat cushion heating element.

⇒ | If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat cushion heating element.

6. Disconnect the X2, X4 harness connectors at the HSM.
7. Test for 1.9 k - 300 kΩ between the signal circuit terminal 20 X4 and the low reference circuit terminal 8 X2.

⇒ | 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 temperature sensor.

⇒ | If greater than the specified range, test the signal circuit and the low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat temperature sensor.

8. Ignition OFF, connect the X1, X2, X4 harness connectors at the HSM.
9. Disconnect the harness connector at the seat cushion heating element/temperature sensor.
10. Ignition ON, test for 4.8 - 5.2 V between the signal circuit terminal A and ground.

⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the HSM.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.

11. 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

• | Driver or Passenger Seat Cushion Heater Replacement

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