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Chevrolet Silverado / GMC Sierra. Manual - part 1539
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 a test lamp connected to ground illuminates on the supply side of the unlock
fuses 1 and 2 when an unlock switch is activated.
If the test lamp does not illuminate at either fuse perform the Rear Door Lock Relay
Control Circuit Test.
If the test lamp does not illuminate at one fuse only perform the appropriate Actuator
Circuit Test.
2. Verify that a test lamp connected to ground illuminates on the supply side of the lock fuses 1
and 2 when a lock switch is activated.
If the test lamp does not illuminate at either fuse perform the Rear Door Lock Relay
Control Circuit Test.
If the test lamp does not illuminate at one fuse only perform the appropriate Actuator
Circuit Test.
Circuit/System Testing
Rear Door Lock Relay Control Circuit Test
1. Verify that a test lamp connected to battery voltage illuminates when connected to each of
the lock and unlock 1 and 2 fuses in the IP fuse block.
If the test lamp does not illuminate at all 4 fuses replace the IP fuse block.
2. Disconnect the BCM connector X7.
3. Verify that the rear door lock actuators unlock when a fused jumper wire is connected to the
unlock relay control circuit terminal 9 and briefly applied to ground.
If the rear door lock actuators do not unlock test the unlock relay control circuit for an
open/high resistance. If the circuit tests normal replace the IP fuse block.
4. Verify that the rear door lock actuators lock when a fused jumper wire is connected to the
lock relay control circuit terminal 7 and briefly applied to battery voltage.
If the rear door lock actuators do not lock test the lock relay control circuit for an
open/high resistance. If the circuit tests normal replace the IP fuse block.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
5. If the circuits test normal replace the BCM.
Rear Door Lock Actuator Circuit Test
1. Verify that a test lamp connected to battery voltage illuminates when connected to each of
the lock and unlock 1 and 2 fuses in the IP fuse block.
If the test lamp does not illuminate at all 4 fuses replace the IP fuse block.
2. Disconnect the affected rear door latch connector and connect a test lamp across the lock
actuator control circuit terminals.
3. Verify that the test lamp illuminates briefly when a lock and unlock switch is activated.
If the test lamp does not illuminate in both switch positions test the lock actuator
control circuits for an open/high resistance or short to ground. If the circuits test
normal replace the IP fuse block.
4. If the circuits test normal replace the affected door latch.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Rear Door Lock Replacement (Extended Cab Upper) or Rear Door Lock
Replacement (Crew Cab) or Rear Door Lock Replacement (Extended Cab Lower)
Instrument Panel Electrical Center or Junction Block Replacement - Left Side
Control Module References for BCM replacement, programming, and setup
REPAIR INSTRUCTIONS
LOCK CYLINDER BINDING
In many cases, applying the proper lubrication can correct the following conditions:
Binding or sticking door lock cylinders
Difficulty in inserting and removing the keys
For lubricating the above components, use lubricant GM P/N 12346241 or equivalent.
Do not use penetrating lubricants such as GM P/N 1052949 or WD-40®. Penetrating lubricants
wash out the original lubrication. Penetrating lubricants eventually evaporate, leaving little or no
lubricating material. However, when using penetrating lubricants in order to thaw or in order to
loosen the lock cylinder components, refer to steps 2-4 in the procedure below for the proper
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
methods of lubrication.
Repair lock cylinders frozen in cold weather by using the following procedure:
1. While carefully avoiding damage to the painted surfaces, apply heat to the cylinder with a
heat gun.
2. Using a paper clip or a similar item, hold the door shutter open.
Force air into the cylinders using compressed air through a blow gun attachment.
3. While holding the shutter door open, inject small amounts of a recommended lubricant into
the cylinder.
4. Work the key into the cylinder repeatedly.
Wipe away any excess lubrication from the key.
DOOR LOCK CYLINDER REPLACEMENT
Fig. 9: View Of Front Side Door Lock Cylinder & Components
Courtesy of GENERAL MOTORS CORP.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
ENDGATE LOCK CYLINDER REPLACEMENT
Fig. 10: View Of Endgate Lock Cylinder & Retaining Clip
Courtesy of GENERAL MOTORS CORP.
Callout
Component Name
Preliminary Procedures
1. Position the door window as needed for service.
2. Remove the door trim panel. Refer to Front Side Door Trim Panel Replacement
(YE9) or Front Side Door Trim Panel Replacement (SLT) .
3. Remove the water deflector. Refer to Front Side Door Water Deflector
Replacement .
4. Remove the outside door handle. Refer to Front Side Door Outside Handle
Replacement.
1
Front Side Door Lock Rod
2
Front Side Door Lock Cylinder Pawl Retainer Clip
Tip: Remove the clip that attaches the cylinder to the door handle.
3
Front Side Door Lock Cylinder Pawl
4
Front Side Door Lock Cylinder
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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