Combination Flasher: Operation

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 (IC) 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.