Testing a wiper motor
and the wiring for the three speed switch
If you look really close at the switch there are identification letters stamped in near each connection. They are sometimes hard to make out
B is for Battery - This is the 12volts coming from the ignition to power everything. It is powered with the key in ACC or ON position.
B/U is for BackUp. - 12v comes in through B goes through a circuit breaker inside the switch and goes out B/U to the switch for the back up lights. (No idea why they ran power for those lights through the wiper switch, but there it is! image)
W is for Washer - When you push in the button, 12v from B goes out through W through the bulkhead connector to the washer pump.
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Now the other 4 are a little more complicated. They all go from the switch through a separate plug at the bulkhead to the wiper motor.
A should be a black & white wire. With the switch in the off position, it is connected internally to F2. With the switch in any of the on postions it is connected to B and provides 12v+ to the wiper motor.
P is for Park - this should be a dark blue wire. With the switch in the off position it should be connected to B and provide 12v to the wiper motor (once the wipers reverse their cycle and park, a switch inside the motor itself shuts off the power there) With the switch in any of the on positions P isn't connected to anything.
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F1 and F2 provide power to a shunt field in the motor. The amount of power going through this shunt field is what controls the speed the wiper motor spins at.
F2 should be a yellow wire. In the off position F2 is connected internally to A. In any of the on positions F2 is connected to the metal casing of the wiper switch. This provides a ground connection through the dash.
F1 should be a red wire. In the off position F1 is connected to the metal casing of the switch. In the on positions F1 is connected to A & B, but with a variable resistor in the circuit. At the slowest wiper speed there is no resistance, so F1 gets the full 12v and sends it to the shunt field in the wiper motor. At the fastest speed it looks like there is about 25 ohms of resistance between F1 and (A&B) so the voltage going to the field shunt is less than 12v.
and the wiring for the three speed switch
If you look really close at the switch there are identification letters stamped in near each connection. They are sometimes hard to make out
B is for Battery - This is the 12volts coming from the ignition to power everything. It is powered with the key in ACC or ON position.
B/U is for BackUp. - 12v comes in through B goes through a circuit breaker inside the switch and goes out B/U to the switch for the back up lights. (No idea why they ran power for those lights through the wiper switch, but there it is! image)
W is for Washer - When you push in the button, 12v from B goes out through W through the bulkhead connector to the washer pump.
--------------------------------
Now the other 4 are a little more complicated. They all go from the switch through a separate plug at the bulkhead to the wiper motor.
A should be a black & white wire. With the switch in the off position, it is connected internally to F2. With the switch in any of the on postions it is connected to B and provides 12v+ to the wiper motor.
P is for Park - this should be a dark blue wire. With the switch in the off position it should be connected to B and provide 12v to the wiper motor (once the wipers reverse their cycle and park, a switch inside the motor itself shuts off the power there) With the switch in any of the on positions P isn't connected to anything.
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F1 and F2 provide power to a shunt field in the motor. The amount of power going through this shunt field is what controls the speed the wiper motor spins at.
F2 should be a yellow wire. In the off position F2 is connected internally to A. In any of the on positions F2 is connected to the metal casing of the wiper switch. This provides a ground connection through the dash.
F1 should be a red wire. In the off position F1 is connected to the metal casing of the switch. In the on positions F1 is connected to A & B, but with a variable resistor in the circuit. At the slowest wiper speed there is no resistance, so F1 gets the full 12v and sends it to the shunt field in the wiper motor. At the fastest speed it looks like there is about 25 ohms of resistance between F1 and (A&B) so the voltage going to the field shunt is less than 12v.