Diagnostic Routine A
Diagnostic Routine A
Diagnostic Overview
The Power Liftgate Is Inoperative
Refer to Wiring Diagram Set 109 for schematic and connector information Electrical Diagrams.
Normal Operations and Fault Conditions
The LTM (Liftgate/Trunk Module) receives battery voltage at all times through the BCM (Body Control Module) fuse 9 (10A) and BJB (Battery Junction Box) fuse 7 (30A). The LTM (Liftgate/Trunk Module) has a dedicated ground circuit.
REFER to Body Closures for a detailed description on power liftgate operation.
DTC Fault Trigger Conditions
Visual Inspection and Diagnostic Pre-checks
- BCM (Body Control Module) fuse 9 (10A)
- BJB (Battery Junction Box) fuse 7 (30A)
Pinpoint Test
1. CHECK THE OPERATION OF THE POWER LIFTGATE SWITCHES
1. Vehicle in park.
2. NOTE: Make sure the power liftgate is enabled (on) in the vehicle message center.
Close the liftgate to the full closed position (manually, if necessary).
3. Activate the power liftgate from the power liftgate control switch (instrument panel).
4. Activate the power liftgate from an RKE (Remote Keyless Entry) transmitter.
5. Activate the power liftgate from the exterior liftgate switch.
Does the power liftgate power open from any switch?
2. RETRIEVE THE DTCs (Diagnostic Trouble Codes) FROM THE LTM (Liftgate/Trunk Module)
1. Retrieve the recorded LTM (Liftgate/Trunk Module) DTCs (Diagnostic Trouble Codes) from the self-test.
Are any LTM (Liftgate/Trunk Module) DTCs (Diagnostic Trouble Codes) recorded?
3. CHECK FOR VOLTAGE TO THE LTM (Liftgate/Trunk Module)
1. Ignition OFF.
2. Disconnect: LTM (Liftgate/Trunk Module) C4174A.
3. Measure:
Are the voltages greater than 11 volts?
4. CHECK THE LTM (Liftgate/Trunk Module) GROUND FOR AN OPEN
1. Measure:
Is the resistance less than 3 ohms?
5. CHECK THE DETENT AND FORKBOLT SWITCH PIDs (Parameter Identifications)
1. Using a scan tool, view the LTM (Liftgate/Trunk Module) PIDs (Parameter Identifications).
2. Operate the liftgate manually while monitoring the LTM (Liftgate/Trunk Module) PIDs (Parameter Identifications):
- Detent Switch Status (DETENTSW)
- Forkbolt Switch Status (FORKBLT_S)
- Forkbolt Secondary Switch (FKSWSEC)
3. NOTE: The liftgate is in the primary position when the liftgate is in the full closed position. The liftgate is in the unlatch position when the liftgate is open and completely out of the striker.
NOTE: If detent switch is active in the fully unlatched position, manually attempt to rotate the forkbolt towards the latched position.
Begin with the liftgate in the open position, then slowly close the liftgate into each of the latch positions specified.
Do the switch states agree with the table?
6. CHECK THE OPTICAL SENSOR 1 (OPT_SEN_1) AND 2 (OPT_SEN_2) STATUS PIDs (Parameter Identifications)
1. Open the liftgate to the full OPEN position.
2. Using the scan tool, view LTM (Liftgate/Trunk Module) PIDs (Parameter Identifications).
3. Monitor the LTM (Liftgate/Trunk Module) PIDs (Parameter Identifications) OPT_SEN_1 and OPT_SEN_2 while slowly closing the liftgate.
Do both of the PID (Parameter Identification) values alternate from ACTIVE to INACTIVE while the liftgate is moving?
7. CHECK THE MOTOR AND LATCH CIRCUITS FOR A SHORT TO VOLTAGE
1. Ignition OFF.
2. Disconnect: LTM (Liftgate/Trunk Module) C4174A.
3. Disconnect: Power Liftgate Motor.
4. Disconnect: Power Liftgate Latch.
5. Ignition ON.
6. Measure:
Is any voltage present?
8. CHECK THE MOTOR AND LATCH CIRCUITS FOR A SHORT TO GROUND
1. Ignition OFF.
2. Measure:
Are the resistances greater than 10,000 ohms?
9. CHECK THE MOTOR AND LATCH CIRCUITS FOR AN OPEN
1. For the power liftgate motor, measure:
2. For the power liftgate latch, measure:
Are the resistances less than 3 ohms?
10. CHECK THE UNLATCH OPERATION
1. Connect: Power Liftgate Latch.
2. Close and latch the liftgate.
3. NOTICE: Do not apply power and ground to the unlatch actuator circuits for more than a few seconds or damage to the motor may occur.
Momentarily connect a fused jumper wire:
Does the unlatch/cinching motor activate?
11. CHECK THE POWER LIFTGATE MOTOR OPERATION
1. Connect: Power Liftgate Motor.
2. Place the liftgate in the fully closed and unlatched position.
3. NOTICE: Do not apply power and ground to the power liftgate motor circuits for more than a few seconds or damage to the motor may occur.
Momentarily connect a fused jumper wire:
Does the power liftgate motor operate?
12. CHECK FOR CORRECT LTM (Liftgate/Trunk Module) OPERATION
1. Ignition OFF.
2. Disconnect and inspect all LTM (Liftgate/Trunk Module) connectors.
3. Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
4. Reconnect all the LTM (Liftgate/Trunk Module) connectors. Make sure they seat and latch correctly.
5. Operate the system and determine if the concern is still present.
Is the concern still present?
