Chevrolet Silverado / GMC Sierra. Service manual - part 2691

Circuit/System Description

The memory seat module (MSM) monitors the current supplied to the seat adjuster motors. The
MSM can detect both absolute and differential current levels from the seat motors. Absolute
current is the maximum allowable current the module will supply to the motors. A differential
current mismatch occurs when the current supplied to the seat motors does not match the current
returning from the motors.

Conditions for Running the DTC

The MSM establishes that it is not closing to a shorted motor control circuit before the motors are
active.

Conditions for Setting the DTC

The following conditions exist for more than 1 second:

B1335 00

Current out of the module does not match the current returning to the module within 5 amps.

B1335 0B

The absolute current or an over-current has exceeded the maximum value allowed.

B1335 42

This DTC will set if the module calibration is not programmed.

B1335 4B

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

Action Taken When the DTC Sets

The adjustable pedal motor and all driver seat adjuster motors are disabled.

Rearward Control

B3920 02

B3920 01

B1335 0B

Adjustable Pedal Motor
Forward Control

B3920 02

B3920 01

B1335 00

B1335 0B

Adjustable Pedal Motor
Rearward Control

B3920 02

B3920 01

B1335 00

B1335 0B

1. Power seat motor inoperative

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Conditions for Clearing the DTC

The current DTC will clear and set the code to history, 3 seconds after no motor movement
is requested or the current is no longer mismatched, and the ignition is cycled OFF then
back to ACC or RUN.

A history DTC will clear after 50 ignition cycles or with a scan tool using the clear DTCs
function.

Reference Information

Schematic Reference

Driver Seat Schematics

Passenger Seat Schematics

Adjustable Pedal Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Memory 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

Module Internal Malfunction

If DTCs B1335 42 or B1335 4B are set history or current, the only option is module replacement.

Circuit/System Testing

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

1. Use a scan tool to clear the current and history diagnostic trouble code.

2. Ignition ON, while observing the scan tool for DTCs, operate the seat adjuster switch in

both directions for each directional motor.

3. Disconnect the suspect seat motor for which the DTC set.

4. Clear the current and history diagnostic trouble code.

5. While observing the scan tool for DTCs, operate the suspect seat motor adjuster switch in

both directions.

If the DTC set current or history, test the motor control circuits for a short to ground,
or an open/high resistance. If the circuits test normal, replace the memory seat module.

6. If all circuits/connections test normal, replace the seat motor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Front Seat Recliner Actuator Motor Replacement

Front Seat Lumbar Support Replacement

Front Seat Adjuster Replacement (Power)

Brake Pedal Assembly Replacement

Control Module References for MSM replacement, setup, and programming

DTC B1395

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 B1395 02

Device Voltage Reference Output Circuit Shorted to Ground

DTC B1395 05

Device Voltage Reference Output Circuit Shorted to Battery or Open

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Diagnostic Fault Information

Circuit/System Description

The memory seat module (MSM) supplies a 5-volt reference voltage to the driver seat and
adjustable pedal position sensors. The MSM monitors this reference voltage to ensure the
accuracy of the voltages being returned from the sensors. If the voltage exceeds the normal
operating range, errors will occur in the memory recall operations of the seat and adjustable
pedals.

Conditions for Running the DTC

The memory seat module must be powered.

Conditions for Setting the DTC

The following conditions exist for more than 1 second:

B1395 02

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

5-Volt Reference

B1395 02

B1395 05

Memory Seat Sensor Low
Reference

B1825 01,
B1850 01,
B1860 01,
B2355 01,
B2365 01,

B2375 01

Driver Seat Front Vertical
Position Sensor Signal

B2355 06

B2355 01

Driver Seat Rear Vertical
Position Sensor Signal

B2365 06

B2365 01

Driver Seat Horizontal Position
Sensor Signal

B2375 06

B2375 01

Driver Seat Lumbar Vertical
Position Sensor Signal

B1860 06

B1860 01

Driver Seat Lumbar Horizontal
Position Sensor Signal

B1850 06

B1850 01

Driver Seat Recline Position
Sensor Signal

B1825 06

B1825 01

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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