Testing a 3-speed wiper system
The 3 speed wiper system controls the speed by use of a resister in the switch, not in the motor. The switch also reverses the current to the motor in the "off" position, which causes the motor to seek the "home" position. There is also a circuit breaker built into the switch to protect the circuitry.
Testing the switch
There is a test for the switch that can be done with a continuity tester or an ohmeter. To do this test, on the back of the switch, the terminals are marked with an"A", "B", "B/U", "F1", "F2", "P" and "R1". In the tests, "Ground" is the switch casing.
While in the "Off" position there should be continuity between
B to B/U
B/U to P
A to F2
F1 to Ground
"LOW"
B to B/U
B/U to A
A to F1
F2 to ground
P - open
"Medium"
B to B/U
B/U to A
A to R1
F2 to ground
P - open
"HIGH"
B to B/U
B/U to A
F2 to ground
P - open
Testing the motor
The motor only has two speeds, high and low. The medium speed is a variable speed, which is configured by the switch varying the voltage to the motor.
"Low"
Connect the motor housing and the green wire to ground
Bridge the brown and red wires
Connect either the brown or red wires to 12v
Motor should turn slowly
"High"
Conect the motor housing and the green wire to ground
Connect the brown wire to 12v
Motor should turn fast
"Park"
Connect the motor housing and the red wire to ground
Bridge the brown and green wires
Connect the blue wire to 12v
Motor should turn backward, then stop in park position