Chevrolet Silverado / GMC Sierra. Service manual — part 2696

setup

SYMPTOMS - POWER SEATS

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in

order to verify that all of the following are true:

There are no DTCs set.

The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions.

Refer to the following system descriptions:

Memory Seats Description and Operation

Power Seats System Description and Operation

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the system. Refer to
Checking Aftermarket Accessories .

Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:

Memory Seat Feature Inoperative

Power Seat Inoperative (w/o Memory) or Power Seat Inoperative (w/Memory)

MEMORY SEAT FEATURE INOPERATIVE

Diagnostic Instructions

IMPORTANT: The following steps must be completed before using the symptom

tables.

2008 Chevrolet Silverado 1500

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

Silverado

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.

Diagnostic Fault Information

Circuit/System Description

Battery positive voltage is supplied to the memory function switch from the driver door switch
(DDS). When a memory switch is pressed, battery voltage is applied through the switch contacts,
a series of resistors, and thorough the memory switch signal circuit to the DDS. The door control
module then sends a message via the GMLAN serial data line to the memory seat module (MSM)
indicating the memory recall request. The MSM then commands the appropriate seat motors to
move to the pre-recorded seat positions stored in memory in response to the switch input.

Reference Information

Schematic Reference

Driver Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Memory Seats Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Memory Switch Signal

1

1

1

-

Memory Switch Supply
Voltage

-

1

-

-

1. Memory Seat Feature Inoperative

2008 Chevrolet Silverado 1500

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

Silverado

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify that all manual power seat and lumbar functions operate as described in the

description and operation.

2. Verify that memory positions for driver 1 and driver 2 have been recorded to memory, by

observing the scan tool Driver Position Module, Memory Data 1 and Memory Data 2
parameters.

Circuit/System Testing

1. Ignition ON, verify the scan tool Memory Recall Switches parameter is approximately 2.74

volts while pressing the memory 1 switch.

If the parameter is not the specified value, refer to Memory Switch component test
below. If the switch tests normal, replace the driver door switch.

2. Verify the scan tool Memory Recall Switches parameter is approximately 1.78 volts while

pressing the memory 2 switch.

If the parameter is not the specified value, replace the memory switch.

3. Verify the scan tool Memory Recall Switches parameter is approximately 0.96 volt while

pressing the EXIT switch.

If the parameter is not the specified value, replace the memory switch.

4. If all circuits test normal, replace the memory seat module.

Component Testing

Memory Switch

1. Disconnect the X4 harness connector at driver door switch.

2. Test for infinite resistance between the memory switch signal circuit terminal 5 and the

switch supply voltage circuit terminal 14.

If not infinite, replace the memory switch.

3. Test the resistance between terminal 14 and terminal 5 while pressing the memory 1,

memory 2, and EXIT buttons. Compare the resistance readings to the values in the Memory

2008 Chevrolet Silverado 1500

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

Silverado

Switch Values table below.

If the resistance is not within the specified range, replace the memory switch.

Memory Switch Values

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Driver Seat Adjuster Memory Switch Replacement (Crew Cab)

Control Module References for MSM of DDS replacement, programming, and setup

POWER SEAT INOPERATIVE (W/O MEMORY)

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

Diagnostic Fault Information

Switch Position

Resistance

Idle

Infinite

Memory 1

2.03K-2.49K ohms

Memory 2

3.83K-4.69K ohms

Exit

9.32K-10.18K ohms

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Lumbar Switch B+

1, 2

2

-

-

Power Seat Switch B+

1, 2

1

-

-

Front Vertical Motor Front
Down Control

1

1

-

-

Front Vertical Motor Front Up
Control

1

1

-

-

Horizontal Motor Forward
Control

1

1

-

-

Horizontal Motor Rearward
Control

1

1

-

-

2008 Chevrolet Silverado 1500

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

Silverado