Running Lights Blinking When Trailers Are Connected Without Turning Lights on in Vehicle

Question:

When I plugged my toe to the trailer all side lights are blinking just after connecting without turn on any switch in the cabin And no other lights break, right and left signal lights working. Additional information via email- have tried other trucks with same result

asked by: Sriram

Expert Reply:

Thank you for the additional information via email. Since this issue is occurring on multiple trailers connected to the same vehicle, it would be most likely that the issue is caused by the wiring or harness on your tow vehicle. I would first check the 7 way connector for any rust, corrosion or dirt; clean off or replace as necessary. You'll next want to check the ground connection on your 7 way connector to make sure that it is secured firmly to a rust, paint and debris free surface on the frame of your vehicle- this short could be causing the malfunction you're seeing.

If the ground connection is secured, you'll next want to use a circuit tester like the # PTW2992 and check the circuits on your 7 way connector- I've attached a picture of the 7 way connector diagrams that you can use as a reference. You'll want to make sure that each of the circuits are passing 12v of power through them only when they are engaged; if any of the circuits are engaged without that circuit being activated, your short is going to be on that wire. If you find a shorted wire, you'll want to trace back that wire, checking for damage along the way; you'll want to replace and damaged wires as you go.

If you can run through these troubleshooting steps and your issue has still has not been resolved, let me know and I can continue to assist you with some other steps to look at.

expert reply by: Erik B