Random “Service Trailer Brake System” warning?

[mistaare]

Got a cap installed today. They ran a wire to the battery to be able to turn on a LED light in the cap. Then tonight “Service Trailer Brake System” warning came on. No other lights came on after I hit ‘dismiss’. Anyone else had a random ‘Service Trailer Brake System’ warning come on? Any chance the cap install is related? 

[davester]

If they cut into the trailer brake wire to provide a brake signal to the cap, it certain could cause that error code.  But that would be a super-common problem for whomever installed the cap, unless this was just a one-off job for them.

[mistaare]

6 hours ago, davester said:

If they cut into the trailer brake wire to provide a brake signal to the cap, it certain could cause that error code.  But that would be a super-common problem for whomever installed the cap, unless this was just a one-off job for them.

Would trailer brakes be effected when I have a trailer attached?

[mistaare]

He claimed he tapped into the 3rd brake light wire (as instructed by ARE). 
 

But I swung by today (to pick up something else) and we tested the trailer plug out let. It had power going to it but nothing else worked? No turn signals, no brakes? 
 

he disconnected the alligator clip, still no brake lights, turn signals etc and he just shrugged his shoulders and said “eh, have the dealer assess the situation”

 

they definitely worked before the cap install, anyone have any ideas on:

-1 where to tap in for cap lights

-2 What might be needed to get my trailer lights working again? 
 

thanks. 

[Ryguy]

Seems like these trucks don’t like any external battery connections, or splicing of the oem wires for anything aftermarket. 
I have Ridged fog lights wired to a separate switch with a relay and I’ve gotten the brake warning lights before too. 

[mistaare]

I went over my buddies and just plugged his trailer in and all the lights worked!?!?

 

so confused. 

[Wbrisett]

On 1/15/2020 at 5:34 PM, mistaare said:

I went over my buddies and just plugged his trailer in and all the lights worked!?!?

 

so confused. 

It sounds like it's random, that is in your original description you mention that it just came on. But what you failed to state is if after clearing it, it came back on. The Canbus system (smart electrical interconnect system) will throw errors if things are not done correctly. As previous posters here have stated, if you ever just cut into a wire for things like power, like the Hulk, the Canbus system will get very angry ... So don't ever do that. In fact, I've been dealing with Canbus on my BMW motorcycles for years and they are a PIA when want to install accessories. In most cases power can't be tapped into, instead you tap into a signal line that indicates power, and it goes into a power distribution box connected directly to the battery. This box has electronics in it as well for the Canbus. If the folks installing the cover tapped into a power line, then it's possible depending on load that the Canbus is throwing the error. Sometimes it will, other times the error isn't present. 

 

I will also state that my 2020 Silverado indicated that my trailer brake was not connected (however, all lights on the trailer functioned properly, just no voltage to the brake system). After checking my trailer and not finding a problem, I then borrowed another trailer and found the same issue. I then took it to the dealer and a bad wheel sensor is actually causing the issue. Again the Canbus strikes back. The error checks are there for safety reasons, but in my opinion they can sometimes prove erroneous. In my case, it wasn't the trailer brake, but another part, but the error caused the truck to no longer produce the voltage needed, for safety reasons, for connecting up a trailer. I think the idea here is that if you get a warning, you won't try to connect a trailer ¯\_(ツ)_/¯ regardless, it's not the proper message, but shows up and suddenly you think you have a trailer issue. So it could be possible that there is something else causing the issues. 

 

By the way if you ever need to check your 7 pin connector, don't spend the money on those 'dumb' testers you can find with 5 LEDs on them. They won't work with the newer trucks. The only tool I've found that works is the IPA-9107A, if you do a youtube search you can find some videos on how it works. 

 

Good luck tracking down the issue! 

