What to Check When There is No Power to the Right Side Blinker and Brake Light?  

Question:

Helpful Expert Reply:

The white wires will indeed need to be grounded. This should be done with both lights. If this does not get the lights working properly, you will need to use something like the # PTW2993 to test several things.

First, you will need to check the plug on your vehicle to make sure all the ports are working properly. If you have a 7 Way connection, the 3 o'clock position will be the right turn signal and right brake signal. If there is no power, you will need to then check the wire on the back of the plug to see if there is power going into the port. If there is no power, you will need to check the vehicle's towing fuses to make sure they are all good.

If you have a 4 Flat connection, you will want to check the green wire for the right turn signal. Again, if there is no power, you will need to then check the wire on the back of the plug to see if there is power going into the port. If there is no power, you will need to check the vehicle's towing fuses to make sure they are all good.

If your fuses are all good, you will most likely need to replace your wiring harness. The correct one will depend on your vehicle, if you have a 7 Way or 4 Flat, and if the vehicle came pre-wired from the manufacturer.

That covers the vehicle side. If all that checks out, it is something on the trailer that is causing the issue. You will want to check all your ground connections to make sure they have a good clean connection to bare metal, making sure it is not aluminum.

Once all the grounds are checked and or re-grounded, test the lights by plugging securely into the vehicle. If they still aren't working, you probably have a break in one or more wires and will need to follow them to find said break. That being said, you should always start this directly behind the plug that connects to the vehicle. These do go bad over time and are easily replaced. For a replacement on a trailer with a 4 Flat, I suggest going with the Hopkins # HM38134. This features their Easy-Pull design, making it quite a bit easier to disconnect from the vehicle. For a trailer with a 7 Way, the Hopkins # HM20086 has built in test lights to make things easier if this ever happens again.

expert reply by: Lazer S

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