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

Midgate Ajar Signal

1

2

--

--

Midgate Ajar Switch Signal

1

2

1

--

Midgate Latch Ground

--

2

--

--

1. Midgate ajar indicator always ON

2. Midgate ajar indicator inoperative

Circuit/System Description

The latch ajar switches provide a single input to the midgate control module. The switch signal circuit is supplied accessory voltage through a resistor and monitored by the midgate control module. When the midgate is opened both of the latch ajar switches close and the circuit is pulled low. The midgate control module provides an ajar signal to the body control module through the midgate ajar indicator signal circuit. The body control module supplies the signal circuit with accessory voltage through a resistor and monitors the voltage level. When the midgate is ajar the midgate control module will ground the ajar indicator signal circuit and the voltage monitored by the body control module will drop indicating the circuit is active.

Reference Information

Schematic Reference

Release Systems Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Midgate 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

Ignition ON, observe the scan tool Rear Closure Ajar Sw parameter while opening and closing the midgate, the parameter should change from Active to Inactive.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the midgate window motor.
  2. Ignition ON, verify the scan tool Rear Closure Ajar Sw parameter is Inactive.
  3. If not the specified value, test the signal circuit terminal 12 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal 12 and ground. Verify the scan tool Rear Closure Ajar Sw parameter is Inactive.
  5. 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 BCM.
  6. Ignition OFF, connect the harness connector at the midgate window motor and disconnect the harness connector at the left midgate latch.
  7. Ignition ON, verify the scan tool Rear Closure Ajar Sw parameter is Inactive.
  8. If not the specified value, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the midgate window motor.
  9. Install a 3A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool Rear Closure Ajar Sw parameter is Active.
  10. 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 midgate window motor.
  11. Connect the harness connector at the left midgate latch and disconnect the harness connector at the right midgate latch.
  12. Ignition OFF, test for less than 1 ohm between the ground circuit terminal B and ground.
  13. If greater than the specified range, test the ground circuit for an open/high resistance.
  14. Ignition ON, verify the scan tool Rear Closure Ajar Sw parameter is Inactive
  15. If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, test or replace the left midgate latch.
  16. Install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Rear Closure Ajar Sw parameter is Active.
  17. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the left midgate latch.
  18. If all circuits test normal, test or replace the right midgate latch.

Component Testing

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Midgate Latch Replacement
    •  Midgate Window Regulator Module Motor Replacement
    •  Control Module References for BCM or IPC replacement, programming, and setup.