Content .. 2753 2754 2755 2756 ..
Chevrolet Silverado / GMC Sierra. Manual - part 2755
DTC B2435 OR B2440
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 B2435 02
Left Seat Back Heater Sensor Circuit Shorted to Ground
DTC B2435 05
Left Seat Back Heater Sensor Circuit Shorted to Battery or Open
DTC B2440 02
Right Seat Back Heater Sensor Circuit Shorted to Ground
DTC B2440 05
Right Seat Back Heater Sensor Circuit Shorted to Battery or Open
Diagnostic Fault Information
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 Back
Element Control
B2508 02
B1935 0C
B1935 0D
B2508 01
-
Left Heated Seat Back
Temperature Sensor Signal
B2435 02
B1935 04
B1935 1F
B2435 05
B1935 04
B1935 1F
B2435 05
-
Left Heated Seat Back
Temperature Low Reference
-
B1935 04
B1935 1F
B2435 05
-
-
Right Heated Seat Back
B2180 0C
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Circuit/System Description
The heated seat temperature sensor is located in the seat back just under the seat cover with the
seat heating element. The temperature sensor is a 2 wire thermistor and resistance through the
sensor varies with temperature. The signal circuit is referenced from 5 volts within the module
and the temperature of the seat surface determines the signal circuit voltage. Once the seat reaches
the set temperature, the module will then cycle the control circuits of the heating elements ON
and OFF in order to maintain the desired seat temperature based on the feedback voltage from the
sensors.
Conditions for Running the DTC
The heated seat system must be active.
Conditions for Setting the DTC
B2435 02, B2440 02
The temperature sensor voltage drops below 0.8 volt for more than 1 second.
B2435 05, B2440 05
The temperature sensor voltage is greater than 5 volts for more than 1 second.
Action Taken When the DTC Sets
The heated seat back function for the affected seat will be disabled.
Conditions for Clearing the DTC
The current DTC will clear 3 seconds after the reference voltage returns to normal operating
range, and the ignition is cycled OFF then back to ACC or RUN.
Element Supply Voltage
B2508 02
B2180 0D
B2508 01
-
Right Heated Seat Back
Element Control
B2508 02
B2180 0C
B2180 0D
B2508 01
-
Right Heated Seat Back
Temperature Sensor Signal
B2440 02
B2180 04
B2180 1F
B2440 05
B2180 04
B2180 1F
B2440 05
-
Right Heated Seat Back
Temperature Low Reference
-
B2180 04
B2180 1F
B2440 05
-
-
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
A history DTC will clear after 50 ignition cycles or with a scan tool using the clear DTCs
function.
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
B2435
1. Ignition OFF, disconnect the X2, X5 harness connectors at the MSM.
2. Test for 850-300k ohms between the 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 circuit tests normal, replace the seat
back 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 back heater element.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
3. Connect the X2, X5 harness connectors at the MSM.
4. Disconnect the harness connector at the seat back 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.
B2440
1. Ignition OFF, disconnect the X2, X5 harness connectors at the MSM.
2. Test for 850-300k ohms between the 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 circuit tests normal, replace the seat
back 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 back heater element.
3. Connect the X2, X5 harness connectors at the MSM.
4. Disconnect the harness connector at the seat back 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 Back Cushion Heater Replacement
Control Module References for the MSM replacement, setup, and programming
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Seat Heating and Cooling - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Content .. 2753 2754 2755 2756 ..