B1978
B1978 - Power Liftgate Close Direction Sector Switch Performance
For a complete wiring diagram, refer to.
• When Monitored: Whenever the power liftgate is performing a closing operation.
• Set Condition: The sector switch is unstable prior to a closing operation.
Theory of Operation
The sector switch is essentially a park switch for the latch. When the latch is running a cinch or release operation, the switch is closed. After the cinch or release is complete, the PLGM will reverse direction of the latch until the switch is open.
Test Step 1 - DTC Present
• 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 DTCs.
• 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.
Does the scan tool display B1978 - Power Liftgate Closing Operation Sector Switch Performance?
Yes
• Go to Test Step 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 the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 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.
Does it take more effort to operate the liftgate than it should?
Yes
• Refer to service information for the related symptoms.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Go to Test Step 3
Test Step 3 - Latch Home Position
• Ensure the liftgate is closed.
• With the scan tool in inputs/outputs, read the "sector gear switch closed" state.
Does the scan tool display TRUE?
Yes
• Go to Test Step 9
No
• Go to Test Step 4
Test Step 4 - Power Liftgate Latch
• Disconnect the power liftgate latch harness connector.
• With the scan tool, monitor the sector gear switch closed.
• Connect a jumper wire between the sector switch sense circuit and the logic ground circuit.
• Repeat the previous step several times by disconnecting and connecting the jumper while observing the scan tool.
Did the scan tool show the switch state changing correctly every time the jumper was connected and disconnected?
No
• Go to Test Step 5
Yes
• Replace the power liftgate latch.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 5 - Check the Logic Ground Circuit for an Open
• Turn the ignition OFF.
• Turn all lights off.
• Measure the resistance between ground and the logic ground circuit.
• Wiggle the harness while observing the ohmmeter.
Is the resistance less than 9.5 ohms?
Yes
• Go to Test Step 6
No
• Repair the logic ground circuit for an open.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 6 - Check the Sector Switch Sense Circuit for a Short to Ground
• Measure the resistance between the sensor ground circuit and the sector switch sense circuit in the liftgate latch connector.
• Wiggle the harness while observing the ohmmeter.
Is the resistance less than 10k ohms?
No
• Go to Test Step 7.
Yes
• Go to Test Step 11
Test Step 7 - Check the Sector Switch Sense Circuit for an Open
• Disconnect the power liftgate module C2 harness connector.
• Measure the resistance of the sector switch sense circuit between the power liftgate C2 harness connector and the power liftgate latch harness connector.
• Wiggle the harness while observing the ohmmeter.
Is the resistance less than 2.0 ohms?
No
• Repair the sector switch sense circuit for an open.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Yes
• Go to Test Step 8
Test Step 8 - Check the Sector Switch Sense Circuit for a Short to Voltage
• Turn the ignition ON.
• Measure the voltage of the sector switch sense circuit.
• Wiggle the harness while observing the voltmeter.
Is there any voltage present?
No
• Replace the power liftgate module.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Yes
• Repair the sector switch sense circuit for a short to voltage.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 9 - Adjust Latch to Home Position
• Close the liftgate.
• With the scan tool run the "latch home position test".
• 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.
Does the scan tool display FALSE?
No
• Go to Test Step 10
Yes
• Repair complete.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 10 - Check the Sector Switch Sense Circuit for a Short to the Logic Ground Circuit
• Disconnect the power liftgate latch harness connector.
• Measure the resistance between the logic ground circuit and the sector switch sense circuit in the power liftgate latch connector.
• Wiggle the harness while observing the ohmmeter.
Is the resistance less than 10k ohms?
No
• Replace the power liftgate latch assembly and use the scan tool to run the power liftgate "latch home position test".
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Yes
• Go to Test Step 11
Test Step 11 - Check the Sector Switch Sense Circuit for a Short to Ground
• Disconnect the power liftgate module C2 harness connector.
• Measure the resistance between ground and the sector switch sense circuit.
• Wiggle the harness while observing the ohmmeter.
Is the resistance less than 10k ohms?
No
• Replace the power liftgate module.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Yes
• Repair the sector switch sense wire for a short to ground.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior