B1978

B1978-POWER LIFTGATE CLOSE DIRECTION - SECTOR SWITCH PERFORMANCE





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
Prior to the Power Liftgate performing a power close operation.

- Set Condition:
The sector switch is closed when it should be open during a power close.





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 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 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.
Does it take more effort to operate the liftgate than it should?

Yes

- Refer to the Service information for the related procedure(s).
- 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.
Does the scan tool display TRUE?

Yes

- Go To 5

No

- Go To 4

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 (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.
Did the scan tool show the switch state changing correctly every time the jumper was connected and disconnected?

No

- Go To5

Yes

- Replace the Power Liftgate Latch.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

5. ADJUST LATCH TO HOME POSITION
Ensure the liftgate is closed.
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.
Does the scan tool display: FALSE?

No

- Go To 6

Yes

- Repair complete.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

6. CHECK THE (Q79) SECTOR SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND




Disconnect the Power Liftgate Latch harness connector.
Measure the resistance between ground and the (Q79) Sector Switch Sense circuit.
Wiggle the harness while observing the ohmmeter.
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".
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

Yes

- Go To 7

7. (Q79) SECTOR SWITCH SENSE CIRCUIT SHORTED TO GROUND




Disconnect the Power Liftgate Module C2 harness connector.
Measure the resistance between ground and the (Q79) Sector Switch Sense circuit in the Liftgate Latch harness connector.
Wiggle the harness while observing the ohmmeter.
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".
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

Yes

- Go To 8

8. (Q79) SECTOR SWITCH SENSE CIRCUIT SHORTED TO THE (Q901) LOGIC GROUND CIRCUIT




Measure the resistance between the (Q901) Logic Ground circuit and the (Q79) Sector Switch Sense circuit in the Power Liftgate Latch harness connector.
Wiggle the harness while observing the ohmmeter.
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 circuit for a short to the (Q901) Logic Ground circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.