Chevrolet Silverado / GMC Sierra. Service manual — part 1537

1. Install a scan tool and with all of the doors closed, verify the door ajar switch parameters

are Door Closed.

If any of the door ajar switch parameters are Door Ajar while the doors are closed
refer to Door Ajar Switch Circuit Test below.

2. Open the doors and verify the door ajar switch parameters are Door Ajar.

If any of the door ajar switch parameters are Door Closed while the doors are open
refer to Door Ajar Switch Circuit Test below.

3. If the door ajar switch inputs to the BCM function normally replace the IPC.

Circuit/System Testing

Door Ajar Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the affected door latch.

2. Test for less than 1 ohm between the listed ground circuit terminal and ground.

Driver with power door locks terminal 8

Driver with out power door locks terminal 6

Front passenger and right rear terminal 3

Left rear terminal 6

If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool door ajar switch parameter is Door Closed.

If not the specified value, test the listed signal circuit terminal for a short to ground. If
the circuit tests normal, replace the BCM.

Driver with power door locks terminal 6

Driver with out power door locks terminal 4

Front passenger and right rear terminal 1

Left rear terminal 4

4. Install a 3A fused jumper wire between the listed signal circuit terminal and low reference

circuit terminal. Verify the scan tool door ajar switch parameter is Door Ajar.

Driver with power door locks terminal 6 to terminal 8

Driver with out power door locks terminal 4 to terminal 6

Front passenger and right rear terminal 1 to terminal 3

Left rear terminal 4 to terminal 6

If not the specified value, test the signal circuit for a short to voltage or an open/high
resistance. If the circuit tests normal, replace the affected door switch.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

5. If all circuits test normal, test or replace the affected door latch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Front Side Door Lock Replacement

Rear Door Lock Replacement (Extended Cab Upper) or Rear Door Lock
Replacement (Crew Cab) or Rear Door Lock Replacement (Extended Cab Lower)

Control Module References for the IPC or BCM replacement, setup, and programming

POWER DOOR LOCKS INOPERATIVE - FRONT (W/AN3)

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.

Circuit/System Description

The driver and passenger door lock and side window switches are integrated control module
switch assemblies. The DDS and PDS door lock switches are normally open, 2 position rocker
type switches, with detents for lock and unlock. The DDS and PDS are directly connected to the
respective door lock actuator through the door lock actuator control circuits. When a door lock
or unlock function is activated from the DDS or PDS a GMLAN lock or unlock command is sent
to the other door switch and body control module.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Door Locks Description and Operation

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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

Ignition ON, observe the scan tool Door Lock Actuator Cmd parameter while operating the
affected front door lock switch between lock and unlock. The reading should change from Off to
Lock and Unlock.

If the reading does not change relative to the actual switch position, replace the affected
door lock and side window switch.

Circuit/System Testing

Front Door Lock Circuit Test

1. Disconnect the harness connector at the affected door latch, and connect a test lamp

between the listed lock actuator control circuit terminals.

Driver terminal 5 to 6

Passenger terminal 2 to 3

2. Verify that the test lamp illuminates while the lock switch is operated to lock and unlock.

If the test lamp does not illuminate, test the lock actuator control circuits for an
open/high resistance or a short to ground. If the circuit tests normal replace the
affected door latch.

3. If the circuits test normal replace the affected door lock and side window switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Front Side Door Lock Replacement

Control Module References for DDS or PDS replacement, programming, and setup

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

POWER DOOR LOCKS INOPERATIVE - FRONT (W/O AN3)

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.

Circuit/System Description

The power door locks are controlled by the body control module (BCM) through lock and
unlock printed circuit board relays in the IP fuse block. The driver and passenger door lock
switches are normally open, 2 position rocker type switches, with detents for lock and unlock.
The lock and unlock switch signal circuits are referenced from battery voltage by the BCM and
when a door lock or unlock switch is pressed the signal circuit is closed to ground through the
switch contacts and BCM determines the signal is active. The unlock relays are controlled by the
BCM through driver door and passenger door low side drive control circuits and the lock relays
are controlled through a single high side drive control circuit. During lock or unlock operation,
battery voltage will be supplied to the lock actuators through the energized relays and grounded
through the de-energized relays.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Door Locks Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado