B312A
DTC B312A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B312A 02
- Door Latch Actuators Enable Relay Control Circuit
DTC B312A 05
- Door Latch Actuators Enable Relay Control Circuit
Diagnostic Fault Information
Circuit/System Description
When the rear access panel release switch is pressed, the voltage level within the rear access panel signal circuit drops, the body control module (BCM) will detect the voltage drop and in turn will then send a serial data message to the instrument panel cluster (IPC). If the vehicle speed is less than 3 km/h (1 mph) the IPC will energize the door lock relay causing the switch side of the relay to close and provide a ground for the rear access panel actuators.
Conditions for Running the DTC
When the door lock relay is being actively commanded by the IPC.
Conditions for Setting the DTC
B312A 02
The IPC detects a short to ground in the door lock relay control circuit.
B312A 05
The IPC detects a short to battery or an open/high resistance in the door lock relay control circuit or an open/high resistance in the door lock relay ground circuit.
Action Taken When the DTC Sets
Rear access panel release will malfunction.
Conditions for Clearing the DTC
* The 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
Release Systems Schematics (Release Systems Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Access Panel Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Programming and Relearning (Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Rear Access Panel Lock Relay Cmd. parameter while pressing and releasing the rear access panel release switch, the parameter should change between Inactive and Active.
Circuit/System Testing
1. Ignition OFF, disconnect the Door Lock relay.
2. Test for less than 5 ohms between the ground circuit terminal 2 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal 1 and the ground circuit terminal 2 and ground.
4. Ignition ON, command the Rear Access Panel Lock Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the IPC.
• If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the IPC.
5. If all circuits test normal, test or replace the Door Lock relay.
Component Testing
1. Ignition OFF, disconnect the Door Lock relay.
2. Test for 60-180 ohms between terminals 1 and 2.
• If not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
* 1 and 3
* 1 and 5
* 2 and 3
* 2 and 5
• If not the specified value, replace the relay.
4. Install a 20A fused jumper wire between relay terminal 1 and 12V. Install a jumper wire between relay terminal 2 and ground. Test for less than 2 ohms between terminals 3 and 5.
• If greater than the specified range, replace the relay.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Programming and Relearning (Programming and Relearning) for IPC replacement, setup and programming