Doors, Hood and Trunk: Testing and Inspection

Hood Ajar Indicator/Message Malfunction

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.

Diagnostic Fault Information






Circuit/System Description

The body control module (BCM) applies B+ to the hood ajar signal 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 BCM by pulling down the applied voltage based on the position of the switch.

Reference Information
Schematic Reference

Immobilizer Schematics
Connector End View Reference

Component Connector End Views
Description and Operation

Keyless Entry System Description and Operation
Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode.
2. Observe the scan tool Hood Ajar Switch parameter. With the hood open, the Hood Ajar Switch parameter should be Open. With the hood closed, the Hood Ajar Switch parameter should be Closed.

• If the parameter does not change
Refer to Circuit/System Testing.

• If the parameter changes

3. All OK.

Circuit/System Testing

1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B55 hood ajar switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohm between the ground circuit terminal C and ground.

• If 10 ohm or greater

1. Vehicle OFF
2. Test for less than 2 ohm in the ground circuit end to end.

• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, repair the open/high resistance in the ground connection.

• If less than 10 ohm

3. Vehicle in Service Mode.
4. Test for B+ between the signal circuit terminal B and ground.

• If less than B+

1. Vehicle OFF, disconnect the harness connector at the BCM.
2. Test for infinite resistance between the B+ circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If Infinite resistance.

3. Test for less than 2 ohm in the B+ circuit end to end.

• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the BCM.

• If B+

5. Vehicle OFF, disconnect the X4 and X7 harness connector at the K9 BCM. Vehicle in Service Mode.
6. Test for less than 1 V between the signal circuit terminal B and ground.

• If 1 V or greater
Repair the short to voltage on the circuit.

• If less than 1 V

7. 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 Service and Repair
* Control Module References for BCM replacement, programming and setup