Need help....having trouble with power to the trailer harness to my 2004 4 runner. Only allows tail light on Rt side and no turn signals on either side. Test trialer with another vehicle with no problems so the trailer wiring is not the issue. Checked all fuses, none have blown. Taken wiring harness of 4 runner, find no issues. Testing 4 plug I purchased suggests a grounding issue but can not find one. I have no issues until I had to replace my alternator and battery 3 weeks ago. Anyone have an idea what could be the cause? I suspect something needs to reset due to the new battery or alt. Am i missing something?
Trailer light Grounding issue?
- Thread starter mrock
- Start date
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Jerrydog
New member
Time to break out your 12v test light and with a friend operating the vehicle test all teh circuits at the plug in the back of the vehicle. If you find a few not working then trace that back to the fuse block and check the items there, also check the wireing harness plug where it plugs into the trailer plug.
gm350reratliff
New member
Being that only the tail light and only on the right side work makes me believe there is some wiring issues with the trailer. The tail marker (tail light) circuit is the same for both sides. If one side lights the other should as well. Do the lights on the trailer ground to the trailer frame? If so, does the ground wire from the trailer plug go to the frame as well. All clean connections? It sounds like the trailer is trying to ground through the ball (this actually works on some vehicles-not recommended). Which would explain why it works with another vehicle and not the 4runner.
