Component Tests and General Diagnostics
DIAGNOSIS AND TESTING - POWER LOCKS
The most reliable, efficient, and accurate means to diagnose the Power Lock System requires the use of a DRB III(R) scan tool and the proper Diagnostic Procedures.
WARNING: REFER TO RESTRAINTS BEFORE ATTEMPTING ANY DOOR, SEAT, STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
When trouble shooting problems with the Power Locks System, always verify that the power lock switch is functional. If the doors, rear liftgate, or fuel door do not lock/unlock with the power lock switch, the following system components should be analyzed:
- Power door lock switch
- Body Control Module (BCM)
- Remote Keyless Entry Relay
- Power Lock/Actuator assemblies
- Sentry Key Remote Entry Module (SKREEM)
- Central Locking Pump/Security System Module
- Pneumatic supply lines
There are three main Electronic Control Modules which are interdependent on each other to complete lock/unlock commands, they are the BCM, SKREEM, and Central Locking Pump/Security System Module. These modules cannot be adjusted or repaired. For complete power locks diagnosis procedures, refer to Power Locks Electrical Diagnostics.
PNEUMATIC SUPPLY LINES
The Power Lock Actuators are controlled by pneumatic supply lines that transfer either vacuum or pressure from the Central Locking Pump/Security System Module to the component through distributors. When trouble shooting problems related to the pneumatic portion of the power lock system, a preliminary inspection should be performed to determine that the pneumatic supply lines and harness connectors are free from kink or blockage damage. If necessary, repairs to the pneumatic supply lines or harness connectors must be performed first before proceeding with additional Power Lock System diagnosis.
SUPPLY LINE/ACTUATOR TESTING
When trouble shooting a pneumatic supply line or actuator for the Power Lock System, perform the following steps:
Entire System
1. Disconnect the pneumatic supply line connected to the Central Locking Pump/Security System Module.
2. Using a hand held vacuum pump, connect an appropriate rubber hose 2 in. (50 mm) long to the disconnected pneumatic supply line.
3. Apply 600 mbar (17.7 in. Hg) vacuum to the pneumatic supply line for 1 minute.
If after 1 minute the vacuum loss is less than 30 mbar (.9 in. Hg), the pneumatic supply lines and actuators are not the cause of the fault. If after 1 minute the vacuum loss is greater than 30 mbar (.9 in. Hg), perform the Pneumatic Actuator Test.
Pneumatic Actuator Test
1. Disconnect the pneumatic supply line (1) connected to the pneumatic actuator.
2. Using a hand held vacuum pump, connect an appropriate rubber hose 2 in. (50 mm) long to the disconnected pneumatic actuator.
3. Apply 600 mbar (17.7 in. Hg) vacuum to the pneumatic actuator for 1 minute.
If after 1 minute the vacuum loss is less than 30 mbar (.9 in. Hg), perform the Pneumatic Line Test. If after 1 minute the vacuum loss is greater than 30 mbar (.9 in. Hg), replace the pneumatic actuator.
Pneumatic Line Test
1. Block off one end of the pneumatic supply line and connect a hand held vacuum pump to the other end of the supply line.
2. Apply 300 mbar (8.9 in. Hg) vacuum to the pneumatic supply line for 1 minute.
If after 1 minute the vacuum loss is 0 mbar (0 in. Hg), then check for pressure and vacuum at the Central Locking Pump/Security System Module. If after 1 minute the vacuum loss is greater than 0 mbar (0 in. Hg), replace the pneumatic supply line.