Diagnostic Routine F
Diagnostic Routine F
Diagnostic Overview
The Power Liftgate Does Not Power Close (Power Open Ok)
Refer to Wiring Diagram Set 109 for schematic and connector information Electrical Diagrams.
Normal Operations and Fault Conditions
When the power liftgate moves in the close direction, the LTM (Liftgate/Trunk Module) monitors the pinch strip switches and position sensor for obstacle detection. If the LTM (Liftgate/Trunk Module) detects an obstacle or a concern with a pinch strip, it either reverses the liftgate or does not allow power close. The LTM (Liftgate/Trunk Module) sends a voltage reference signal to both pinch strips. When a pinch strip is activated, it switches the voltage reference signal to ground. The right and left pinch strip return signal circuits are spliced together.
The LTM (Liftgate/Trunk Module) also monitors the power liftgate latch status once the liftgate closes to a secondary latch position. If the liftgate is unable to obtain a primary latch position, the LTM (Liftgate/Trunk Module) aborts the power close.
DTC Fault Trigger Conditions
Visual Inspection and Diagnostic Pre-checks
- Liftgate alignment
- Liftgate striker alignment
- Pinch strip switches
- Mechanical binding
Pinpoint Test
1. CHECK THE MANUAL OPERATION OF THE LIFTGATE
1. While manually opening and closing the liftgate, check the liftgate for:
- liftgate/wedge alignment
- strut operation (struts should push liftgate open when beyond half open)
- hinges (should move freely)
Does the liftgate open and close correctly?
2. CHECK THE LIFTGATE LEFT/RIGHT PINCH STRIP STATUS (LFT_PINCH / RT_PINCH) OPERATION
1. Using the scan tool, view the LTM (Liftgate/Trunk Module) PIDs (Parameter Identifications).
2. Monitor the LTM (Liftgate/Trunk Module) PIDs (Parameter Identifications) LFT_PINCH and RT_PINCH while activating the left and right pinch strips.
Do the PIDs (Parameter Identifications) states change/agree with the pinch strip status?
3. CHECK THE PINCH STRIP SIGNAL CIRCUIT
1. Disconnect: Inoperative Pinch Strip.
2. For an inoperative left pinch strip, measure:
3. For an inoperative right pinch strip, measure
Is the voltage approximately 5 volts?
4. CHECK THE PINCH STRIP SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
1. Ignition OFF.
2. Disconnect: LTM (Liftgate/Trunk Module) C4174B.
3. Ignition ON.
4. For an inoperative left pinch strip, measure:
5. For an inoperative right pinch strip, measure:
Is any voltage present?
5. CHECK THE PINCH STRIP SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Ignition OFF.
2. Disconnect: LTM (Liftgate/Trunk Module) C4174B.
3. For an inoperative left pinch strip, measure:
4. For an inoperative right pinch strip, measure:
Is the resistance greater than 10,000 ohms?
6. CHECK THE PINCH STRIP SIGNAL CIRCUIT FOR AN OPEN
1. For an inoperative left pinch strip, measure:
2. For an inoperative right pinch strip, measure:
Is the resistance less than 3 ohms?
7. CHECK THE PINCH STRIP RETURN CIRCUIT
1. Ignition ON.
2. For an inoperative left pinch strip, measure:
3. For an inoperative right pinch strip, measure:
Is the voltage approximately 5 volts?
8. CHECK THE PINCH STRIP RETURN CIRCUIT FOR SHORT TO VOLTAGE
1. Ignition OFF.
2. Disconnect: LTM (Liftgate/Trunk Module) C4174B.
3. Ignition ON.
4. For an inoperative left pinch strip, measure:
5. For an inoperative right pinch strip, measure:
Is any voltage present?
9. CHECK THE PINCH STRIP RETURN CIRCUIT FOR AN OPEN
1. For an inoperative left pinch strip, measure:
2. For an inoperative right pinch strip, measure:
Is the resistance less than 3 ohms?
10. CHECK THE DETENT AND FORKBOLT SWITCH PIDs (Parameter Identifications)
1. Using the the scan tool, view 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?
11. 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?
