B1971

B1971-POWER LIFTGATE LATCH CINCH - RATCHET PRIMARY SWITCH PERFORMANCE







Theory of Operation

The Primary/Ratchet Switch must remain closed when the liftgate is fully open or between full open and closed positions. The switch will open when the liftgate is fully closed and latched. It is open when the latch is in primary position and closed when the latch is out of primary.

- When Monitored:
Whenever the power liftgate is performing a cinching operation.

- Set Condition:
The ratchet switch did not remain closed during a power cinch operation.





1. DTC PRESENT

NOTE: This DTC will only set during the cinching operation after the four second time out. This may make it difficult to reproduce.

1. With the scan tool, record and erase DTCs.
2. Turn the ignition off, wait 10 seconds, then turn the ignition on.
3. Operate the power liftgate several times if possible.
4. With the scan tool, read ACTIVE DTCs.

Does the scan tool display B1971-POWER LIFTGATE LATCH CINCH - RATCHET PRIMARY 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 the BODY VERIFICATION TEST. Body Verification Test.

2. BINDING LIFTGATE
1. 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.
2. Manually operate the liftgate of a known good vehicle and notice the effort needed to open and close.
3. Compare the effort needed on the disabled liftgate.
4. 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 symptom(s).
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 3

3. POWER LIFTGATE MODULE
1. With the scan tool, monitor the PRIMARY RATCHET SWITCH.
2. Using a screwdriver, click the latch to the second detent while observing the scan tool.
3. Unlatch the latch by pressing the handle switch and observe the scan tool for a change of state.
4. Repeat this step several times while moving the liftgate in different positions and wiggling the harness to check for an intermittent open or shorted circuit.

Did the scan tool show the switch state changing correctly every time?

No

- Go To 4

Yes

- Replace the Power Liftgate Module.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. CHECK THE (Q901) SENSOR GROUND CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Turn all light off.
3. Disconnect the Power Liftgate Latch harness connector.
4. Measure the resistance between ground and the (Q901) Logic Ground circuit in the Liftgate Latch connector.
5. Wiggle the harness while observing the ohmmeter.

Is the resistance below 9.5 Ohms?

Yes

- Go To 5

No

- Repair the (Q901) Logic Ground circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. (G78) LIFTGATE AJAR SWITCH SENSE CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (G78) Liftgate Ajar Switch Sense circuit in the Liftgate Latch connector.

Is the resistance below 1,000 Ohms?

No

- Go To 6

Yes

- Repair the (G78) Liftgate Ajar Switch Sense circuit for a short to ground.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

6. (G78) LIFTGATE AJAR SWITCH SENSE CIRCUIT OPEN




1. Disconnect the Power Liftgate Module C2 harness connector.
2. Measure the resistance of the (G78) Liftgate Ajar Switch Sense circuit between the Power Liftgate Module C2 harness connector and the Power Liftgate Latch harness connector.
3. Wiggle the harness while observing the ohmmeter.

Is the resistance below 2.0 Ohms?

Yes

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

No

- Repair the (G78) Liftgate Ajar Switch Sense circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.