B1451

DTC B1451

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 Descriptor
DTC B1451 02
- Accessory Power Circuit Short to Ground

DTC B1451 05
- Accessory Power Circuit Short to Battery or Open




Circuit/System Description

The body control module (BCM) provides an accessory voltage output, enabled in Run and Accessory power modes. The accessory voltage circuit provides power for engine control module (ECM), transmission control module (TCM), and wiper run/acc relay.


Conditions for Running the DTC

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.


Conditions for Setting the DTC

* The BCM detects a short to ground in the accessory power circuit for greater then 5 seconds when the output is active.
* The BCM detects a short to battery or an open in the accessory power circuit for greater then 1 second when the output is inactive.



Action Taken When the DTC Sets

The BCM will disable the accessory power output until the next ignition cycle.


Conditions for Clearing the DTC

* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.



Reference Information
Schematic Reference

Power Moding Schematics (Power Moding Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Retained Accessory Power (RAP) Description and Operation (Retained Accessory Power (RAP) Description and Operation)
* Power Mode Description and Operation (Power Mode 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 Testing

1. Ignition OFF, disconnect the wiper run/acc relay.
2. Verify DTC B1451 is set.

• If DTC is not set, replace the wiper run/acc relay.

3. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
4. Ignition ON, verify a test lamp illuminates between the underhood fuse block terminal E3 and ground.

• If test lamp does not illuminate, test the accessory voltage circuit between the under hood fuse block terminal E3 and the BCM terminal 22 for a short to ground or an open/high resistance. If circuit tests normal, replace the BCM.

5. Ignition OFF, connect the X2 harness connector at the underhood fuse block.
6. Disconnect the X1 harness connector at the ECM and X400 harness connector at the TCM.
7. Ignition ON, verify a test lamp illuminates between the ECM accessory voltage circuit terminal 18 and ground.

• If the test lamp does not illuminate, test the accessory voltage circuit between the ECM terminal 18, and the underhood fuse block and the TCM terminal 9 and the underhood fuse block for a short to ground or an open/high resistance.

8. Connect the X1 harness connector at the ECM.
9. Verify DTC B1451 is not set.

• If DTC is set, replace the ECM.

10. If all circuits test normal, replace the TCM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Control Module References (Programming and Relearning) for BCM, TCM, and ECM replacement, setup, and programming