Trailer Ground Wire Gets Hot and Smokes when Connected to Dodge Truck

Updated 06/17/2013 | Published 06/15/2013

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Adapter 7-Pole to 4-Pole and 5-Pole

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$32.36

Hook Probe Circuit Tester

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$13.33

Question:

Whenever I hook up the ground wire to trailer its gets hot and starts to smoke,also no left side trailer running lights or turn signal,using a 4 prong plug,do I need a 5 prong? Haulmark trailer dodge truck 7 to 4 pin connector.

asked by: Ric..

Expert Reply:

It sounds like either that is not the ground wire or there is a short to ground somewhere that you will need to track down. First, on the trailer, the one covered pin is the ground so make sure that is the wire you are attaching to a clean and corrosion free bare metal surface on the frame. A bad ground would also explain the lights no working.

If the 7-Way on your truck is wired differently than standard, that could be a problem too. I have included a link to our FAQ on trailer wiring that shows the standard pin out for various types of trailer connectors. Use a circuit tester like # PTW2993 to test the functions of your 7-Way to make sure they match.

A trailer 4-Way will be ground, then running lights, then left turn/brake lights, and then right turn/brake lights. Also check the trailer and vehicle connectors for dirt and corrosion. If you plug in the adapter and the output side, whether it's the 4-Way or the 5-Way, is not correct then there is an issue inside the adapter, and it will need to be replaced.

Once the ground stops getting hot and smoking you can check the grounds for the lights. They should be attached to clean and corrosion free bare metal surfaces. If the trailer has an aluminum frame, tilt bed, or folding tongue then it will help to run jumper grounds from the lights to the main trailer connector ground.

expert reply by: Michael H