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Wire a universal wiper switch by connecting B to power or ground, L to low speed, H to high speed, and P to park when supported.
For the full breakdown, see our best Universal Windshield Wiper Switch guide.
Figuring out how to wire a universal wiper switch starts with one question: is your wiper motor ground-activated or battery-activated? That answer decides what connects to terminal B, the terminal most people assume is power.
Does Your Motor Use Ground-Activated or Battery-Activated Switching?
Motor type is the whole game. A ground-activated motor switches the ground side of the circuit, so the switch’s B terminal goes to a good chassis ground. A battery-activated motor switches the power side, so B connects to ignition-fed 12 volts instead.
American Autowire’s universal wiper switch instructions cover both setups and make the same warning: never assume B means power. On a ground-activated motor, B is ground. On a battery-activated motor, B is the 12V feed.
Motor type matters because a switch is only a set of contacts. Ground-activated systems switch the ground path, and battery-activated systems switch the power path. B is the terminal that completes whichever side the motor uses. Put B on the wrong side, and the circuit cannot work properly.
What Do B, L, H, and P Mean on a Universal Wiper Switch?
The letters are consistent: B is the common leg, L drives low speed, H drives high speed, and P handles the park function when the motor has one.
Summit Racing’s 4 PIN WIPER SWITCH instructions describe a three-position OFF/LOW/HIGH switch with Accessory Power (+), ground, and separate high and low outputs. Their 4-pin version uses red for 12V accessory power, green for high, yellow for low, and white for park. The white park wire is used with the motor harness when a park connection is present.
Wire colors are a starting point, not a guarantee. Different harnesses may run different colors, so confirm each terminal against the switch’s printed labels or a multimeter before you crimp anything. Summit’s sheet is written for Keep It Clean Wiring Systems and generic harnesses, which means the terminal assignments are meant to adapt rather than match a single vehicle.
Park behavior varies by motor. Some motors expose a dedicated park terminal. Others handle self-parking through a switched earth connection that keeps the motor running until the blades reach rest. The official instructions treat P as optional for a reason: only wire it when the motor actually supports the function.
The table below summarizes where each terminal goes in both wiring styles.
| Terminal | Ground-Activated Motor | Battery-Activated Motor |
|---|---|---|
| B | Chassis ground | Ignition-fed 12V power |
| L | Low-speed wire or terminal | Low-speed wire or terminal |
| H | High-speed wire or terminal | High-speed wire or terminal |
| P | Park terminal only if equipped; connects to the motor’s switched earth | Park terminal only if equipped; connects to the motor’s switched earth |
Universal Wiper Switch Wiring Steps
Once you know the motor type, the hookup is short. Work through this sequence, then test before final assembly.
- Identify the motor type. Ground-activated means B goes to chassis ground; battery-activated means B goes to ignition-fed 12V.
- Connect L to the motor’s low-speed