Trailer lights hook up

[nummy]

Hi All

I have a 2003 Chevy Silverado. Where the trailer wiring harness comes down from the body there is a single capped wire that comes out of the harness. Does anyone know what that is for?

Thanks

[sears6341]

The high mount third brake light.

[nummy]

Correct me if I’m wrong, I am talking about a capped off wire coming off of the trailer harness from the truck bed. Not a harness that goes to the cab for a third brake light. Please explain further for me. Thanks Steve

[jstrasser]

It would be used if a truck cap (topper) was installed- those have a CHMSL which needs that connection.

[nummy]

Hi Again

 

I have been searching all of my resources. The wiring harness that I have is a seven wire plug set up, for a heavy duty trailer harness. A friend said that he thought that the capped off (terminated) wire maybe for trailer brakes. Any ideas?

[nummy]

#4jstrasser + Sears6341

 

Just may have it. Thanks. Good call. The truck cap explained the high mount third brake light.

Thanks again

Steve

[jstrasser]

The trailer brake connection is one of the 7 wires in the 7 pin connector.

 

Take the single capped off wire, peel an inch of insulation off the end- hook up a voltmeter to it and a ground. Step on the brake. That will show power. Like I posted, it is for an auxilliary 3rd brake light.