Hood Ajar Warning Indicator: Testing and Inspection
Hood Ajar Indicator/Message Malfunction
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 Instructionsprovides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
When the ignition is ON, the body control module (BCM) supplies a voltage signal to the hood ajar switch through the hood ajar switch signal circuit. When the hood is opened, the signal circuit is connected to ground through the hood ajar switch ground circuit and the voltage is pulled low within the BCM. In response, the BCM sends a serial data message to the driver information center in the instrument panel cluster to display the Hood Open message.
Reference Information
Schematic Reference
Release Systems Schematics
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation
Hood Ajar Indicator Description and Operation Description and Operation
Electrical Information Reference
* 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 Referencesfor scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool BCM Hood Position parameter while opening and closing the hood, the parameter should change between Open and Closed.
2. Ignition ON, observe the scan tool VICM Hood Position Switch parameter while opening and closing the hood, the parameter should change between Open and Closed
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B55 hood ajar switch.
2. Test for less than 30 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 the scan tool BCM Hood Position Switch parameter is Closed.
• If not the specified value, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K9 BCM
4. Install a 3 A fused jumper between the signal circuit terminal B and the ground circuit terminal C. Verify the scan tool BCM Hood Position parameter is Open.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
5. Ignition ON, verify the scan tool VICM Hood Position Switch parameter is Closed.
• If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the A694 vehicle integration control module.
6. Install a 3 A fused jumper between the signal circuit terminal A and the ground circuit terminal C. Verify the scan tool Hood Position Switch parameter is Open.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the A694 vehicle integration control module.
7. If all circuits test normal, test or replace the B55 hood ajar switch.
Component Testing
1. Ignition OFF, disconnect the harness connector at the B55 hood ajar switch.
2. Test for infinite resistance between the signal terminal A and the ground terminal C with the switch in the open position.
• If not the specified value, replace the B55 hood ajar switch.
3. Test for less than 2.0 ohm between the signal terminal A and the ground terminal C with the switch in the closed position.
• If greater than the specified range, replace the B55 hood ajar switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Hood Primary and Secondary Latch Replacement Service and Repair
* Control Module References Control Module Referencesfor BCM and vehicle integration control module replacement, programming and setup