GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 DTS 🢒 Body 🢒 Body Rear End 🢒 Trunk Release Inoperative

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

The body control module (BCM) applies voltage to the trunk release relay control circuit based on trunk release switch signal from the interior trunk release switch. The rear compartment lid latch assembly is supplied battery voltage via the TRUNK RELEASE fuse through the TRUNK RELEASE relay. When the interior trunk release switch is pressed, the trunk release control circuit is grounded. This input will request the BCM to apply voltage to the trunk release relay control circuit, which will switch the TRUNK RELEASE relay. With the relay contacts closed, battery voltage is supplied to the rear compartment lid latch assembly, opening the rear compartment.

Reference Information

Schematic Reference

Body Rear End Schematics

Connector End View Reference

Body Rear End Connector End Views

Description and Operation

Luggage Compartment Description and Operation

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
  1. Ignition ON, observe the scan tool Valet Switch parameter. The Valet Switch parameter should read Inactive.
    2. ⇒If the parameter does not read Inactive, turn off the valet function using the Valet Switch. If unable to turn off the valet function, refer to Valet Switch Always Active in Circuit/System Testing.
  2. Observe the Int. Trunk Sw. parameter while pressing the interior trunk release switch. The reading should change between Active and Inactive.
    3. ⇒If the reading does not change between Active and Inactive, refer to Trunk Release Inoperative in Circuit/System Testing.
  3. Command the Trunk Release output control ON with a scan tool. The trunk latch should release.
    4. ⇒If the trunk latch does not release, refer to Trunk Release Inoperative in Circuit/System Testing.

Circuit/System Testing

Valet Switch Always Active

  1. Ignition OFF, disconnect the harness connector at the valet switch.
  2. Test for less than 1.0 ohm of resistance between the ground circuit terminal A and ground.
    3. ⇒If not the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Valet Switch parameter is Inactive.
    4. ⇒If not the specified value, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3-A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool Valet Switch parameter is Active.
    5. ⇒If not the specified value, test the signal circuit terminal B 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 valet switch.

Trunk Release Inoperative

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Ignition ON, verify the scan tool Int. Trunk Sw. parameter is Inactive.
    3. ⇒If not the specified value, test the signal circuit terminal 10 for a short to ground. If the circuit tests normal, replace the BCM.
  3. Install a 3-amp fused jumper wire between the signal circuit terminal 10 and ground. With a scan tool, verify the Int. Trunk Sw. parameter is Active.
    4. ⇒If not the specified value, test the signal circuit terminal 10 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Connect the harness connector at the headlamp switch.
  5. With a scan tool, verify the trunk release switch parameter cycles between ACTIVE and INACTIVE with each press of the trunk release switch.
    6. ⇒If the parameter does not cycle, replace the trunk release switch
  6. Ignition OFF, disconnect the Trunk Release relay.
  7. Test for less than 1.0 ohm of resistance from the ground circuit terminal 143 and ground.
    8. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  8. Verify that a test lamp illuminates between the B+ circuit terminal 142 and ground.
    9. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  9. Disconnect the harness connector at the rear compartment lid latch.
  10. Test for less than 1.0 ohm of resistance between the ground circuit terminal 3 and ground.
    11. ⇒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. Connect a 10-amp fused jumper between the B+ circuit terminal 142 and the control circuit terminal 140. Verify the trunk release is active.
    13. ⇒If the trunk release does not activate, test the control circuit for an open/high resistance. If the Trunk Release fuse is blown, test the control circuit for a short to ground. If the circuit tests normal, test or replace the rear compartment lid latch.
  13. Connect a test lamp between the control circuit terminal 139 and the ground circuit 143.
  14. Command the Trunk Release output control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    15. ⇒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.
  15. If all circuit test normal, test or replace the Trunk Release relay.

Component Testing

Valet Switch

  1. Ignition OFF, disconnect the harness connector at the valet switch.
  2. Test for infinite resistance between the signal terminal B and the ground circuit terminal A in the open position.
    3. ⇒If not the specified value, replace the valet switch.
  3. Test for less than 2.0 ohms of resistance between the signal terminal B and the ground circuit terminal A in the closed position.
    4. ⇒If greater than the specified range, replace the valet switch.

Trunk Release Relay

  1. Ignition OFF, disconnect the trunk release 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.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If greater than the specified range, replace the valet switch.
  4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms of resistance between terminals 30 and 87.
    5. ⇒If greater than 2.0 ohms, replace the relay.

Rear Compartment Lid Latch

  1. Ignition OFF, 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 trunk release actuator activates.
    3. ⇒If the actuator does not perform as specified, replace the rear compartment lid latch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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