B1972-POWER LIFTGATE LATCH RELEASE - RATCHET PRIMARY SWITCH PERFORMANCE
For a complete wiring diagram Refer to Section 8W
- When Monitored:
Whenever the power liftgate is manually being moved or at full open position, or at the end of a power opening cycle.
- Set Condition:
The pawl switch was detected as grounded but the ratchet switch remained open.
| Possible Causes |
| (Q901) SENSOR GROUND CIRCUIT OPEN |
| (G78) LIFTGATE AJAR SWITCH SENSE CIRCUIT OPEN |
| (G78) LIFTGATE AJAR SWITCH SENSE SHORT TO VOLTAGE |
| POWER LIFTGATE LATCH |
| POWER LIFTGATE MODULE |
Diagnostic Test
1. DTC PRESENTNOTE: 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 B1972–POWER LIFTGATE LATCH RELEASE - RATCHET PRIMARY SWITCH PERFORMANCE?
Yes
- Go To2
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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 symptom(s).
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Go To 3
3. POWER LIFTGATE MODULE
With the scan tool, monitor the PRIMARY RATCHET SWITCH.
Using a screwdriver, click the latch to the second detent while observing the scan tool.
Unlatch the latch by pressing the handle switch and observe the scan tool for a change of state.
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 To4
Yes
- Replace the Power Liftgate Module in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
4. CHECK THE (Q901) LOGIC GROUND CIRCUIT FOR AN OPEN
Turn the ignition off.
Disconnect the Power Liftgate Latch harness connector.
Measure the resistance between ground and the (Q901) Logic Ground circuit.
Wiggle the harness while observing the ohmmeter.
Is the resistance below 9.5 ohms?
Yes
- Go To6
No
- Repair the (Q901) Logic Ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
5. (G78) LIFTGATE AJAR SWITCH SENSE CIRCUIT OPEN
Disconnect the Power Liftgate Module C2 harness connector.
Measure the resistance of the (G78) Liftgate Ajar Switch Sense circuit between the Power Liftgate Module C2 connector and the Power Liftgate Latch connector.
Wiggle the harness while observing the ohmmeter.
Is the resistance below 2.0 ohms?
Yes
- Go To6
No
- Repair the (G78) Liftgate Ajar Switch Sense circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
6. (G78) LIFTGATE AJAR SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
Turn the ignition on.
Measure the voltage of the (G78) Liftgate Ajar Switch Sense circuit.
Wiggle the harness while observing the ohmmeter.
Is there voltage present?
Yes
- Replace the Power Liftgate Latch in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Repair the (G78) Liftgate Ajar Switch Sense circuit for a short to voltage.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).