Turn Signal Indicator: Description and Operation

Two turn signal indicator lamps are standard equipment on all instrument clusters. The turn signal indicator lamps are located near the upper edge of the instrument cluster overlay, one on each side of the high beam indicator lamp in the center of the cluster. Each turn signal indicator lamp consists of a International Control and Display Symbol icon for "Turn Warning". These icons are stenciled cutouts in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents these icons from being clearly visible when their lamps are not illuminated. However, a green lens behind each cutout in the opaque layer of the cluster overlay causes the icon to appear in green through the translucent outer layer of the overlay when it is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The turn signal indicator lamps are serviced as a unit with the instrument cluster.

The turn signal indicator lamps give an indication to the vehicle operator that the turn signal (left or right indicator flashing) or hazard warning (both left and right indicators flashing) have been selected. These lamps are hard wired on the instrument cluster electronic circuit board, and are controlled by the turn signal and hazard warning switch inputs to the cluster. The turn signal indicator lamp bulbs are grounded on the instrument cluster electronic circuit board at all times and receive battery current whenever the left and/or right turn signals are turned ON; therefore, these lamps can be ON regardless of the ignition switch position. The turn signal and hazard warning switches are integral to the left multi-function switch on the steering column. The turn signal indicator lamps are connected in series between ground and the output of the turn signal and hazard warning switches, but in parallel with the other turn signal circuits. This arrangement allows the turn signal indicators to remain functional regardless of the condition of the other circuits in the turn signal and hazard warning systems. For more information on the left multi-function switch, (Refer to LAMPS/LIGHTING - EXTERIOR/MULTIFUNCTION SWITCH - OPERATION). The turn signal indicator lamps can be diagnosed using conventional diagnostic tools and methods.