Trailer Wire Connection

[Davpmars]

Hey Guys,

I just bought my first boat and I'm stoked! However, I'm trying to get a few things figured out.

The trailer has a flat 5 pin connection. I have an adapter that goes from the 5 pin flat plug on the trailer to the 7 pin round plug on my vehicle. I noticed that the trailer brakes were not working and the blinkers (and brake lights) were not working but the lights on the trailer light up real bright.

I took the connector off to look at the round 7 pin adapter and I noticed that 2 of the metal pins are missing. I thought that I would simply have to buy the right connector but while looking on Amazon, they all look they same. They are all missing those 2 metal connections.

What am I missing here?

(Also, I did search for other threads about this issue and I couldn't find anything easily)

[zabooda]

The two pins you are missing are not part of the five pin connector and that is a 12 volt hot pin and electric brake pin. Get a voltmeter and verify your seven connectors are wired correctly (schematic on line) and then check the trailer five pin. I would say one connector or the other is miswired. Some people will wire a connector to match something that is not wired correctly but in this case two wrongs doesn't make a right and rewiring is in order.

[sivs1]

depending on your tow vehicle you could have blown fuses. I know with my Sierra, ages ago all the lights worked except brakes and blinkers. Truck had separate fuses to control trailer lights and brake lights. replaced fuses and worked fine.

[Davpmars]

depending on your tow vehicle you could have blown fuses. I know with my Sierra, ages ago all the lights worked except brakes and blinkers. Truck had separate fuses to control trailer lights and brake lights. replaced fuses and worked fine.

Interesting, my tow vehicle is a 2007 Chevrolet Suburban.

I'll be checking my fuses this evening.

Do you know if there is a fuse box under the dash or if I will find everything in the big fuse box under the hood?


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[kaneboats]

We had an Envoy/Trailblazer a few years back that had a fuse box under the middle seat. Sure enough there was a blown fuse in that box. Might want to look for a Youtube video on trailer lights and your model of truck.

[sivs1]

If I remember right the GMC had a fuse box on the side of the dash on the drivers side. it was a 2005 and am not sure if they moved things around with the redesign. Hoping the fuse is your issue and not something else.

[That Guy]

Sorry to hear of your troubles. Wiring issues are never fun. I chased them on a brand new truck and boat a couple years back, ended up selling both without ever figuring it out!

My .02 though....buy a tester first and check the connections on both the truck and trailer. It's only $5-$10 and could possibly save you from spending hours tearing stuff apart for no reason. Hope you get it figured out!

[trayson]

Yeah, you can accomplish a lot with a test light and maybe a couple jumper wires.

As mentioned, there's only 5 wires on your trailer. Turn left, turn right, running lights, reverse, ground. So you can test these out. (turn left and turn right at the same time would be Brake I believe).

I suspect that the 7 round to the flat 5 adapter is your problem. I've seen reference to the idea that some vehicle manufacturers will have different configurations for their 7 round patters. so if you have a different adapter than is correct for your tow rig, that will cause you issues.