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DTC B3938

DTC B3938

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.


DTC Descriptor

DTC B3938 02

Fuel Door Actuator Lock Circuit Short to Ground

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Doors Lock Control

B3135 02, 1

1

1

-

Fuel Door Relay Coil Control

B3938 02

1

1

-

Fuel Door Relay Control

1

1

1

-

Fuel Door Relay Coil Ground

-

1

1

-

1. Fuel Filler Door Release Inoperative



Circuit/System Description

The locking and unlocking of the fuel door is a function of the power door lock system. The fuel door unlatch 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 unlatch actuator , unlocking the fuel door.

Conditions for Running the DTC

The system voltage is 9-18 V.

Conditions for Setting the DTC

The BCM detects a short to ground on the fuel filler door relay control circuit.

Action Taken When the DTC Sets

The remote fuel filler door will be inoperative.

Conditions for Clearing the DTC


• This DTC will be current for as long as the fault is present.

• When the fault is no longer present, the DTC will be a history DTC.

• A history DTC will clear after 50 ignition cycles.


Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel Fill Door 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, command the Fuel Door Release ON and OFF with a scan tool. The fuel filler door should lock and unlock.

Circuit/System Testing


1. Ignition OFF, disconnect the X2 connector at the X53 Fuse Block - Rear.

2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 5 X2 and ground.

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

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 28 X2 and ground.

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

6. Connect a 15 A fused jumper wire between the door unlock control circuit terminal 28 X2 and the control circuit terminal 13 X2. Verify the M27 Fuel Door Unlatch Actuator is activated when the door unlock switch is pressed.

7. If the M27 Fuel Door Unlatch 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 Unlatch Actuator.

8. If all circuits test normal, test or replace the X53 Fuse Block - Rear.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Fuel Tank Filler Door Lock Actuator Replacement

• Control Module References for BCM replacement, setup and programming