P257D

P257D- ENGINE HOOD SWITCH 1 CIRCUIT RANGE / PERFORMANCE - HEV





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

Hybrid Electric Vehicles (HEV) utilize hood switch's to prevent Autostart and Autostop when the hood is open. This is similar to conventional vehicles which use a single hood switch to prevent remote start when the hood is open. Hood switch 1 communicates via CAN message to NGC from the Front Control Module (FCM). Hood switch 2 is a direct input to the Powertrain Control Module. Readings of hood switch 1 and hood switch 2 are checked against the calibration thresholds to determine the switch state. There are four possible states: Hood Closed, Hood Open (Ajar), Open Circuit and Indeterminate.

- When Monitored:
Continuously

- Set Condition:
Hood Switch 1 Voltage greater than 3.5 or greater than.2 of a volt.





WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. TEST FOR INTERMITTENT CONDITION

NOTE: Open the hood and make sure the Hood Ajar Switch is connected before proceeding.

1. With the scan tool, record and erase DTCs.
2. Close the hood.
3. Cycle the ignition from on to off.
4. Turn the ignition on.
5. Open then close the hood.
6. With the scan tool, read DTCs.

Does the scan tool display P257D- ENGINE HOOD SWITCH 1 CIRCUIT RANGE / PERFORMANCE?

Yes

- Go To 2

No

- The conditions that set this DTC are no longer present.
- Perform the INTERMITTENT CONDITION diagnostic procedure. . Intermittent Condition Test

2. HOOD AJAR SWITCH INSTALLED DAMAGED OR OUT OF CALIBRATION
Inspect the retainer ring, hood ajar switch and hood for:

- Hood misalignment
- Hood slam overtravel - due to missing rubber cap on the hood stop
- Hood switch striker mispositioned
- Accidental full depression

Were there any problems found?

Yes

- Repair as necessary.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 3

3. HOOD AJAR SWITCH OPEN
1. Disconnect the Hood Ajar Switch harness connector.
2. Depress the plunger of the hood ajar switch and measure the resistance between the two terminals of the switch.

Is the resistance approximately 1k Ohms?

Yes

- Go To 4

No

- Replace the Hood Ajar Switch.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. (Z926) GROUND CIRCUIT OPEN




1. Using a 12-volt test light connected to 12-volts, check the (Z926) Ground circuit.

Does the test light illuminate?

Yes

- Go To 5

No

- Repair the (Z926) Ground circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. (G70) HOOD AJAR SWITCH SENSE CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the FCM IPM 49 way harness connector.
2. Turn the ignition on.
3. Measure the voltage between the (G70) Hood Ajar Switch Sense circuit and ground.

Is there any voltage present?

Yes

- Repair the (G70) Hood Ajar Switch Sense circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 6

6. (G70) HOOD AJAR SWITCH SENSE CIRCUIT OPEN




1. Turn the ignition off.
2. Measure the resistance of the (G70) Hood Ajar Switch Sense circuit between the FCM IPM 49 way harness connector and the Hood Ajar Switch harness connector.

Is the resistance below 2.0 Ohms?

Yes
Go To 7
No

- Repair the (G70) Hood Ajar Switch Sense circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

7. FRONT CONTROL MODULE (FCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Hood Switch 1 and the Front Control Module (FCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Hood Switch 1 and the Front Control Module (FCM) connectors.
4. Search for any Technical Service Bulletins (TSBs) that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace and program the Front Control Module (FCM).
- Perform the BODY VERIFICATION TEST. Body Verification Test.