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Left Turn Signal and Brake Lights Do Not Work On Trailer or 4-Way on 2006 Honda Ridgeline


About 4 yrs ago I installed a hidden hitch and wiring harness #118400 on a 2006 Honda ridgeline. It has worked fine until about a month ago. The Lt signal/brake light are not activating and I have tried it on 3 different trailers with the same result. I believe I have traced the problem back to the black module. I have power in those lights wires to the box, but nothing from the box to the trailer connector on the Lt brake/signal wire. Is there a way to by-pass the module or do i just need to replace the entire harness? Is it common for these to fail or short out?


Expert Reply:

You have done all of the correct testing and it does indicate that the converter in harness # 118400 has gone bad and needs to be replaced. There could be any number of reasons for a converter to go bad. It could be a short on the trailer that blew the box, protecting the vehicle wiring like it was designed.

Check the trailer to make sure the grounds are all attached to clean bare metal surfaces. Also make sure that the trailer and vehicle side connectors are free of dirt and corrosion. Check the wiring for any bare wires that might be touching metal.

Four years is a pretty good run for an aftermarket trailer wiring harness on a vehicle without a tow package. There are a lot of things that can negatively impact these types of harnesses like the weather, overloads, and dirty connectors.

Your vehicle has a 3-wire system with separate turn signals and brake lights where as the trailer uses a 2-wire system with combined brake and turn signals. The converter is needed to convert the 3-wire signal to a 2-wire signal so you cannot bypass it.

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Follow up Questions

Dan T.
Where is the convertor box usually located on a 2006 Honda Ridgeline?
Etrailer Expert
Reply from Chris R.

If your Ridgeline is equipped with a factory trailer harness, from what I could find it looks like the converter is mounted behind the left side of the dash inside the cab. I might try and verify this with a local Honda dealer though if you have trouble locating it.

Bob W.
I installed your trailer wiring kit for my 2006 Honda Ridgeline several years ago, worked flawless until recently. The trailer lights work, but the brake and turn signals stopped working. I verified the trailer wiring, all appears to be OK. Any ideas, could the converter box be bad. Is there a troubleshooting guide for the converter box?
Etrailer Expert
Reply from Chris R.

It does sound like you could have a bad converter box. You can test this pretty easily by checking for power on the brake/turn signal wires going INTO the box and testing for power AFTER the box to see if it disappears. If this is the case a new converter would be in order. Otherwise check to make sure the main ground wire is still securely attached to clean, bare metal. A weak ground might cause this type of issue as well.

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