B1978
B1978 - POWER LIFTGATE CLOSE DIRECTION - SECTOR SWITCH PERFORMANCEB1978 - Power Liftgate Close Direction - Sector Switch Performance:
WHEN MONITORED
Whenever the power liftgate in performing a closing operation.
SET CONDITION
The sector switch is unstable during a closing operation.
POSSIBLE CAUSES
- Binding liftgate
- Latch not in home position
- (Q901) Logic ground circuit open
- (Q79) Sector switch sense circuit open
- (Q79) Sector switch sense circuit short to voltage
- (Q79) Sector switch sense circuit short to ground
- Power liftgate latch
- Power liftgate module
Diagnostic Test
1. DTC PRESENT
NOTE: This DTC will only set during the releasing operation after the four second time out. This may make it difficult to reproduce.
With the scan tool, record and erase DTC's.
Turn the ignition off, wait 10 seconds, then turn the ignition on.
Operate the power liftgate several times if possible.
With the scan tool, read ACTIVE DTCs.
Q: Does the scan tool display B1978-POWER LIFTGATE CLOSING OPERATION - SECTOR SWITCH PERFORMANCE?
YES: Go To 2
NO: Using the wiring diagram/schematic as a guide, inspect the wiring and connectors for an intermittent condition. Operate the door several times and check for any binding or other obstructions. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
2. BINDING LIFTGATE
Examine the liftgate for proper fit and alignment, loose/hard or torn seals, misaligned latch striker or anything that would cause an obstruction to proper operation.
Manually operate the liftgate of a known good vehicle and notice the effort needed to open and close. Compare the effort needed on the disabled liftgate.
Especially notice the effort needed to unlatch and close the liftgate.
Q: Does it take more effort to operate the liftgate than it should?
YES: Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 3
3. LATCH HOME POSITION
Ensure the liftgate is closed.
With the scan tool in Inputs/Outputs, read the "Sector Gear Switch Closed" state.
Q: Does the scan tool display TRUE?
YES: Go To 9
NO: Go To 4
4. POWER LIFTGATE LATCH
Disconnect the Power Liftgate Latch connector.
With the scan tool, monitor the Sector Gear Switch Closed.
Connect a jumper wire between the (Q79) Sector Switch Sense circuit and the (Q901) Logic Ground circuit.
Repeat the previous step several times by disconnecting and connecting the jumper while observing the scan tool.
Q: Did the scan tool show the switch state changing correctly every time the jumper was connected and disconnected?
NO: Go To 5
YES: Replace the Power Liftgate Latch. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
5. (Q901) LOGIC GROUND WIRE OPEN
Turn the ignition off.
Turn all lights off.
Measure the resistance between ground and the (Q901) Logic Ground circuit in the Liftgate Latch connector.
Wiggle the harness while observing the ohmmeter.
Q: Is the resistance below 9.5 ohms?
YES: Go To 6
NO: Repair the (Q901) Logic Ground wire for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
6. (Q79) SECTOR SWITCH SENSE WIRE SHORT TO GROUND
Measure the resistance between the (Q901) Logic Ground circuit and the (Q79) Sector Switch Sense circuit in the Liftgate Latch connector.
Wiggle the harness while observing the ohmmeter.
Q: Is the resistance below 100.0 ohms?
NO: Go To 7
YES: Go To 11
7. (Q79) SECTOR SWITCH SENSE WIRE OPEN
Disconnect the Power Liftgate Module C2 connector.
Measure the resistance of the (Q79) Sector Switch Sense circuit between the PLG C2 connector and the Liftgate Latch connector.
Wiggle the harness while observing the ohmmeter.
Q: Is the resistance below 2.0 ohms?
NO: Repair the (Q79) Sector Switch Sense circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
YES: Go To 8
8. (Q79) SECTOR SWITCH SENSE WIRE SHORT TO VOLTAGE
Turn the ignition on.
Measure the voltage between the (Q79) Sector Switch Sense circuit and the (Q901) Logic Ground circuit in the Liftgate Latch connector.
Wiggle the harness while observing the voltmeter.
Q: Is there any voltage present?
NO: Replace the Power Liftgate Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
YES: Repair the (Q79) Sector Switch Sense wire for a short to voltage. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
9. ADJUST LATCH TO HOME POSITION
Close the liftgate.
With the scan tool run the "Latch Home Position Test".
NOTE: This test will try to adjust the sector gear to the Home Position.
With the scan tool in Inputs/Outputs, read the "Sector Gear Switch Closed" state.
Q: Does the scan tool display: FALSE?
NO: Go To 10
YES: Repair complete. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
10. (Q79) SECTOR SWITCH SENSE CIRCUIT SHORT TO GROUND
Disconnect the Power Liftgate Latch connector.
Measure the resistance between the (Q901) Logic Ground circuit and the (Q79) Sector Switch Sense circuit in the Liftgate Latch connector.
Wiggle the harness while observing the ohmmeter.
Q: Is the resistance below 1000.0 ohms?
NO: Replace the Power Liftgate Latch assembly and with the scan tool run the "Latch Home Position Test".
YES: Go To 11
11. (Q79) SECTOR SWITCH SENSE WIRE SHORT TO GROUND
Disconnect the Power Liftgate Module C2 connector.
Measure the resistance between the (Q79) Sector Switch Sense circuit and vehicle ground.
Wiggle the harness while observing the ohmmeter.
Q: Is the resistance below 1000.0 ohms?
NO: Replace the Power Liftgate Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
YES: Repair the (Q79) Sector Switch Sense wire for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test