No Trailer Running Lights

Question:

I have a 2014 Toyota Tundra Platinum edition. I have the factory 7 plug and 4 plug harness, which came w truck new. I have brake, stop and turn signal power, but no running lights. Took to Marine and they say not trailer as they have all during test. What is issue?

asked by: Mary K

Expert Reply:

asThe first thing to do is take a look at the owner's manual of your '14 Tundra to locate any trailer fuses or relays and ensure they are all there and in working order. If they are, in order to determine the specific problem you will need to purchase a circuit tester if you do not have one - the very handy Cordless Circuit Tester # PTW2979 would be my strong recommendation due to how easy it is to use - and test the connector on your vehicle after disconnecting it from your trailer. Check the wiring going into your harness from your tail lights to see if those wires are carrying the correct signals, if not then the issue is with the vehicle wiring, which is likely since you said it is not the trailer.

You will also want to check both your vehicle and trailer connectors for corrosion, which can be green or white in color. A build-up of corrosion can interfere with the signals getting through the connectors so if it is present you are going to need to either replace the plug or clean the corrosion. You'll also need to make sure your grounds are attached to bare metal surfaces and free of any paint, dirt or corrosion.

I have added links to a pair of help articles on trailer wiring, including a troubleshooting guide which I highly recommend taking a look at.

expert reply by: Kyle S