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 GroundDiagnostic 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 Controlled Output | 1 | 1 | 1 | -- |
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 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.
Conditions for Running the DTC
The system voltage is 9-18 V.
Conditions for Setting the DTC
B3898 02
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
Description and Operation
Fuel Fill Door Description and Operation
Electrical Information Reference
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
- Ignition OFF, disconnect the KR94 Fuel Door Release Actuator Relay.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 85 and ground.
- Verify that a test lamp illuminates between the ground circuit terminal 86 and B+.
- 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.
- Disconnect the harness connector at the M27 Fuel Door Release Actuator.
- Test for less than 2 Ω between the M27 Fuel Door Release Actuator door lock control circuit terminal 1 and ground.
- Connect the harness connector at the M27 Fuel Door Release Actuator.
- Connect a 15 A fused jumper wire between the door unlock control circuit terminal 30 and the control circuit terminal 87. Verify the M27 Fuel Door Release Actuator is activated when the door unlock switch is pressed.
- Connect a DMM, set on the diode setting, between the control circuit terminal 86 and ground.
- Command the Fuel Door Release Unlatch with a scan tool. The DMM reading should be greater than 2.5 V or display O.L.
- Command the Fuel Door Release Latch with a scan tool. The DMM reading should be less than 1 V.
- If all circuits test normal, test or replace the KR94 Fuel Door Release Actuator Relay.
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | 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. |
| ⇒ | If the test lamp does not illuminate, test the door unlock control circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the door lock control circuit for an open/high resistance. |
| ⇒ | 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. |
| ⇒ | 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). |
| ⇒ | 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). |
Component Testing
Relay Test
- Ignition OFF, disconnect the KR94 Fuel Door Release Actuator Relay.
- Test for 2 Ω between terminals 85 and 86.
- Test for infinite resistance between the following terminals:
- Test for less than 2 Ω between terminals 30 and 87A.
- Install a 15 A fused jumper wire between 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 the resistance is not within the specified range, replace the KR94 Fuel Door Release Actuator Relay. |
| • | 30 and 86 |
| • | 30 and 87 |
| • | 30 and 85 |
| • | 85 and 87 |
| ⇒ | If not the specified value, replace the KR94 Fuel Door Release Actuator Relay. |
| ⇒ | If greater than the specified range, replace the KR94 Fuel Door Release Actuator Relay. |
| ⇒ | If greater than the specified range, replace the KR94 Fuel Door Release Actuator Relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup and programming |
