Summit Wagon FWD L4-2350cc 2.4L SOHC (1995)
Turn Signal Lamp: Description and Operation
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When the ignition switch is turned to "ON" position, the electricity flows to the flasher unit through the hazard switch and the Tr1 inside the
flasher unit turns on. (Tr2 remains off.)
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When the turn signal switch is turned to "LH" (or "RH") position, because the Tr2 base current flows through D2, R4, the turn signal switch, the
turn signal light and the ground to turn on Tr2, the relay coil is activated to close the contact point to turn on turn signal light.
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When the relay contact points is closed, the emitter side voltage of Tr1 drops to turn off Tr1. However, because C2 changing current flows through
D2, C1, R1, and the ground, Tr2 keeps "ON" condition.
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When C1, is fully charged, no electricity flows from C2, causing Tr2 to turn off and the relay contact point opens to turn off the light.
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When the relay contact point opens, the emitter side voltage of Tr1 rises to turn on Tr1, and the closed circuit consisting of R4, the switch, the
light, the ground, power, R5 and Tr1 is formed to discharge C1. At this time the light does not illuminate due to much resistance of R4.
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When C1 finishes discharging electricity, Tr1 turns on, and the relay contact point closes to turn on the light.
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By repeating the above operation, "LH" (or "RH") of the turn signal light and the turn signal indicator light keeps blinking.
In case of disconnection of one light
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When one of the turn signal lights is disconnected, Tr1 does not turn off completely even if the contact point of the relay closes because the whole
resistance of the light circuit increases.
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Therefore, C1 completes charging in shorter time than normal time and illuminating time of the light becomes short because collector current
flows into Tr1 a little.
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Though the contact point of the relay opens and C1 starts discharging electricity, the discharging time becomes shorter than normal because the
charging voltage is low.
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Due to the above actuation, the light repeats blinking in faster cycle than at normal.
