Troubleshooting a Trailer That Does Not Have Working Turn Signals or Brake Lights

Updated 03/21/2017 | Published 03/19/2017

Products Featured in This Question

Hook Probe Circuit Tester

(70)

$12.41

16-14 Gauge Butt Connector - 5 Pack

(33)

$4.24

16 Gauge Primary Wire - Black - Per Foot

(64)

$1.10

Question:

just installed all new tail lights, markers lights and all new wire. Still no turn signals and brake lights. Help please.

asked by: John C

Expert Reply:

Since it sounds like you have totally revamped your trailer, you will want to start out by testing the wiring harness on your tow vehicle. You can do this using a circuit tester like part # PTW2993.

If any of the functions on the wiring harness for your tow vehicle are not working properly then you will want to follow that wiring along the frame of your vehicle to make sure that there are not places that have any corrosion, rust, bent, or exposed wiring. If any of it looks like it needs to be replaced, you can do that using 16 Gauge Wire # 16-1-1 and Butt Connectors # 05731-5. You will also want to check all of the fuses on your tow vehicle as well.

If everything on your tow-vehicle side looks good, then I suggest double-checking all of the work that you already did on your trailer just to make sure that it all still looks good. If you did your own wiring to the harness, make sure that all of the wiring is connected to the correct positions. You can also test the wiring by using a separate battery to see if the lights work with a battery other than your truck's battery.

If all of the wiring looks good and you you have a fully functioning wiring harness on your tow vehicle then unfortunately you will need to take it to a qualified technician who can physically look at it and determine what is wrong.

I have attached links to some demonstration videos and a helpful article for you to review.