GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Liftgate Window Latch Switch Signal

1

2

--

--

Liftgate Latch Switch Signal

1

2

--

--

Liftgate Window Latch Low Reference

--

2

--

--

Liftgate Latch Low Reference

--

2

--

--

1. REAR ACCESS OPEN message is always displayed

2. REAR ACCESS OPEN message inoperative

Circuit/System Description

The REAR ACCESS OPEN message displays and Gate Ajar indicator comes on if the liftgate or liftglass is open while the ignition is in RUN. The IPC receives a serial data message from the liftgate module (LGM) requesting illumination. The LGM receives discrete inputs from 2 ajar switches to indicate the status of the liftgate. The liftgate and liftglass ajar switches are normally open when the liftgate and liftglass are closed. When the liftgate or liftglass is opened, the ajar switch contacts close providing a path to ground.

Reference Information

Schematic Reference

Release Systems Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Door Ajar Indicator Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, observe the scan tool Liftglass Ajar Switch parameter while opening and closing the liftglass. The parameter should change between Closed and Ajar.
  2. If the value does not change, refer to Liftglass Ajar Malfunction.
  3. Observe the scan tool Liftgate Ajar Switch parameter while opening and closing the liftgate. The parameter should change between Closed and Ajar.
  4. If the value does not change, refer to Liftgate Ajar Malfunction.
  5. Observe the driver information center while opening and closing the liftglass and liftgate, the REAR ACCESS OPEN message should display when the liftgate or liftglass is OPEN and the message should turn OFF when the liftglass and liftgate is closed.
  6. If the message is always ON or always OFF, replace the IPC.

Circuit/System Testing

Liftglass Ajar Malfunction

  1. Ignition OFF, disconnect the harness connector at the liftgate window latch assembly.
  2. Test for less than 5 ohms between the low reference circuit terminal B and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal replace the LGM.
  4. Ignition ON, verify the scan tool Liftglass Ajar Switch parameter is Closed.
  5. If not the specified value, test the signal circuit terminal A 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 A and the low reference circuit terminal B. Verify the scan tool Liftglass Ajar Switch parameter is Ajar.
  7. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  8. If all circuits test normal, test or replace the liftgate window latch assembly.

Liftgate Ajar Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the liftgate latch assembly.
  2. Test for less than 5 ohms between the low reference circuit terminal D and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal replace the LGM.
  4. Ignition ON, verify the scan tool Liftgate Ajar Switch parameter is Closed.
  5. If not the specified value, test the signal circuit terminal B 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 B and the low reference circuit terminal D. Verify the scan tool Liftgate Ajar Switch parameter is Ajar.
  7. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  8. If all circuits test normal, test or replace the liftgate latch assembly.

Component Testing

Liftgate Latch Assembly

  1. Ignition OFF, disconnect the harness connector at the liftgate latch assembly.
  2. Test for infinite resistance between the signal terminal B and the low reference terminal D with the switch in the open position.
  3. If not the specified value, replace the liftgate latch assembly.
  4. Test for less than 2 ohms between the signal terminal B and the low reference terminal D with the switch in the closed position.
  5. If greater than the specified range, replace the liftgate latch assembly.

Liftgate Ajar Switch

  1. Ignition OFF, disconnect the harness connector at the liftgate window latch assembly.
  2. Test for infinite resistance between the signal terminal A and the low reference terminal B with the switch in the open position.
  3. If not the specified value, replace the liftgate window latch assembly.
  4. Test for less than 2 ohms between the signal terminal A and the low reference terminal B with the switch in the closed position.
  5. If greater than the specified range, replace the liftgate window latch assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Liftgate Window Latch Replacement
    •  Control Module References for LGM or IPC replacement, programming, and setup