Traction and cruise control issue

RACEFAN54-49090

MEMBER
2018 GMC SIERRA
6.2L
V8
4WD
AUTOMATIC
34,000 MILES

When I pull my 7x12 double axle trailer everything goes great until the outside temperature gets above 75 or 80. At that point my cruise control and traction control become disabled and I get a low brake fluid message. When checked the brake fluid is fine and everything works properly except cruise and traction control. When taken to the dealership they read the codes but find nothing wrong. After the temperature goes below 70 everything enables again. What gives?

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Couple questions to try and narrow this down. First, does this happen at all if you are not towing the trailer?

If not, how much are you towing on this trailer? What is the weight of the trailer and load combined? Is there a certain point in weight that this starts? Basically we need to try and identify what systems are involved depending on if this is weight related.

Also, when you took it to the dealer did you bring your trailer as well to show them what it is doing? If not, I would suggest doing that as well.

Also, we should be checking for codes when this is acting up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let's start with this and go from there. Thanks

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Wednesday, April 7th, 2021 AT 6:25 PM

RACEFAN54-49090

MEMBER
2 POSTS

It does not happen when not pulling the trailer. Also it happens when the trailer is loaded or empty. Thanks

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Thursday, April 8th, 2021 AT 4:03 AM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. So I doubt it is weight related but it could be so that may have to be brought back in. However, we can rule that out or prove it is weight related by towing the trailer but do not plug the trailer connector in.

Does this vehicle have integrated trailer brakes or have you added a trailer brake controller?

If this doesn't happen with the trailer unplugged then we have a corruption of the CAN bus network. This is why we need to know if you have added a trailer brake controller. If so, it may have failed and is causing communication issues which is why it is not setting codes when you take it in.

Let us know this info and we can go from there. Thanks

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