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

Trunk release relay switch B+ circuit

1

1

--

--

Trunk Release Control Circuit

2

2

2

--

Trunk Release Relay Controlled Output Circuit

B3265 00

B3265 00

B3265 00

--

Trunk release relay control circuit

1

1

1

--

Switch ground circuit

--

2

2

--

Rear Compartment Lid Latch Ground

--

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 depressing the rear release button in the glove box or holding either front power door lock switch to the unlock position for a minimum of 2 seconds or by pressing the rear compartment release button on the key fob. The transmission must be in the PARK position for the rear compartment 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 battery positive voltage 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 G402, then releases the rear compartment lid so that it may be manually raised to an open position.

Diagnostic Aids

The RR TRN/SIG fuse also provides battery positive voltage to the BCM which provides power to many systems including the trunk release relay control which, if open, will cause the rear compartment lid latch to become inoperative.

Reference Information

Schematic Reference

Release Systems Schematics

Connector End View Reference

Vehicle Access Connector End Views

Description and Operation

Luggage Compartment Description and Operation

Electrical Information Reference

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

Scan Tool Reference

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

Circuit/System Verification

  1. Ignition ON, observe the scan tool Int Trunk Sw parameter while pressing and releasing the rear compartment lid release switch button. The parameter should change between Active and Inactive.
  2. If the Trunk Rel Sw parameters do not change, refer to Trunk Release Switch Malfunction.
  3. Command the Trunk Release with a scan tool, the rear compartment lid latch should release the trunk lid.
  4. If the rear compartment lid latch does not release, refer to Rear Compartment Lid Latch Malfunction.

Circuit/System Testing

Trunk Release Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the rear compartment lid release switch.
  2. Test for less than 1.0 ohm of resistance between the ground circuit terminal A and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Int Trunk Sw parameter is Inactive.
  5. If not the specified value, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool Int Trunk Sw parameter is Active.
  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 BCM.
  8. If all circuits test normal, test or replace the rear compartment lid release switch.

Rear Compartment Lid Latch Malfunction

  1. Ignition OFF, disconnect the TRUNK RELSE relay.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between terminal 143 and ground.
  3. If greater than the specified range, test for an open/high resistance.
  4. Ignition ON, verify that a test lamp does not illuminate between terminal 140 and ground.
  5. If the test lamp illuminates, test the control circuit for a short to voltage.
  6. Verify that a test lamp illuminates between terminal 142 and ground.
  7. 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 TRUNK RELSE fuse is open, test terminal 140 for a short to ground.
  8. Ignition OFF, disconnect the harness connector at the rear compartment lid latch.
  9. Ignition OFF, test for less than 1.0 ohm of resistance between the rear compartment lid latch ground circuit terminal 3 and ground.
  10. If greater than the specified range, test the ground circuit for an open/high resistance.
  11. Connect the harness connector at the rear compartment lid latch.
  12. Ignition ON, connect a 10A fused jumper wire between terminal 142 and terminal 140. Verify the rear compartment lid latch is activated.
  13. If the rear compartment lid latch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the rear compartment lid latch.
  14. Connect a test lamp between terminal 139 and terminal 143.
  15. Command the Trunk Release ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
  16. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  17. If all circuits test normal, test or replace the TRUNK RELSE relay.

Component Testing

Relay Test

  1. Ignition OFF, disconnect the TRUNK RELSE relay.
  2. Test for 60-180 ohms of resistance between terminals 85 and 86.
  3. If the resistance is not within the specified range, replace the relay.
  4. Test for infinite resistance between the following terminals:
  5. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    If not the specified value, replace the relay.
  6. Install a 25A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87.
  7. If greater than the specified range, replace the relay.

Rear Compartment Lid Latch

  1. Ignition OFF, disconnect the harness connector at the Rear Compartment Lid Latch.
  2. Install a 10-amp fused jumper wire between the control circuit terminal 4 and 12 volts. Install a jumper wire between the ground circuit terminal 3 and ground. Verify the rear compartment lid latch activates.
  3. If the latch does not perform as specified, replace the Rear Compartment Lid Latch.

Rear Compartment Lid Release Switch

  1. Ignition OFF, disconnect the harness connector at the Rear Compartment Lid Release Switch.
  2. Test for infinite resistance between the signal terminal C and the ground circuit terminal A with the switch in the open position.
  3. If not the specified value, replace the Rear Compartment Lid Release Switch.
  4. Test for less than 2.0 ohms between the signal terminal C and the ground circuit terminal A with the switch in the closed position.
  5. If greater than the specified range, replace the Rear Compartment Lid Release Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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