The locking and unlocking of the fuel door is a function of the power door lock system. The fuel door release actuator is supplied by the door lock signal circuit and the driver door unlock signal circuit which is switched through the fuel door relay. The fuel door relay coil is controlled by the body control module (BCM). When the vehicles doors are unlocked, the body control module (BCM) will respond by applying voltage to the fuel door relay coil control circuit. This energizes the coil causing the switch contacts to close. With the switch contacts closed, the driver door unlock circuit supplies B+ or ground to the fuel door release actuator , unlocking the fuel door.

Schematic Reference

Release Systems Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel Fill Door Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Observe the operation of the power door locks and fuel filler door while using the power door lock switch. The fuel filler door should Lock and Unlock as commanded along with the door locks.

1. Ignition OFF, disconnect the KR94 Fuel Door Release Actuator Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 85 and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the ground circuit terminal 86 and B+.

⇒	If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the KR94 Fuel Door Release Actuator Relay.

4. Press the door unlock button on the door lock switch and verify that a test lamp illuminates between the door unlock control circuit terminal 30 and ground.

⇒	If the test lamp does not illuminate, test the door unlock control circuit for an open/high resistance.

5. Disconnect the harness connector at the M27 Fuel Door Release Actuator.
6. Test for less than 2 Ω between the M27 Fuel Door Release Actuator door lock control circuit terminal 1 and ground.

⇒	If greater than the specified range, test the door lock control circuit for an open/high resistance.

7. Connect the harness connector at the M27 Fuel Door Release Actuator.
8. Connect a 15 A fused jumper wire between the door unlock control circuit terminal 30 and the control circuit terminal 87a. Verify the M27 Fuel Door Release Actuator is activated when the door unlock switch is pressed.

⇒	If the M27 Fuel Door Release Actuator does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the M27 Fuel Door Release Actuator.

9. Connect a DMM, set on the diode setting, between the control circuit terminal 86 and ground.
10. Command the Fuel Door Release Unlatch with a scan tool. The DMM reading should be greater than 2.5 V or display O.L.

⇒	If less than the specified value, test the control circuit for a short to voltage or short to ground. If the circuits test normal, replace the K9 Body Control Module (BCM).

11. Command the Fuel Door Release Latch with a scan tool. The DMM reading should be less than 1 V.

⇒	If greater than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

12. If all circuits test normal, test or replace the KR94 Fuel Door Release Actuator Relay.

Relay Test

1. Ignition OFF, disconnect the KR94 Fuel Door Release Actuator Relay.
2. Test for 60-200 Ω between terminals 85 and 86.

⇒	If not within the specified range, replace the KR94 Fuel Door Release Actuator Relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If less than the specified value, replace the KR94 Fuel Door Release Actuator Relay.

4. Install a 3 A fused jumper wire between the relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒	If greater than specified range, replace the KR94 Fuel Door Release Actuator Relay.

Fuel Door Release Actuator Test

1. Ignition OFF, disconnect the harness connector at the M27 Fuel Door Release Actuator.
2. Install a 25 A fused jumper wire between the lock control terminal 2 and 12 V. Momentarily install a jumper wire between the unlock control terminal 1 and ground. The M27 Fuel Door Release Actuator should perform the Lock/ Unlock function.

⇒	If the function does not perform as specified, replace the M27 Fuel Door Release Actuator.

3. Reverse the jumper wires; the M27 Fuel Door Release Actuator should perform the Unlock/Lock function.

⇒	If the function does not perform as specified, replace the M27 Fuel Door Release Actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.