[Jeff Lawrence]

I've been getting this Service Trailer Brake System on my dash. Ive seen a lot of Youtube showing it can be a trailer brake relay, a trailer brake module and the trailer brake actuator ( switch at dash) circuit board. All three of these components are an easy fix and fairly inexpensive, but how does one test/ know which one is the culprit. Should I take it to a shop to have it "scanned"? Would like to figure this out , if anybody has experience with this trailer brake electrical problem I would greatly appreciate any ideas.  Jeff

[mistaare]

7 hours ago, Jeff Lawrence said:

I've been getting this Service Trailer Brake System on my dash. Ive seen a lot of Youtube showing it can be a trailer brake relay, a trailer brake module and the trailer brake actuator ( switch at dash) circuit board. All three of these components are an easy fix and fairly inexpensive, but how does one test/ know which one is the culprit. Should I take it to a shop to have it "scanned"? Would like to figure this out , if anybody has experience with this trailer brake electrical problem I would greatly appreciate any ideas.  Jeff

Just curious if you plugged a trailer in to see if it still works. I got that in my DIC once, since then I towed a few times and the lights work. Not sure if the brakes work (that trailer will be in storage til spring). 
 

if it comes on again I will definitely have the dealer look at it though.

[Asmith721]

I just bought and picked up my 2019 RST yesterday 2/24/22 and didn’t have any issues during the test drive and on the way home, drove home in a mild blizzard and this morning I started getting the service trailer brake system message also. 

[Asmith721]

On 2/25/2022 at 8:26 PM, Asmith721 said:

I just bought and picked up my 2019 RST yesterday 2/24/22 and didn’t have any issues during the test drive and on the way home, drove home in a mild blizzard and this morning I started getting the service trailer brake system message also. The truck doesn’t have a cap on it, nor are there any other sort of lights that would have been spliced in or anything. Trucks completely stock. Message comes on everytime I start the truck. 

[wildfan]

I have similar issues with my 2019 LT. Every time I start the truck this past week, with no trailer attached, I get the "service trailer brake system" message. I can dismiss the message and it does not come back during the current drive cycle. If I turn off the vehicle and restart it, the message reappears.  Nothing has been touched or modified from OE. I'm curious if there has been a common repair related to this situation. I talked to the parts counter at a GM dealer, and he indicated they have been replacing a lot of controllers as of late, but didn't know the owner's complaint. Since you can buy a new OE controller for around $10, I'm tempted to throw one in and see what happens prior to paying for diagnostics at the dealer. 

[64BAwagon]

I dont think its a coincidence that the issue arose after the cap installer messed with it. The CHMSL usually has a connector at the rear bumper but depending on the model the plug will require a pin to be added. There were years that had a seperate connector capped off for the CHMSL (early 2000's) and the 2007 and later had to have a wire run to the bottom of the firewall and into a connector on the bottom of the interior firewall. Without knowing what year truck you have its impossible to say. In my opinion this is the cleanest way to power the CHMSL because there is zero slicing into the OEM wiring. you just add a plug to whats already there. When I bought the cap for my 2018 Silverado 1500 I did all my own wiring because I knew my work would be way cleaner than anything they would do for the $75 they wanted to charge me. 

I know some shops will use a "T" adapter in the rear lighting connector near the back bumper. You can also wire a logic circuit into both brake light wires that will give a constant 12v+ if the brakes are applied but not if just one is on as a turn signal. If you can post a pic of the area behind the bumper it may show what they used. 

[Alain 974]

On 23/03/2023 at 18:20, wildfan said:

J'ai des problèmes similaires avec mon LT 2019. Chaque fois que je démarre le camion la semaine dernière, sans remorque, j'obtiens le message "réparer le système de freinage de la remorque". Je peux ignorer le message et il ne revient pas pendant le cycle de conduite en cours. Si j'éteins le véhicule et que je le redémarre, le message réapparaît. Rien n'a été touché ou modifié d'OE. Je suis curieux de savoir s'il y a eu une réparation commune liée à cette situation. J'ai parlé au comptoir des pièces chez un concessionnaire GM, et il a indiqué qu'ils avaient remplacé beaucoup de contrôleurs ces derniers temps, mais qu'ils ne connaissaient pas la plainte du propriétaire. Étant donné que vous pouvez acheter un nouveau contrôleur OE pour environ 10 $, je suis tenté d'en jeter un et de voir ce qui se passe avant de payer les diagnostics chez le concessionnaire. 

 

[Alain 974]

1 minute ago, Alain 974 said:

 

bonjour, mon Silverado  high country 2020 a le même souci depuis quelques jours... message: "procédez à l'entretien du circuit de frein de remorque" Avez-vous une référence pour votre contrôleur ? Votre souci a-t'il été solutionné avec le remplacement du contrôleur ?