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B153A



DTC B153A

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC B153A 08
- Liftgate Latch Switch Signal Circuit Signal Invalid




Diagnostic Fault Information






Circuit/System Description

The ratchet, pawl, and sector switches are part of the latch motor assembly and are used by the liftgate control module (LGM) to determine the state of the latch during the process of latching or unlatching. Each of the latch switch signal circuits are supplied battery voltage through a resistor and monitored within the LGM. The latch switches share a common low reference circuit from the LGM and when the switch contacts close the signal circuit goes low and the LGM determines the switch to be active. The full open switch is a limit switch mounted on the gear motor assembly alongside the swing arm gear. The full open switch signal circuit is supplied battery voltage through a resistor and monitored within the LGM. When the liftgate reaches the full open position, the switch signal circuit is closed to the low reference circuit and the signal circuit voltage goes low.


Conditions for Running the DTC

Battery voltage must be between 9-16 volts.


Conditions for Setting the DTC

DTC B153A 08 will set when the LGM detects signal mismatches from any of the following switches:

* Full open switch
* Pawl switch
* Ratchet switch
* Sector switch



Actions Taken When the DTC Sets

The power liftgate system may be inoperative or function incorrectly.


Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* You issue a scan tool CLEAR DTCs command.



Diagnostic Aids

* A liftgate latch open switch or ajar switch stuck in the open or closed position will cause DTC B153A 08 to set.
* Whenever the LGM loses power or is disconnected, the ignition must be cycled OFF then ON.



Reference Information
Schematic Reference

Liftgate Schematics (Liftgate Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Liftgate Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)


Circuit/System Verification

1. Ignition ON, observe the scan tool Pawl Sw. parameter while opening and closing the liftgate. The reading should change between ACTIVE and INACTIVE.

• If the reading does not change as the liftgate is opened and closed, refer to Liftgate Latch Switch Signal Malfunction.

2. Observe the scan tool Ratchet Sw. parameter while opening and closing the liftgate. The reading should change between ACTIVE and INACTIVE.

• If the reading does not change as the liftgate is opened and closed, refer to Liftgate Latch Switch Signal Malfunction.

3. Observe the scan tool Sector Sw. parameter while opening and closing the liftgate. The reading should change between ACTIVE and INACTIVE.

• If the reading does not change as the liftgate is opened and closed, refer to Liftgate Latch Switch Signal Malfunction.

4. Observe the scan tool Full Open Sw. parameter while opening and closing the liftgate. The reading should change between ACTIVE and INACTIVE.

• If the reading does not change as the liftgate is opened and closed, refer to Liftgate Full Open Switch Signal Malfunction.




Circuit/System Testing


Liftgate Latch Switch Signal Malfunction
1. Ignition OFF, disconnect the harness connector at the liftgate latch assembly.
2. Ignition ON, verify that a test lamp illuminates between B+ and the low reference circuit terminal 2.

• If the test lamp illuminate does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.

3. Ignition ON, verify the scan tool Pawl Sw. parameter is INACTIVE.

• If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the LGM.

4. Ignition ON, verify the scan tool Ratchet Sw. parameter is INACTIVE.

• If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the LGM.

5. Ignition ON, verify the scan tool Sector Sw. parameter is INACTIVE.

• If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the LGM.

6. Install a 3A fused jumper wire between the signal circuit terminal 5 and low reference circuit terminal 2. Verify the scan tool Pawl Sw. parameter is ACTIVE.

• If not the specified value, test the signal circuit terminal 5 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.

7. Install a 3A fused jumper wire between the signal circuit terminal 6 and low reference circuit terminal 2. Verify the scan tool Ratchet Sw. parameter is ACTIVE.

• If not the specified value, test the signal circuit terminal 6 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.

8. Install a 3A fused jumper wire between the signal circuit terminal 4 and low reference circuit terminal 2. Verify the scan tool Sector Sw. parameter is ACTIVE.

• If not the specified value, test the signal circuit terminal 4 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.

9. If all circuits test normal, test or replace the liftgate latch assembly.



Liftgate Full Open Switch Signal Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the LGM.
2. Ignition ON, verify the scan tool Full Open Sw. parameter is INACTIVE.

• If not the specified value, replace the LGM.

3. Reconnect the X3 harness connector at the LGM.
4. Open the liftgate and verify the scan tool Full Open Sw. parameter is ACTIVE.

• If not the specified value, test the signal circuit terminal 4 for a short to voltage or an open/high resistance. If the circuit tests normal, test the low reference circuit terminal 6 for an open/high resistance. If the circuits tests normal, test or replace the liftgate motor assembly.

5. Close the liftgate and verify the scan tool Full Open Sw. parameter is INACTIVE.

• If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, test or replace the liftgate motor assembly.

6. If all circuits test normal, replace the LGM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Liftgate Close Actuator Motor Replacement (Service and Repair)
* Liftgate Close Actuator Motor Control Module Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for LGM replacement, setup, and programming


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