B312A
DTC B312A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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
The instrument panel cluster (IPC) monitors the circuit and if it detects a request for the rear access panels to activate, it will send B+ voltage to the interlock relay provided the vehicle speed is less than 3 km/h (1 mph). This will energize the relay and provide ground for the access panel actuators.
Conditions for Running the DTC
The system voltage is 9-16 volts.
Conditions for Setting the DTC
B312A 02
The IPC detects a short to ground in the LOCK relay coil control circuit.
B312A 05
The IPC detects a short to battery or an open/high resistance in the LOCK relay coil control circuit or an open/high resistance in the LOCK relay coil ground circuit.
Action Taken When the DTC Sets
Rear access panels 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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (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 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 relay coil ground circuit terminal and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the relay coil control circuit terminal 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 85 and 86.
• If not within the specified range, replace the Door Lock relay.
3. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If not the specified value, replace the Door Lock relay.
4. Install a 25-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 ohms between terminals 30 and 87.
• If greater than the specified range, replace the Door Lock 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))
* Control Module References (Programming and Relearning) for IPC replacement, setup and programming