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For 1990-2009 cars only
Makes 🢒 Generic 🢒 2005 🢒 Unit Repair 🢒 Body 🢒 Wiring Systems 🢒 Trunk Release Inoperative

Trunk Release Inoperative Sedan

Diagnostic Fault Information

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

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Switch signal circuit

2

2

--

--

Switch ground circuit

--

2

--

--

Latch motor voltage control circuit

1

1

1

--

Latch motor voltage ground circuit

--

1

--

--

Trunk release relay control circuit

1

1

1

--

1. Trunk release is inoperative from both the switch and keyless entry transmitter.

2. Trunk release is inoperative only from switch.

Circuit/System Description

The rear compartment lid can be released by operating the rear compartment lid release switch or by pressing the rear compartment lid release button on the remote keyless entry transmitter. The gear selector may be in any position, but the vehicle speed must equal 0 for the liftgate to release.

When the ignition is ON, the body control module (BCM) supplies battery positive voltage to the rear compartment lid release switch through the trunk release switch supply voltage circuit. When the rear compartment lid release switch is operated, the trunk release supply voltage circuit is grounded through the switch ground circuit and the voltage is pulled low within the BCM. In response, the BCM applies ground to the trunk release relay control circuit, which energizes the coil side of the trunk relay. The switch side of the trunk relay then closes, supplying battery positive voltage through the relay and the latch motor voltage control circuit to the rear compartment lid latch. The rear compartment lid latch, which is grounded to G302, then releases the rear compartment lid so that it may be manually raised to an open position.

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

Circuit/System Verification
  1. Ignition ON, observe the scan tool Trunk Release Switch parameter while pressing and releasing the rear compartment lid release switch button. The parameter should change between Active and Inactive.
  2. Ignition ON, observe the scan tool Trunk Release Solenoid parameter while commanding the Trunk Release Solenoid ON and OFF The parameter should follow the commands.

Circuit/System Testing

Switch

  1. Ignition OFF, disconnect the harness connector at the rear compartment lid release switch.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the switch ground circuit and ground.
    3. ⇒If greater than 1.0 ohm, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Trunk Release Switch parameter is Inactive.
    4. ⇒If not Inactive, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3-amp fused jumper wire between the signal circuit and ground. Verify the scan tool Trunk Release Switch parameter is Active.
    5. ⇒If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the rear compartment lid release switch.

Relay

  1. Ignition OFF, disconnect the Trunk Relay.
  2. Ignition ON, verify the rear compartment lid latch is inactive.
    3. ⇒If the rear compartment lid latch is still active, test the voltage control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the coil side B+ circuit of the Trunk Relay and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the voltage control circuit for a short to ground. If the circuit tests normal, test or replace the Trunk Relay.
  4. Verify that a test lamp illuminates between the switch side B+ circuit of the Trunk Relay and ground.
    5. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  5. Disconnect the harness connector at the rear compartment lid latch.
  6. Test for less than 1.0 ohm of resistance between the rear compartment lid latch ground circuit and ground.
    7. ⇒If greater than 1.0 ohm, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the rear compartment lid latch.
  8. Connect a 3-amp fused jumper wire between the switch side B+ circuit of the Trunk Relay and the voltage control circuit of the lid latch. Verify that the lid latch activates.
    9. ⇒If the lid latch does not activate, test or replace the rear compartment lid latch.
  9. Connect a test lamp between the trunk release relay control circuit and the coil side B+ circuit of the Trunk Relay.
  10. Command the Trunk Release Solenoid ON and OFF with a scan tool.
    11. ⇒If the test lamp remains ON all the time, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp remains OFF all the time, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  11. If all circuits test normal, test or replace the Trunk Relay.

Component Testing

Switch

  1. Ignition OFF, disconnect the harness connector at the rear compartment lid release switch.
  2. Test for infinite resistance between the trunk release switch supply voltage and ground terminals with the switch in the open position.
    3. ⇒If less than infinite resistance, replace the rear compartment lid release switch.
  3. Test for less than 2 ohms of resistance between the trunk release switch supply voltage and ground terminals with the switch in the closed position.
    4. ⇒If greater than 2 ohms, replace the rear compartment lid release switch.
  4. Test for infinite resistance between each terminal and the lid release switch housing/case.
    5. ⇒If less than infinite resistance, replace the rear compartment lid release switch.

Relay

  1. Ignition OFF, disconnect the Trunk Relay.
  2. Test for 65-90 ohms of resistance between terminals 85 and 86.
    3. ⇒If the resistance is not within the specified range, replace the Trunk Relay.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If less than infinite resistance, replace the relay.
  4. Install a 10-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Measure for less than 2 ohms of resistance between terminals 30 and 87.
    5. ⇒If greater than 2 ohms, replace the relay.

Component Static Test

  1. Ignition OFF, disconnect the harness connector at the lid latch.
  2. Test for 5-8 ohms of resistance between the control terminal and the ground terminal of the lid latch.
    3. ⇒If the resistance is not within the specified range, replace the lid latch.

Component Dynamic Test

Important: Apply power and ground to the rear compartment lid latch for no more than 2 seconds at a time or the actuator could be damaged.

  1. Install a 20-amp fused jumper wire between the voltage control circuit terminal and 12 volts. Momentarily install a jumper wire between the ground terminal and ground.
  2. The lid latch should unlatch.
    3. ⇒If the function does not perform as specified, replace the lid latch.

Repair Instructions

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

    •  Rear Compartment Lid Switch Replacement
    •  Rear Compartment Lid Latch Replacement
    •  Control Module References for BCM replacement, setup, and programming