Bolted Exterior Body Panels and Closures

DTC P257D-P257F

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Diagnostic Repair Verification for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC P257D
- Engine Hood Switch Performance

DTC P257E
- Engine Hood Switch Circuit Low Voltage

DTC P257F
- Engine Hood Switch Circuit High Voltage

Diagnostic Fault Information





Circuit/System Description

The hybrid powertrain control module 2 applies B+ to the hood ajar signal 2 circuit and monitors the voltage to determine the position of the hood. The hood ajar switch contains a multiplexed resistor. This resistor will vary the voltage seen by the hybrid powertrain control module 2 by pulling down the applied voltage based on the position of the switch.

Conditions for Running the DTC

Propulsion system is active.

Conditions for Setting the DTC

P257D

The hood ajar switch signal 2 voltage as measured by the hybrid powertrain control module 2 is not within a valid voltage range.

P257E

The hybrid powertrain control module 2 detects a short to ground in the hood ajar signal input to the hybrid powertrain control module 2.

P257F

The hybrid powertrain control module 2 detects a short to voltage or an open/high resistance in the hood ajar signal input to the hybrid powertrain control module 2.

Action Taken When the DTC Sets

The engine will start and run whenever the ignition is ON and the vehicle speed is less than 5 kph (3 mph).

Conditions for Clearing the DTC

DTCs P257D, P257E, and P257F are Type B DTCs.

Circuit/System Verification

Ignition ON, observe the scan tool ECM Hood Position parameter. With the hood open, the Hood Position parameter should be Open. With the hood closed, the Hood Position parameter should be Closed.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the B55 hood ajar switch.
2. Ignition OFF, test for less than 5 ohm between the ground circuit terminal C and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify DTC P257F is set as current.

• If the DTC is not set, test the signal circuit for a short to ground. If the circuit tests normal, replace the hybrid powertrain control module 2.

4. Install a 5 A fused jumper wire between the signal circuit terminal A and ground. Verify DTC P257E is set as current.

• If the DTC is not set, test the signal circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the hybrid powertrain control module 2.

5. If all circuits test normal, test or replace the B55 hood ajar switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Hood Primary and Secondary Latch Replacement
* Control Module References Control Module References for hybrid powertrain control module 2 replacement, programming and setup