7 Pin Connector From Truck to Trailer

jerryjay11 wrote:
Since I have been using electrical contact grease on my connectors I haven't had any problems with error messages. It helps prevent corrosion and aids the conductivity of the pins.

To add to my post above...

We (GM shop) tried the grease with our GMC due to water in the 7pin, no luck, no change. Connectors were not dirty as the truck was only 6 months old and had seen one or two dirt roads in the time we had it. And to boot, had a brand new 7 pin put on and it still did it. I would get the error and have zero trailer brakes yet all the trailer lights worked fine.

Trailer was checked out and all worked fine. Truck was checked out and all worked fine.

Wonder if there's something in the e-brake that frustrates the GM computers at hookup (theory at best)? Hook it up before power, zero issues.

Adding Dielectric grease to dirty contacts does nothing to clean those contacts. Spray some contact cleaner into your trailer plug contacts. You could even go so far as to run an emery board in and out of each contact. Then add your grease to prevent future corrosion.

Since I have been using electrical contact grease on my connectors I haven't had any problems with error messages. It helps prevent corrosion and aids the conductivity of the pins.

get to a trailer place and have them look at the issue...they are the ones who should be able to give you an answer.

I'm on my second GM truck in 2 years. The first, a 2018 1500 sierra did the same thing. Had the 7pin replaced under warranty because it seemed to be full of water after every rain, wash, etc. Still gave the error after replacement so I too hought it was the trailer. It was not.

What I found was this. My theory: For some reason on these new GM trucks, we (I had to any way) have to set up the trailer emergency brake plug FIRST before plugging in the 7pin (needed to be dead power to trailer). Putting power to my trailer first and then connecting the trailer brake was giving me the error. No idea why. But when I set up the trailer e-brake first, power second - Never had another error. Give it a try.

After all that though, it truly could be the trailer. My 2 cents.

Cardinals wrote:
I have had an issue that happened now on two separate Silverado 2500's. When I would plug the trailer plug into the 7 pin receiver on the truck I would get an error message saying "Check Trailer Wiring". I had thought the connection was loose as the lights, breaks, etc worked.

In May I purchased a 2019 Chevy Silverado and now get the exact same message. The trailer was in for repair work that last two days and they checked the plug and said it was fine.

On my way to truck dealer now to see if they have a suggestion...

Thanks for any input.

ps: I did used diaelectric on it but to no avail.

Just for curiosity, is the truck running when you plug or unplug it? My Ram will throw an error if I leave the truck running and then unplug the trailer. However, if I shut the engine off and then restart it, the error will have cleared.

Bill J., Lexington, KY

on a whim I did a quick internet search about this. The issue seems to be mostly related to either a poor ground connection or poor brake wire connection.
If it was my truck I would look at the trailer plug and see if it's possible to remove some screws and open it up. If so then pull the screws and slide the outer shell off the trailer plug exposing the wiring connections. Inspect and tighten each wiring connection making sure that the bare wire is fully trapped under the end of the screw. Then put the plug back together.

If all is tight then try cleaning the ground connection on the trailer to the plug on the trailer. Or clip a standard jumper cable (for jump starting vehicles) from a ground on the trailer to a ground on the truck. Bungee or tape the jumper cable up out of harms way and go for a drive.

If it still fails you'll want to inspect the brake wiring from the trailer plug all the way back to each individual wheel. Look for exposed wiring or places where the wire might be pulled tight across a corner and rubbed through.

If all this fails to resolve the issue then I would by a $10 spool of wire at Home Depot and cut every brake wire behind the wheel. Then run a temporary wire from the plug to one wheel at a time and go for a careful drive. Keep swapping and testing until you can isolate which wheel is tripping the message.

Here Chevy has a bulletin about it that basically says check the trailer wiring.
Link

A common place the brake wiring shorts to ground is where the wire goes into the axle tube. Just pull the wire a bit and see if the wire insulation is chafed exposing the wire.

I just got my 2016 2500 this Summer and it was doing the same thing on the way back from our first trip. It was pulling and stopping fine but the dinging every five minutes was annoying. I cleaned out the truck side of the plug really good and I also used something to bend in the connectors on the trailer side a little. They were pretty spread out from years of use. Things were fine from then on. I did the get message on our last trip, but it only lasted for a second and I never saw it again. It was after I had went over a bump, so I am wondering if that might have caused it. There are lots of threads about this similar issue on the web though if you do a Google search.

If it's happened on two different trucks, I'd say it points to the trailer wiring. An intermittent short can be a bear to nail down. Sorry to hear. Hope they get it sorted out for you.

As a side note, my buddy has a boat and we've found that the connectors in the plug for both the truck and the pigtail can get moved around and will sometimes make intermittent contact, so a little corrosion combined with being a little pushed out of alignment and we'll see issues with the brake lights, electric winch, etc.