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Chevrolet Silverado / GMC Sierra. Manual - part 2697
Circuit/System Description
Power seats without memory are completely controlled through the power seat switch. Battery
voltage is supplied to the power seat switch through the power seat circuit breaker. While the seat
adjuster switches are in an inactive state the switch contacts are closed to the power seat switch
ground circuit. When a power seat switch is pressed to an active state the switch contact is closed
to the battery voltage supply circuit. Each seat adjuster motor is controlled by the power seat
switch through 2 motor control circuits. The seat adjuster motors are bidirectional and the
direction of adjuster motor rotation is determined by which of the adjuster motor control circuits
is switched to battery voltage while the other remains grounded.
Reference Information
Schematic Reference
Driver Seat Schematics
Passenger Seat Schematics
Lumbar Horizontal Motor
Forward Control
1
1
-
-
Lumbar Horizontal Motor
Rearward Control
2
2
-
-
Lumbar Vertical Motor Down
Control
2
2
-
-
Lumbar Vertical Motor Up
Control
2
2
-
-
Rear Vertical Motor Rear
Down Control
1
1
-
-
Rear Vertical Motor Rear Up
Control
1
1
-
-
Recline Motor Forward
Control
1
1
-
-
Recline Motor Rearward
Control
1
1
-
-
Lumbar Switch Ground
-
2
-
-
Power Seat Switch Ground
-
1
-
-
1. Power Seats Inoperative
2. Lumbar Support Inoperative
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Connector End View Reference
Component Connector End Views
Description and Operation
Power Seats System 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 Verification
1. Operate the horizontal, front vertical, and rear vertical switches in both directions.
If the power seat is inoperative in all directions, refer to Power Seat Switch Circuit
Test below.
If 1 or 2 of the seat adjuster motors operate, refer to Seat Adjuster Circuit Test below.
2. Operate the recline in both directions.
If the recline function is inoperative, refer to Recliner Actuator Circuit Test below.
3. Operate the horizontal and vertical lumbar switches in both directions.
If both lumbar functions are inoperative, refer to Lumbar Switch Circuit Test below.
If 1 lumbar function is inoperative, refer to Lumbar Support Circuit Test below.
Circuit/System Testing
Power Seat Switch Circuit Test
1. Disconnect the harness connector at the power seat switch.
2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
If the test lamp does not illuminate, repair the ground circuit for an open/high
resistance.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
3. Verify that a test lamp illuminates between the listed B+ circuit terminal and ground.
With AN3 terminal E
Without AN3 terminal D
If the test lamp does not illuminate, repair the B+ circuit for an open/high resistance or
short to ground.
4. If all circuits test normal, test or replace the power seat switch.
Lumbar Switch Circuit Test
1. Disconnect the harness connector at the lumbar switch.
2. Verify that a test lamp illuminates between the ground circuit terminal E and B+.
If the test lamp does not illuminate, repair the ground circuit for an open/high
resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal G and ground.
If the test lamp does not illuminate, repair the B+ circuit for an open/high resistance or
short to ground.
4. If all circuits test normal, test or replace the lumbar switch.
Seat Adjuster Circuit Test
1. Ignition OFF, disconnect the harness connector at the seat adjuster assembly.
2. Ignition OFF, test for less than 1.0 ohm between the affected control circuit terminal listed
and ground.
Rear vertical terminal 1
Front vertical terminal 2
Horizontal terminal 3
If greater than the specified range, test the control circuit for a short to voltage or an
open/high resistance. If the circuit tests normal, replace the power seat switch.
3. Ignition OFF, test for less than 1.0 ohm between the affected control circuit terminal listed
and ground.
Rear vertical terminal 4
Front vertical terminal 5
Horizontal terminal 6
If greater than the specified range, test the control circuit for a short to voltage or an
open/high resistance. If the circuit tests normal, replace the power seat switch.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
4. Connect a test lamp between the affected control circuit terminals listed.
Rear vertical terminal 1 to terminal 4
Front vertical terminal 2 to terminal 5
Horizontal terminal 3 to terminal 6
5. Operate the affected switch in both directions. The test lamp should turn ON when the
switch is pressed in both directions.
If the test lamp remains OFF during either of the commands, test for a short to ground
on either control circuit. If the circuits test normal, replace the power seat switch.
6. If all circuits test normal, test or replace the seat adjuster.
Recliner Actuator Circuit Test
1. Ignition OFF, disconnect the harness connector at the redline motor.
2. Ignition OFF, test for less than 1.0 ohm between the control circuit terminal A and ground.
If greater than the specified range, test the control circuit for a short to voltage or an
open/high resistance. If the circuit tests normal, replace the power seat switch.
3. Ignition OFF, test for less than 1.0 ohm between the control circuit terminal B and ground.
If greater than the specified range, test the control circuit for a short to voltage or an
open/high resistance. If the circuit tests normal, replace the power seat switch.
4. Connect a test lamp between control circuit terminal A and control circuit terminal B.
5. Operate the recline switch in both directions. The test lamp should turn ON when the switch
is pressed in both directions.
If the test lamp remains OFF during either of the commands, test for a short to ground
on either control circuit. If the circuits test normal, replace the power seat switch.
6. If all circuits test normal, test or replace the recliner motor.
Lumbar Support Circuit Test
1. Ignition OFF, disconnect the harness connector at the lumbar adjuster assembly.
2. Ignition OFF, test for less than 1.0 ohm between the affected control circuit terminal listed
and ground.
Vertical lumbar terminal A
Horizontal lumbar terminal C
If greater than the specified range, test the control circuit for a short to voltage or an
open/high resistance. If circuit tests normal, replace the lumbar switch.
3. Ignition OFF, test for less than 1.0 ohm between the affected control circuit terminal listed
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Power Seats - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Content .. 2695 2696 2697 2698 ..