Liberty 4WD L4-2.4L DOHC VIN 1 (2005)
Hazard Warning Flasher: Description and Operation
Hazard Switch
The combination flasher is integral to the hazard switch unit located behind the hazard switch button near the center of the instrument panel. The
combination flasher is a smart relay that functions as both the turn signal system and the hazard warning system flasher. The combination flasher contains
active electronic Integrated Circuitry (IC) elements.
This flasher is designed to handle the current flow requirements of the factory-installed lighting. If supplemental lighting is added to the turn signal lamp
circuits, such as when towing a trailer with lights, the combination flasher will automatically try to compensate to keep the flash rate the same.
The combination flasher cannot be repaired or adjusted and, if faulty or damaged, the hazard switch unit must be replaced.
The combination flasher has the following inputs and outputs: fused B(+), fused ignition switch output, right turn signal sense, left turn signal sense, and
one output each for the right and left turn signal circuits. The combination flasher also receives an internal input through the hazard switch and, on
vehicles equipped with the optional Vehicle Theft Security System (VTSS), receives an input from the Body Control Module (BCM) in order to flash the
turn signal lamps as an optical alert feature of that system.
Battery voltage is supplied to the flasher on a fused B(+) circuit so that the flasher can perform the hazard warning flasher function, regardless of the
ignition switch position. The flasher also receives battery voltage on a separate fused ignition switch output (run-start) circuit to perform the turn signal
flasher function.
The Integrated Circuit (1C) within the combination flasher contains the logic that controls the flasher operation and the flash rate. The IC receives
separate sense ground inputs from the multi-function switch for the right and left turn signals, and from the hazard switch contacts or the BCM for the
hazard warning signals. A special design feature of the combination flasher allows it to "sense" that a turn signal circuit or bulb is not operating, and
provide the driver an indication of the condition by flashing the remaining bulbs in the affected circuit at a higher rate (120 flashes-per-minute or
higher).
Because of the active electronic elements within the combination flasher, it cannot be tested with conventional automotive electrical test equipment. If
the combination flasher is believed to be faulty, test the turn signal and hazard warning systems before replacing the flasher. If no problems are found,
replace the hazard warning switch with a known good unit to confirm system operation.