Chevrolet Silverado / GMC Sierra. Manual — part 2751

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.

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

B2170

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

2. Test for 850-300k ohms between the signal circuit terminal 2 X5 and the low reference

circuit terminal 6 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 circuit tests normal, replace the seat
cushion heater element.

If less than the specified range, test for a short between the signal and low reference
circuits. If the circuit tests normal, replace the seat cushion heater element.

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

4. Disconnect the harness connector at the seat cushion heater element.

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

6. 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 Cushion Heater Replacement

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

DTC B1935 OR B2180

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

2008 Chevrolet Silverado 1500

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

Sierra & Silverado

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1935 04

Left Seat Back Heater Circuit Open

DTC B1935 0A

Left Seat Back Heater Circuit Rate of Change Below Threshold

DTC B1935 0B

Left Seat Back Heater Circuit Current Above Threshold

DTC B1935 0C

Left Seat Back Heater Circuit Current Below Threshold

DTC B1935 0D

Left Seat Back Heater Circuit Resistance Above Threshold

DTC B1935 0E

Left Seat Back Heater Circuit Resistance Below Threshold

DTC B1935 1F

Left Seat Back Heater Circuit Intermittent

DTC B2180 04

Right Seat Back Heater Circuit Open

DTC B2180 0A

Right Seat Back Heater Circuit Rate of Change Below Threshold

DTC B2180 0B

2008 Chevrolet Silverado 1500

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

Sierra & Silverado

Right Seat Back Heater Circuit Current Above Threshold

DTC B2180 0C

Right Seat Back Heater Circuit Current Below Threshold

DTC B2180 0D

Right Seat Back Heater Circuit Resistance Above Threshold

DTC B2180 0E

Right Seat Back Heater Circuit Resistance Below Threshold

DTC B2180 1F

Right Seat Back Heater Circuit Intermittent

Diagnostic Fault Information

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Left Heated Seat Cushion
Element Supply Voltage

B2508 02

B2425 0C

B2425 0D

B2508 01

-

Left Heated Seat Cushion
Element Control

B2508 02

B2425 0C

B2425 0D

B2508 01

-

Left Heated Seat Cushion
Temperature Sensor Signal

B1925 02

B1925 05
B2425 04

B2425 1F

B1925 05
B2425 04

B2425 1F

-

Left Heated Seat Cushion
Temperature Low Reference

-

B1925 05
B2425 04

B2425 1F

-

-

Right Heated Seat Cushion
Element Supply Voltage

B2508 02

B2430 0C

B2430 0D

B2508 01

-

Right Heated Seat Cushion
Element Control

B2508 02

B2430 0C

B2430 0D

B2508 01

-

Right Heated Seat Cushion
Temperature Sensor Signal

B2170 02

B2170 05
B2430 04

B2430 1F

B2170 05
B2430 04

B2430 1F

-

B2170 05

2008 Chevrolet Silverado 1500

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

Sierra & Silverado

Circuit/System Description

When the heated seat function is active, the Memory Seat Module (MSM) supplies battery
voltage through the element supply voltage circuit to the seat heater elements. The module
controls the seat temperature by providing a PWM ground through the heated seat element
control circuit to the seat heater elements. The module then monitors the current flow through the
heating element and the temperature sensor rate of change to verify correct operation.

Conditions for Running the DTC

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

Conditions for Setting the DTC

B1935 04, B2180 04

The module does not detect a temperature change within 210 seconds.

B1935 0A, B2180 0A

The module detects that the set point temperature has not been reached within 8.5 minutes.

B1935 0B, B1935 0E, B2180 0B, B2180 0E

By measuring output current, the module calculates that the heating element resistance is below
the minimum resistance.

B1935 0C, B1935 0D, B2180 0C, B2180 0D

By measuring output current, the module calculates that the heating element resistance is above
the maximum resistance.

B1935 1F, B2180 1F

The temperature sensor voltage is erratic or changes suddenly.

Action Taken When the DTC Sets

The heated seat back function for the affected seat will be disabled.

Conditions for Clearing the DTC

Right Heated Seat Cushion
Temperature Low Reference

-

B2430 04

B2430 1F

-

-

2008 Chevrolet Silverado 1500

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

Sierra & Silverado