
If power is applied accross pins 85 (-ve)and 86 (+ve) then the relay will energise
The relay pictured on the left above is in its natural (unenergised position) so if power were applied to 30 it would go to 87 (ie the indicator)
Now look at the right hand picture this relay is energised so the power is going to 87a (the brake light)
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To make this work in a vehicle
for left side of vehicle Connect as follows
30 is connected to the vehicles Combined Brake indicator wire for left side
85 (-ve, negative permenant connection)
86 goes to pin 30 on the relay on the right side of the car
87 goes to indicator
87a Goes to Left side brake light
Logically if power is applied to 30 alone it will exit the unergised relay at pin 87 and light the indicator/blinker.
If power is applied to 30 BUT also to pin 86 (this picks up power from right side which will only be there if the vehicle is braking) then the relay energises and the brake light is lit
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for right side of vehicle Connect as follows
30 is connected to the vehicles Combined Brake indicator wire for right side
85 (-ve, negative permenant connection)
86 goes to pin 30 on the relay on the left side of the car
87 goes to indicator
87a Goes to right side brake light
Logically if power is applied to 30 alone it will exit the unergised relay at pin 87 and light the indicator/blinker.
If power is applied to 30 BUT also to pin 86 (this picks up power from left side which will only be there if the vehicle is braking) then the relay energises and the brake light is lit.
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