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 Descriptors
DTC B251A 01: All Door Unlatch Circuit Short to BatteryDTC B251A 02: All Door Unlatch Circuit Short to Ground
DTC B251A 04: All Door Unlatch Circuit Open
DTC B251B 01: Driver Door Unlatch High Control Circuit Short to Battery
DTC B251B 02: Driver Door Unlatch High Control Circuit Short to Ground
DTC B251B 04: Driver Door Unlatch High Control Circuit Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Driver Door Unlatch Control | B251A 02 | B251A 04 | B251A 01 | -- |
Passenger Door Unlatch Control | B251B 02 | B251B 04 | B251B 01 | -- |
Circuit/System Description
The keyless entry control module and body control module (BCM) control the output functions of the power door latches. These output functions allow the keyless entry control module and BCM to command the power door latch motors to Unlatch.
When the keyless entry control module receives an input from one of the door handle switches, it checks the Lock/Unlock status of the door. If the status of the door is Lock, the keyless entry control module applies the ground for the appropriate unlatch circuit to the BCM and the BCM will unlock the door latch.
Conditions for Running the DTC
The system voltage is 9-18 V.
Conditions for Setting the DTC
B251A 01
The BCM detects a short to battery on the driver door unlatch control circuit.
B251A 02
The BCM detects a short to ground on the driver door unlatch control circuit.
B251A 04
The BCM detects an open circuit on the driver door unlatch control circuit.
B251B 01
The BCM detects a short to battery on the passenger door unlatch control circuit.
B251B 02
The BCM detects a short to ground on the passenger door unlatch control circuit.
B251B 04
The BCM detects an open circuit on the passenger door unlatch control circuit.
Action Taken When the DTC Sets
The power door latches 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
Power Door Locks Description and Operation
Electrical Information Reference
Circuit/System Verification
Command the driver door and passenger door lock actuators to Unlock with the key fob, the doors should perform the Unlock function.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector X1 at the K9 Body Control Module (BCM).
- Ignition ON, test for B+ between the appropriate door unlatch control circuit and B+.
- Ignition ON, test for less than 1 V between the appropriate door unlatch control circuit and ground.
- If all circuits test normal, test or replace the K9 Body Control Module (BCM).
| • | K9 Body Control Module (BCM) terminal 5 |
| • | K9 Body Control Module (BCM) terminal 17 |
| ⇒ | If less than the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the K77 Remote Control Door Lock Receiver (RCDLR). |
| • | K9 Body Control Module (BCM) terminal 5 |
| • | K9 Body Control Module (BCM) terminal 17 |
| ⇒ | If greater than the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the K77 Remote Control Door Lock Receiver (RCDLR). |
| ⇒ | If less than the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the K77 Remote Control Door Lock Receiver (RCDLR). |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM or keyless entry control module replacement, setup and programming
