Trailer App

zelmo · June 3, 2020

I took another trip today. Hoping that the issue would disappear now that Onstar was no longer active I reset a trip log on the truck and the trailer mileage in the app to zero. I watched closely and they were in sync as I started the trip.

After a while I got into some traffic and I needed to pay attention to driving. When I was out of that I checked the mileage and found that the trailer mileage was 20 miles less than the truck. I don’t know if it had just stopped tracking for a while or if it had pealed off 20 miles. I paid attention for the rest of the trip and it was tracking. When I got to the ramp it was still off by that same 20 miles.

I then parked and turned the truck off while I got ready to launch the boat. When I started the truck I checked the mileage on the app. It had changed and showed 4 miles more than the truck.

When I was driving home that 4 mile difference stayed the same for the whole trip, meaning it worked correctly. Since I only intended to use this for tracking maintenance needs I will just live with it. I will mention it to the dealer when I take the truck in for service but I doubt they will figure anything out.

GMC-AT · June 3, 2020

On 4/7/2020 at 10:06 AM, zelmo said:

While I had looked at the manual and read some of the info on the trailer app I should have studied it better. I went back and did that. Here is the section on the security feature:

Security Alert

A security alert can be set if a trailer is connected and the alert is enabled. When the trailer is disconnected and the vehicle is off, an alarm will sound. Touch Security Alert in Settings to view the Security Alert settings page. These alerts are based on the Trailer Profile, so the settings for each Trailer Profile must be turned on or off. Touch a profile to view more information or adjust the setting for that profile. This setting will be off by default for each Trailer Profile, including the Guest Trailer Profile. A smartphone will receive a notification that the trailer related to the selected Trailer Profile is disconnected from the vehicle, if the setting is on for the active Trailer Profile, the vehicle has an OnStar or connected service plan and the smartphone number has been added to the account for this notification.

If the setting is turned off for a given Trailer Profile, the smartphone will not receive this security notification even if the Trailer Profile is active.

Too bad you need Onstar for the smartphone feature to work.

Guys - I noticed my trailer lights will blink when the truck is turned off and just sitting there with boat hooked up. I thought something was wrong....but I guess not. So to be clear.. if I unhook my trailer while the truck is locked.. the truck alarm will go off? Or do I need the onstar stuff for it to work?

Jav_eee · June 3, 2020

Guys - I noticed my trailer lights will blink when the truck is turned off and just sitting there with boat hooked up. I thought something was wrong....but I guess not. So to be clear.. if I unhook my trailer while the truck is locked.. the truck alarm will go off? Or do I need the onstar stuff for it to work?

It’s supposed to honk or something if the trailer is disconnected.

Sent from my iPhone using Tapatalk Pro

zelmo · June 3, 2020

11 minutes ago, GMC-AT said:

Or do I need the onstar stuff for it to work?

It is my understanding that the honk will work without Onstar but in order to receive a notification on your phone you do need Onstar.

GMC-AT · June 3, 2020

ok, great... that's I all need is a honk, my boat and trailer are always parked close to me. I'll try it out soon and see if works. I always thought the light flash was a back feed issue or something....

zelmo · June 3, 2020

I have been meaning to experiment with this but haven't gotten around to it. Let us know how it works.

AlaskaErik · June 3, 2020

7 hours ago, GMC-AT said:

ok, great... that's I all need is a honk, my boat and trailer are always parked close to me. I'll try it out soon and see if works. I always thought the light flash was a back feed issue or something....

You do need to activate the feature for it to honk. Default is deactivated..

Greyhound6.2 · June 4, 2020

I tried the honk feature after i turned it on, and locked the truck it did not honk when i disconnected the trailer.

AlaskaErik · June 4, 2020

4 hours ago, Greyhound6.2 said:

I tried the honk feature after i turned it on, and locked the truck it did not honk when i disconnected the trailer.

It won't work if you have your fob in your pocket. The fob needs to be out of range, otherwise the truck thinks you're the one disconnecting the trailer and won't sound the alarm.

Brian Autwell · June 9, 2020

On 5/28/2020 at 11:44 AM, zelmo said:

Well I don't know what is going on.

I took another trip with the starting mileage at 49. This time the destination was 64 miles away. That means that when I got there the mileage should have been 113. The app said the mileage was 119.

While that was off it wasn't the worst. When I got in the truck to go home the mileage had changed to 161. As I traveled the mileage ticked up and was at 210 when I got home. It should have said 177 (or 183 if you add 64 to 119.)

Any theories? Nothing adds up on this trip.

Wife pointed this issue out to me this weekend. Picked up a new travel trailer and moved it from dealership to storage in about 33 miles. The app showed I put on 96 miles. New profile and all. I’d be interested in hearing what others have noticed.

Greyhound6.2 · June 10, 2020

I had a trailer tire temp warning pop up on the cluster after being stopped for a lunch pit stop at 139 degrees but when i opened the app it showed all 4 tired under 130 degrees. plus i have seen the tire temps up to 145 without a warning pop up. also curious what temp the sensors are supposed to alert you at.

AlaskaErik · June 10, 2020

2 hours ago, Greyhound6.2 said:

I had a trailer tire temp warning pop up on the cluster after being stopped for a lunch pit stop at 139 degrees but when i opened the app it showed all 4 tired under 130 degrees. plus i have seen the tire temps up to 145 without a warning pop up. also curious what temp the sensors are supposed to alert you at.

I just towed my trailer 300 miles yesterday and temps were in the low to mid 70s. Pressure went from 65 psi cold to upper 60s. Unfortunately, I haven't seen anything indicating when over temp or underinflation warnings pop up.

AlaskaErik · June 10, 2020

3 hours ago, Brian Autwell said:

Wife pointed this issue out to me this weekend. Picked up a new travel trailer and moved it from dealership to storage in about 33 miles. The app showed I put on 96 miles. New profile and all. I’d be interested in hearing what others have noticed.

Mine seems to be pretty accurate.

lschafroth · July 18, 2025

I have a 2020 GMC Sierra 2500HD AT4 with the premium package. I have a Springdale camper with the TPMS sensors. Everything works but every once in a while, it says no trailer connected. The default brake setting of 5 is set. I normally have it at 6. Everything works, lights, brakes etc. If I load the Trailering app and manually select the profile for this camper it loads everything normally. Not sure if there is an updated version of the app to fix these bugs or what. I will check that later today.