GM Service Manual Online
For 1990-2009 cars only

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 B2345 13: Front Seat Heater Temperature Above Threshold

DTC B2345 42: Front Seat Heater Current Sensing Calibration Not Present

DTC B2345 4B: Seat Heater Current Sensing Calibration data Out of Range

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 0D

B2508 01

B1935 0E

Driver Heated Seat Back Element Control

B2508 02

B1935 0D

B2508 01

B1935 0E

Driver Heated Seat Back Temperature Sensor Signal

B2435 02

B2435 05

B2435 05

B2345 13, B2345 42, B2345 4B

Driver Heated Seat Back Temperature Sensor Low Reference

--

B2435 05

--

B2345 13, B2345 42, B2345 4B

Driver Heated Seat Cushion Element Supply Voltage

B2508 02

B2425 0D

B2508 01

B2425 0E

Driver Heated Seat Cushion Element Control

B2508 02

B2425 0D

B2508 01

B2425 0E

Driver Heated Seat Cushion Temperature Sensor Signal

B1925 02

B1925 05

B1925 05

B2345 13, B2345 42, B2345 4B

Driver Heated Seat Cushion Temperature Sensor Low Reference

--

B1925 05

--

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Back Element Supply Voltage

B2508 02

B2180 0D

B2508 01

B2180 0E

Passenger Heated Seat Back Element Control

B2508 02

B2180 0D

B2508 01

B2180 0E

Passenger Heated Seat Back Temperature Sensor Signal

B2440 02

B2440 05

B2440 05

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Back Temperature Sensor Low Reference

--

B2440 05

--

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Cushion Element Supply Voltage

B2508 02

B2430 0D

B2508 01

B2430 0E

Passenger Heated Seat Cushion Element Control

B2508 02

B2430 0D

B2508 01

B2430 0E

Passenger Heated Seat Cushion Temperature Sensor Signal

B2170 02

B2170 05

B2170 05

B2345 13, B2345 42, B2345 4B

Passenger Heated Seat Cushion Temperature Sensor Low Reference

--

B2170 05

--

B2345 13, B2345 42, B2345 4B

Circuit/System Description

The driver and passenger heated seat heating elements are controlled by a common high current relay internal to the memory seat module (MSM) and the low side by individual element control circuits. The MSM connects the heated seat heater element supply voltage circuits for both seats to a common reference point. This reference point is biased to approximately 2.0 volts. Before the MSM will allow heated seat operation, it checks to see if this reference voltage is shorted to ground or battery voltage. Once the module verifies that it is not closing to a shorted heating element, it allows heated seat operation. After which it continues to monitor for a shorted circuit.

Conditions for Running the DTC

The MSM must be powered.

Conditions for Setting the DTC

B2345 13

Any temperature sensor input that remains below 1.5 volts for more than 1 second.

B2345 42

This DTC will set if the module calibration data set is not present.

B2345 4B

This DTC will set if the module calibration is out of range.

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 the code to history 3 seconds after the reference voltage returns to the 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

B2345 13

  1. Ignition OFF, disconnect the X2, X5 harness connectors at the MSM.
  2. Test for greater than 3.0K ohms between the signal circuit and the low reference circuits listed below:
  3. • Driver seat cushion terminal 1 X5 and terminal 3 X2
    • Passenger seat cushion terminal 2 X5 and terminal 6 X2
    If less than the specified value, test for a short between the signal and low reference circuits. If the circuits test normal, replace the appropriate seat cushion temperature sensor.
  4. Test for greater than 2.4K ohms between the signal circuit and the low reference circuits listed below:
  5. • Driver seat back terminal 4 X5 and terminal 2 X2
    • Passenger seat back terminal 3 X5 and terminal 5 X2
    If less than the specified value, test for a short between the signal and low reference circuits. If the circuits test normal, replace the appropriate seat back temperature sensor.
  6. If all circuits test normal, replace the MSM.

B2345 42 or B2345 4B

If either DTC is set, replace the MSM.

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 MSM replacement, setup and programming