Heated Seats Description and Operation

[Rusty2009]

DTC B242A

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 B242A 01: Seat Heaters Common Circuit Short to Battery

DTC B242A 02: Seat Heaters Common Circuit Short to Ground

Diagnostic Fault Information

[TR] [TD]Circuit[/TD] [TD]Short to Ground[/TD] [TD]Open/High Resistance[/TD] [TD]Short to Voltage[/TD] [TD]Signal Performance[/TD] [/TR] [TR] [TD]Driver Heated Seat Element Control Terminal 3 X2[/TD] [TD]B242A 02[/TD] [TD]B2425 0D[/TD] [TD]B242A 01[/TD] [TD]B2425 0E[/TD] [/TR] [TR] [TD]Driver Heated Seat Element Control Terminal 1 X2[/TD] [TD]B242A 02[/TD] [TD]B2425 0D[/TD] [TD]B242A 01[/TD] [TD]B2425 0E[/TD] [/TR] [TR] [TD]Driver Heated Seat Cushion Temperature Sensor Signal[/TD] [TD]B1925 02[/TD] [TD]B1925 05[/TD] [TD]B1925 05[/TD] [TD]B2345 13[/TD] [/TR] [TR] [TD]Driver Heated Seat Cushion Temperature Sensor Low Reference[/TD] [TD]--[/TD] [TD]B1925 05[/TD] [TD]--[/TD] [TD]B2345 13[/TD] [/TR] [TR] [TD]Passenger Heated Seat Element Control Terminal 5 X2[/TD] [TD]B242A 02[/TD] [TD]B2430 0D[/TD] [TD]B242A 01[/TD] [TD]B2430 0E[/TD] [/TR] [TR] [TD]Passenger Heated Seat Element Control Terminal 2 X2[/TD] [TD]B242A 02[/TD] [TD]B2430 0D[/TD] [TD]B242A 01[/TD] [TD]B2430 0E[/TD] [/TR] [TR] [TD]Passenger Heated Seat Cushion Temperature Sensor Signal[/TD] [TD]B2170 02[/TD] [TD]B2170 05[/TD] [TD]B2170 05[/TD] [TD]B2345 13[/TD] [/TR] [TR] [TD]Passenger Heated Seat Cushion Temperature Sensor Low Reference[/TD] [TD]--[/TD] [TD]B2170 05[/TD] [TD]--[/TD] [TD]B2345 13[/TD] [/TR]

Circuit/System Description

The seat heating control module controls the seat heating operation for both the driver and front passenger seats. The module controls the heating elements through individual high side and low side control circuits. The low side control circuits for both seats are connected to a common reference point internal to the module. This reference point is biased to approximately 2.5 V. Before the seat heating control module will allow heated seat operation, it checks to see if this biased voltage is shorted to ground or voltage. Once the module verifies that it is not closing to a shorted heating element, it allows for heated seat operation. The module will then continue to monitor the heating elements for a shorted circuit.

Conditions for Running the DTC

• DTC B1325 must not be present.
• The seat heating control module must be powered.

Conditions for Setting the DTC

B242A 01

The seat heating control module detects a short to voltage on the heater element control circuits.

B242A 02

The seat heating control module detects a short to ground on the heater element control circuits.

Action Taken When the DTC Sets

The heated seat function for both seats will be disabled.

Conditions for Clearing the DTC

• The current DTC will clear and set a history code 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 40 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



1. Ignition OFF, disconnect the X2 harness connector at the K29 seat heating control module.

2.Test for infinite resistance between the control circuit terminal 3 and ground.
⇒ If not the specified value, test the control circuit for a short to ground.

3. Test for infinite resistance between the control circuit terminal 5 and ground.
⇒ If not the specified value, test the control circuit for a short to ground.

4. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 3 and ground.
⇒ If the test lamp illuminates, test the control circuit for a short to voltage.

5. Verify that a test lamp does not illuminate between the control circuit terminal 5 and ground.
⇒ If the test lamp illuminates, test the control circuit for a short to voltage.

6. If all circuits test normal, replace the K29 seat heating control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for seat heating control module replacement, setup, and programming