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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 SRX 🢒 Body 🢒 Body Rear End 🢒 DTC B153A

DTC Descriptor

DTC B153A: Liftgate Latch Switch Signal Circuit

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

The liftgate module uses the liftgate latch to determine at which point the liftgate is during the close sequence. The liftgate latch contains 3 switches: the open switch, ajar switch, and cinch/release switch. As the liftgate latches and is cinched, the open and ajar switch will close. The cinch/release switch is only active when the liftgate latch is actively cinching or releasing the liftgate.

Conditions for Running the DTC

A liftgate open or close function is attempted.

Conditions for Setting the DTC
    • During power open operation, if either the open or ajar switch reports a closed state after the latch is fully released, the DTC will set.
    • During cinching, if the cinch/release switch fails to switch from an open state to a closed state, the DTC will set.

Action Taken When the DTC Sets

On a power open cycle, the liftgate will continue to its full open position and liftgate functions will be suspended.

Conditions for Clearing the DTC
    • The liftgate module no longer detects a circuit fault.
    • A scan tool is used to clear the DTC.

Diagnostic Aids

An open switch or ajar switch stuck in the open or closed position will cause DTC B153A to set.

Reference Information

Schematic Reference

Body Rear End Schematics

Connector End View Reference

Body Rear End Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

Ignition ON, use a scan tool to observe the LGM Latch Pawl Switch and LGM Latch Ratchet Switch parameters while opening and closing the liftgate. Both parameters should read Active with the liftgate open and Inactive with the gate closed.

Circuit/System Testing
  1. Ignition ON, disconnect the harness connector at the liftgate latch.
  2. With the liftgate open, verify with a scan tool that the LGM Latch Pawl Switch and LGM Latch Ratchet Switch parameters are both Active.
    3. ⇒If the LGM Pawl Switch parameter is Inactive, test the open switch signal circuit for an open/high resistance or short to voltage. If all circuits test normal, replace the liftgate module.
    ⇒If the LGM Latch Ratchet Switch parameter is Inactive, test the ajar switch signal circuit for an open/high resistance or short to voltage. If all circuits test normal, replace the liftgate module.
    ⇒If both the LGM Latch Pawl Switch and LGM Latch Ratchet Switch parameters are Inactive, test the low reference circuit for an open or short to voltage. If all circuits test normal, replace the liftgate module.
  3. With the liftgate closed, verify with a scan tool that both the LGM Latch Pawl Switch and LGM Latch Ratchet Switch parameters are both Inactive.
    4. ⇒If the LGM Pawl Switch parameter is Active, test the open switch signal circuit for a short to ground. If all circuits test normal, replace the liftgate module.
    ⇒If the LGM Latch Ratchet Switch parameter is Active, test the ajar switch signal circuit for a short to ground. If all circuits test normal, replace the liftgate module.
  4. Verify with a scan tool that the LGM Latch Ratchet Switch parameter is Inactive.
    5. ⇒If not Inactive, test the cinch/release switch circuit for a short to ground. If all circuits test normal, replace the liftgate module.

Component Testing
  1. Ignition OFF, disconnect the harness connector at the liftgate latch.
  2. Test for infinite resistance between the open switch terminal and the low reference terminal with the latch in the open position.
    3. ⇒If less than infinite resistance, replace the liftgate latch.
  3. Test for infinite resistance between the sector switch terminal and the low reference terminal with the latch in the open position.
    4. ⇒If less than infinite resistance, replace the liftgate latch.
  4. Test for infinite resistance between the cinch/release switch terminal and the low reference terminal with the latch in the open position.
    5. ⇒If less than infinite resistance, replace the liftgate latch.
  5. Test for less than 1 ohm of resistance between the open switch terminal and the low reference terminal with the latch in the closed position.
    6. ⇒If greater than 1 ohm, replace the liftgate latch.
  6. Test for less than 1 ohm of resistance between the sector switch terminal and the low reference terminal with the latch in the closed position.
    7. ⇒If greater than 1 ohm, replace the liftgate latch.
  7. Test for less than 1 ohm of resistance between the cinch/release switch terminal and the low reference terminal with the latch in the closed position
    8. ⇒If greater than 1 ohm, replace the liftgate latch.
  8. Test for infinite resistance between each terminal and the liftgate latch housing.
    9. ⇒If greater than infinite resistance, replace the liftgate latch.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Liftgate Latch Replacement
    •  Control Module References for liftgate module replacement, setup, and programming