I bought a 12 volts wiper motor and am trying to connect it to a 12 volts DC 4.2 amps power supply. There are 4 terminals on the motor. I'm confused regarding which terminals that I should connect the positive and negative ends of the power supply to. When I connect the positive and negative wires from the supply to the two leads on top side of motor terminal (circled in red in the first picture), the motor turns very slowly and I can observe the power supply LED flashing which indicates a voltage drop. Can anyone please help me with the connections ?

wires of wiper motor motor

  • \$\begingroup\$ Datasheet link, (lucas-tvs.com/pdf/2sw60.pdf) \$\endgroup\$ – bobdxcool Feb 27 '17 at 15:53
  • \$\begingroup\$ There's a wiring diagram in the datasheet. Unfortunately it's unreadable. But it looks like you may need a beefier supply ... or a car battery ... to supply the motor's starting current. \$\endgroup\$ – Brian Drummond Feb 27 '17 at 16:00
  • \$\begingroup\$ @BrianDrummond Thanks for the suggestion. I wanted to make sure I have wired it properly. Added a video youtu.be/rQwMDVhmZQo showing how slowly the motor turns and drop in power supply voltage. \$\endgroup\$ – bobdxcool Feb 27 '17 at 16:04
  • \$\begingroup\$ From the looks of the horrible datasheet, there looks to be some other thing between the motor and the battery, did you get that too? And a 5A Fuse. \$\endgroup\$ – Tyler Feb 27 '17 at 16:05

It's funny that you bring this topic up because I just dealt with this whole scenario about a week ago when I was diagnosing my niece's windshield wiper motor.

Any modern car is going to have five connections on the motor. One is a ground. There are two wires for positive, one for low speed of the wiper motor and another for high speed. Then, there are two more wires that are used like a switch to determine when the windshield wiper is in "home" position.

But you only have four connections you say? Well, this tells me that the case itself is the ground and that the other four terminals correspond to the other four connections mentioned.

I would measure the resistance between each pin and the case (ground). There should be two pins that measure infinite resistance because they are not connected to ground in any way. These are the two wires that determine when the windshield wiper motor is at the home position.

The other two wires are the high speed and low speed wires. Take your pick and try one and see which one is faster.

Edit: After further looking, it seems that one of the pins IS the ground. This means it doesn't have two speeds or that the home position switch is only one wire.

  • 1
    \$\begingroup\$ And one thing you COULD read in the data sheet is that it has two speeds... \$\endgroup\$ – Brian Drummond Feb 27 '17 at 17:06
  • \$\begingroup\$ @BrianDrummond I managed to find out that the motor chassis is the ground. It looks like the two terminals circled in red (in the initial picture I posted) are for speed control. When I connect positive to the right circled (in the picture I posted initially) blue wired terminal, the motor rotates normally like at 45rpm. But when I connect positive to the left circled (in the picture I posted initially) blue wired terminal, voltage drops and the behavior is exactly same as in this video, youtu.be/rQwMDVhmZQo \$\endgroup\$ – bobdxcool Feb 27 '17 at 18:26
  • \$\begingroup\$ Update: I shorted the top two terminals (circled in red) and motor turns faster than before with only one speed wire connected. I dont quite understand why its turning faster after shorting both the speed (low, high) wires and dint turn normally for one speed wire and turned normally for another speed wire when these were connected individually. here is the video showing the increase in speed, youtube.com/watch?v=JaaZfPIh1x0 \$\endgroup\$ – bobdxcool Feb 27 '17 at 20:12

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