Troubleshooting a Wiring Connection that Caused the Vehicle Flasher Relay to Blow on a 1996 Tacoma

Question:

My 1996 Toyota Tacoma 4x4 4cyl. pickup truck had a trailer wiring harness kit installed on it when I purchased the truck. The wires were ran to each tail light assembly, but not plugged in. I decided to use a utility trailer so I unhooked the tail light assembly in each side and plugged in the trailer wires, I also plugged in the main connector near the hitch. Without plugging into the trailer, I turned my lights on my truck and noticed that my left and right rear blinkers were not working. I then completely unhooked the trailer wiring harness main connector as well as unhooked the connectors from the tail lights and plugged the factory connectors back to the tail lights. After doing this, I turned my signal lights on and both sides were still not working. I also noticed that my emergency flashers were not working either. I changed the flasher relay and now my turn signals and flasher lights are working properly. I noticed that where my ground wire is connected to metal on my truck it is very rusty. Could that possibly be the reason for my flasher relay to blow when I plugged in the trailer main connector and connectors to my tail lights or could it be something else? Thanks

asked by: Timothy Y

Expert Reply:

Sounds like your wiring harness caused your relay to blow.

First thing I would recommend would be to inspect your harness for shorts, it's most likely the turn signal wires.

Your Tacoma has separate wiring, which means that your brake and turn signals are sent along separate wires, and you will need a converter for them to function properly. Without knowing what harness was installed it would be hard to tell if it was the right one, but since it plugged in it likely is. The aftermarket harness should have a black box that is typically mounted within the body of the vehicle behind the drivers tail light. I have linked you to a page that shows all the aftermarket wiring harnesses for you to see the different options. If your current harness doesn't have this, this could be your issue. It could also be that the converter is bad on the unit, which it could just need to be replaced.

The dirty ground is another possible culprit to the lights not functioning properly but the bad relay leads me to believe your harness has a short or doesn't have or has a bad converter. I would relocate the ground to a clean secure metal surface as well as checking the connector at the back of the vehicle for any corrosion too.

If you find you need a new wiring harness, I recommend the # 118379 because of its high popularity amongst customers with your vehicle. I have linked it to this page for your convenience.

expert reply by: Jackie C