Hazard Switch: Operation

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

The hazard switch button is slightly recessed in the instrument panel when the switch is in the Off position, and latches at a position that is flush with the outer surface of the instrument panel when in the On position. The hazard switch module circuit board includes miniature relays that produce audible clicking to emulate the sound of a conventional flasher whenever the turn signals or the hazard warning system are activated.

The hazard switch module receives battery voltage on a fused B(+) circuit from a fuse in the Junction Block (JB) at all times for operation of the hazard warning, and on a fused ignition switch output (run) circuit from another fuse in the JB whenever the ignition switch is in the On position for operation of the turn signals. The module receives a path to ground through a splice block secured by a nut to a ground stud on the driver side instrument panel end bracket near the JB.

Inputs to and outputs from the hazard switch module include:

Panel Lamps Dimmer Input - A non-serviceable incandescent bulb soldered onto the hazard switch module provides illumination of the switch button when the exterior lighting is turned On through the fused panel lamps dimmer switch signal circuit. This bulb flashes on and off at full intensity whenever the hazard switch button is activated, regardless of the status of the exterior lighting.
Hazard Switch Input - The combination flasher receives an internal ground input from the hazard switch to request hazard flasher operation.
Multi-Function Switch Input - The combination flasher receives separate ground inputs from the multi-function switch on right and left turn switch sense circuits to request turn signal flasher operation.
Body Control Module Input - The Body Control Module (BCM) can request hazard flasher operation by providing a ground path to the combination flasher through a hazard lamp control circuit.
Turn Signal Output - The combination flasher responds to the flasher inputs by energizing and de-energizing two miniature relays on the module circuit board. These relays control the switch output through the right and left turn signal circuits. One relay controls the right lamps, while the other controls the left.

Because of active electronic elements within the hazard switch module, it cannot be tested using conventional diagnostic tools or procedures. If a problem is noted with turn signal or hazard warning system operation, test and confirm the turn signal and hazard warning lighting circuits are in good condition before replacing the hazard switch module.