Vehicle Theft Security Hood Ajar Switch - Operation - Export

OPERATION

The hood ajar switch is a normally closed switch that is held open as the spring-loaded switch plunger is depressed by the inner hood panel reinforcement when the hood panel is closed and latched. When the hood is opened, the spring-loaded switch plunger extends from the switch body and the switch contacts are closed. The switch is connected in series between ground and the hood ajar switch sense input of the Totally Integrated Power Module (TIPM). The TIPM uses an internal resistor pull up to monitor the state of the hood ajar switch contacts.

The components of the switch self-adjustment feature include an integral stop on the shaft of the plunger and a ribbed, ratcheting sleeve at the top of the switch body from which the plunger extends. With the switch mounting collar secured in its mounting bracket, the plunger is depressed by the hood inner reinforcement as the hood is closed. As the plunger is depressed, the plunger stop contacts the top of the sleeve and the sleeve is driven downward, ratcheting through the switch mounting collar until the hood is fully closed and latched. The ribs on the sleeve are engaged within the mounting collar to maintain this adjusted position.

The hood ajar switch and the hard wired circuits for the switch may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the TIPM, the ElectroMechanical Instrument Cluster (EMIC), sometimes referred to as the Cab Compartment Node (CCN), or the electronic communication between these modules. The most reliable, efficient, and accurate means to diagnose the hood ajar switch, the TIPM, the EMIC/CCN or the electronic communication related to hood ajar switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.