Hood Ajar Warning Indicator: Description and Operation

Hood Ajar Indicator Description and Operation

Hood Ajar Indicator System Components

* The BCM
* The vehicle integration control module
* The driver information center
* Hood latch assembly

Hood Ajar Operation

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

The hood ajar switch functions as a safety device so that when the hood is open and the ignition is ON, the engine starts and runs, this is necessary to prevent the engine from starting unexpectedly when the battery voltage drops below a critical level while a technician is performing diagnostics/maintenance/repairs in the engine compartment.

When the ignition is ON, the vehicle integration control module 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 vehicle integration control module.