Chevrolet Silverado / GMC Sierra. Service manual — part 2752

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

B1935

1. Ignition OFF, disconnect the X1 harness connector at the MSM.

2. Test for less than 15 ohms between the heater element supply voltage circuit terminal 14 and

the control circuit terminal 1.

If greater than the specified range, test the supply voltage circuit and the control circuit
for an open/high resistance. If the circuits test normal, replace the seat back heating
element.

3. Disconnect the X2, X5 harness connectors at the MSM.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

4. Test for 850-300k ohms between the temperature sensor 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 heating element.

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 heater element.

5. Connect the X1, X2, X5 harness connectors at the MSM.

6. Disconnect the harness connector at the seat back heater element.

7. 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 voltage. If the
circuit tests normal, replace the MSM.

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

B2180

1. Ignition OFF, disconnect the X1 harness connector at the MSM.

2. Test for less than 15 ohms between the heater element supply voltage circuit terminal 6 and

the control circuit terminal 4.

If greater than the specified range, test the supply voltage circuit and the control circuit
for an open/high resistance. If the circuits test normal, replace the seat back heating
element.

3. Disconnect the X2, X5 harness connectors at the MSM.

4. Test for 850-300k ohms between the temperature sensor signal circuit terminal 3 X5 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 heating element.

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 heating element.

5. Connect the X1, X2, X5 harness connectors at the MSM.

6. Disconnect the harness connector at the seat back heating element.

7. Ignition ON, test for 4.8-5.2 volts between the temperature sensor signal circuit terminal C

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

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 voltage. If the
circuit tests normal, replace the MSM.

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

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Driver Seat and Passenger Seat Back Cushion Heater Replacement

Control Module References for the MSM replacement, setup, and programming

DTC B2345

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 Descriptor

DTC B2345 00

Seat Heater Disable Circuit

DTC B2345 13

Seat Heater Disable Circuit High Temperature

DTC B2345 42

Seat Heater Disable Circuit Calibration Data Set Not Programmed

DTC B2345 4B

Seat Heater Disable Circuit Calibration Not Learned

Diagnostic Fault Information

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Circuit/System Description

The front seat heating elements are controlled by a common high current relay internal to the
Memory Seat Module (MSM) and on the low side by individual element control circuits. The
module connects the heated seat heater element supply voltage circuits to a common reference
point. This reference point is biased to approximately 2.0 volts. Before the module will allow
heated seat operation, it checks to see if the heating element supply voltage circuits and control
circuits are shorted to ground or battery voltage. Once the module verifies that it is not closing
into 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 00

After a heated seat is activated, the MSM detects a shorted circuit on the seat heating element
supply voltage circuit or control circuit.

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Left Heated Seat Back
Element Supply Voltage

B2508 02

B1935 0C

B1935 0D

B2508 01

-

Left Heated Seat Cushion
Element Supply Voltage

B2508 02

B2425 0C

B2425 0D

B2508 01

-

Left Heated Seat Back
Element Control

B2508 02

B1935 0C
B1935 0D

B2508 01

-

Left Heated Seat Cushion
Element Control

B2508 02

B2425 0C

B2425 0D

B2508 01

-

Right Heated Seat Back
Element Supply Voltage

B2508 02

B2180 0C

B2180 0D

B2508 01

-

Right Heated Seat Cushion
Element Supply Voltage

B2508 02

B2430 0C

B2430 0D

B2508 01

-

Right Heated Seat Back
Element Control

B2508 02

B2180 0C
B2180 0D

B2508 01

-

Right Heated Seat Cushion
Element Control

B2508 02

B2430 0C
B2430 0D

B2508 01

-

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado