Troubleshooting Converter in Tow Ready Custom Fit Vehicle Wiring, # 118412 on 2008 Toyota RAV4

Question:

I have installed three different trailer wiring modules on my 2008 Rav4 Sport with I4 engine. Power is connected to the battery. After installation they work fine. A month goes by and then nothing works. I only tow a trailer occasionally, but this has happened three times. It doesnt seem to happen when I am towing, but when the wiring is not being used. do you know why this is happeneing? I have tried two different harness manufacturers. Thanks!

asked by: Dan G

Expert Reply:

The first thing I would check is the fuse that came with the Tow Ready Custom Fit Vehicle Wiring, part # 118412. If it is not inserted all of the way or is blown, the converter will not work. Make sure the power wire for the converter is attached to the positive battery terminal via the in line fuse holder and fuse. No other 12 volt connection should be used. Make sure the white ground wire is attached to a bare metal surface.

If the fuse is blown you will want to check the trailer for shorts and to make sure that the trailer does not have any extra lighting that might cause the fuse to blow.

On the 2008 Toyota RAV4, there are 2 sets of connectors behind the taillights. Connect the T-one harness to those that are closer to the vehicle taillights. I am including a link to the installation instructions on the wiring harness.

With everything installed correctly, you can test the wiring harness to determine if it is malfunctioning. Using a circuit tester, part # PTW2993, test the wires going into the converter. If the signals are correct going in, then you can move on. If they are not correct, then there is a wiring problem ahead of the converter.

Next check the wires coming out of the converter. If the functions are correct going in but not correct coming out of the converter, then something is wrong with the converter, and it will need to be replaced. If the signals are correct going in and coming out, then something is wrong with the trailer wiring.

I am including a link to a video that will show this wiring harness being installed on a 2008 RAV4. This video might help you verify that everything was installed correctly.