Vehicle in question is a 2007 Toyota Rav4 Limited with the 3.5l V6 and has the factory tow package. I have a trailer harness in which the green pole, aka the right/passenger side turn signal, is staying at 12+V when the lights are on, and the voltage is not pulsing like it should be. The other poles are working correctly. I am trying to test the voltage coming out of the taillight harness/plug behind the rear passenger side interior panel, but I am scared of shorting something out.

I was thinking about putting the positive multimeter lead on either the red or green wire coming off the taillight trailer harness adapter, and putting the negative multimeter lead on the frame. Well first off, I'm not sure which is for the turn, the red or the green. Secondly, I am wondering if any of the other 4 white wires on the trailer harness adapter are a ground and if the negative multimeter lead should go on one of those instead.

Any help would be much appreciated. I have tried finding a wire diagram for this circuit, but I have had a hard time figuring out exactly what I am looking at in some of them. I can't seem to find one that correlates exactly to the circuit I am trying to troubleshoot. I saw a post from years ago on here mention this site for diagrams, https://www.eautorepair.net , but they charge money. Are there no free options floating around? Also I figure taillight hookups are fairly similar and that one of y'all would probably know which lead is which.

Here are some pictures of the taillight to trailer harness/plug for the right side in question.

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  • Many wiring diagrams for the 4 or 7 pin connector at the back on the internet, although some are looking at the connector on the car and some looking at the connector on the trailer (sigh). So be careful with diagrams you find unless they are clear.
    – Jon Custer
    Commented May 5, 2021 at 22:21
  • M 2004 Nissan had a relay under the hood that isolated the truck system from any problem in the trailer harness. I suspect your truck has similar protection. Commented Jan 29, 2022 at 22:06

1 Answer 1

  1. You wont short anything out

  2. Way to do this is exactly like you said: Put the positive multimeter lead into the plug where the wire ends. Then put the negative to the chassis, non painted area.

  3. Then hit the turn signal and see if it start fluctuating the voltage. If it doesnt but the turn signal is blinking, go to a different wire in the plug. one of them will.

again, you wont short anything out.

  • If the multimeter is set to "current mode" then he will short something. Since OP isn't well versed in electricity, Id suggest to mention the correct setting of the multimeter
    – Martin
    Commented May 4, 2021 at 19:39
  • Youd want it in 12v so that it reads the voltage the blinker is putting through. Commented May 4, 2021 at 19:42

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