What do the three wires of the rear wiper motor mean?
2 Answers
It means one is the positive power supply, one is the ground, and the other is the wiper positioning signal. The functions of the three wires in the wiper motor rotor: One is the common terminal A, the one with a small resistance to A is the high-speed terminal B, and the one with a large resistance to A is the low-speed terminal C. Usually, the resistance between B and C is the smallest (or sometimes the largest). The other two are the return identification wires, which internally act as a switch (in the form of a slider or camshaft) and only disconnect when the wiper blade reaches the lowest point. Measurement method for the three wires of the wiper motor: One is the positive wire, one is the ground wire, and the other is the signal wire. Measure the resistance against the motor casing respectively. The highest resistance indicates slow speed, the lowest indicates fast speed, and the other indicates medium speed. No resistance or infinite resistance indicates a fault.
When I was repairing a car, I encountered the three wires of the rear wiper motor: the power wire, ground wire, and control wire. The power wire is a +12V voltage source connected from the battery or fuse box, specifically to power the wiper motor. The ground wire connects to the metal part of the car body, serving to complete the circuit and allow current to flow. The control wire is crucial—it connects to the wiper switch to command the motor's actions, such as making the wiper sweep back and forth or change speeds. These three wires are indispensable. If the power is cut off or the fuse blows, the motor won’t turn. A loose ground wire may cause circuit instability, and issues with the control signal can make the wiper move erratically or fail to start. For troubleshooting, you can use a multimeter to measure voltage: the power wire should show 12V to be normal, the ground wire must have a solid connection, and the control wire should show changes when the switch is toggled. Safety should never be overlooked, especially in rainy conditions—a malfunctioning rear wiper can obstruct the view of vehicles behind, increasing the risk of accidents. It’s recommended to regularly check the wiring harness for aging or cracks and address any issues early to avoid trouble on the road.
