B1451
DTC B1451
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 B1451 01
- Accessory Power Circuit Short to Voltage
DTC B1451 02
- Accessory Power Circuit Short to Ground
DTC B1451 04
- Accessory Power Circuit Open/High Resistance
Diagnostic Fault Information
Circuit/System Description
The keyless entry control module provides backup controls for the accessory power circuit, through the control circuit, by applying voltage to the circuit. The ignition accessory power is energized when the ignition mode is in ACC or RUN.
Conditions for Running the DTC
B1451 01, B1451 04
* Vehicle power mode is OFF or Crank Request
* Module is awake
* DTC B1451 not already set
* System voltage between 6 and 16 V
B1451 02
* Vehicle power mode is ACC or RUN
* Module is awake
* The DTC is only run when the output is active
* DTC B1451 is not already set
* System voltage between 6 and 16 V
Conditions for Setting the DTC
B1451 01
Accessory output is not active and a short to battery is detected 3 consecutive times.
B1451 02
Accessory output is active and a short to ground is detected 3 consecutive times.
B1451 04
Accessory output is not active and an open circuit is detected 20 consecutive times.
Action Taken When the DTC Sets
B1451 02
The accessory output is deactivated when a short to ground is detected. After 100 ms the output is activated again. This happens 3 times and then the output is deactivated until a new accessory request is received.
B1451 01, B1451 04
No action is taken.
Conditions for Clearing the DTC
* The current DTC will clear when the malfunction is no longer present during a DTC check.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 40, without a repeat of the malfunction.
Diagnostic Aids
* A short to voltage in the ACC control circuit will keep the vehicle bus awake, which can drain the vehicle's battery.
* A short to ground in the extension of this circuit through the body control module can back feed to the keyless entry control module. Check for a short to ground on the accessory circuit on the other side of the accessory pass thru, in the body control module, before replacing the body control module.
Reference Information
Schematic Reference
* Body Control System Schematics [1][2]Body Control Systems
* Power Distribution Schematics Power Distribution Schematics
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation
Power Mode Description and Operation Power Mode
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
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Verify DTC B1330 is not set.
• If the DTC is set, refer to DTC B1325, B1330, B1517, C0800, C0899, C0900, C12E1, C12E2, P0562, P0563, P1A0C, P1A0D, or P1EFC B1325.
2. Ignition OFF, disconnect the X2 harness connector at the K84 keyless entry control module.
3. Verify that a test lamp illuminates between B+ circuit terminal 5 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Ignition OFF, reconnect the X2 harness connector at the K84 keyless entry control module and disconnect the X3 harness connector at the K9 body control module.
5. Ignition OFF, test for less than 1 V between the ignition circuit terminal 5 and ground.
• If greater than the specified range, test the ignition circuit for a short to voltage. If the circuit tests normal, replace the K84 keyless entry control module.
6. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K84 keyless entry control module.
7. If all circuits test normal, replace the K9 body control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Control Module References Control Module References for the appropriate control module replacement, programming and setup