braking problem

[LarryDel]

We have a 2022 Forest River Flagstaff Microlite 21FBRS travel trailer. My tow vehicle is a 2012 Chevrolet Silverado 6.2L with the max trailer package. On a recent trip, our truck brakes had a problem. Had to push all the way to the floor to stop and it took a while. And we were on a flat road. Fortunately we were close to home, so we drove slowly and carefully to our house. We disconnected the trailer. I then drove my truck for a while. The brakes worked just fine. So I concluded the problem was with the trailer. My question is why did the trailer cause my truck brakes to fail?

[ktmrfs]

when was the last time the brake fluid was flushed and replace? Brake fluid is highly hydroscopic, it doesn't take much moisture in the fluid to have brake fade due to boiling fluid.

[Grit_dog]

^The truck is a half ton with vacuum boost.
GM never put the 6.2 into a HD and hasn’t had hydro boost brakes since the 6.5 diesel era

[JBarca]

LarryDel wrote:
We have a 2022 Forest River Flagstaff Microlite 21FBRS travel trailer. My tow vehicle is a 2012 Chevrolet Silverado 6.2L with the max trailer package.

Hi Larry,

H'mm, I read through all the responses so far, including yours, lets get some more info on your camper and the truck to maybe help better.

1. Is this your camper, https://forestriverinc.com/rvs/travel-trailers/flagstaff-micro-lite/21FBRS/6235

2. It appears the way FR rated this, your GVWR is 5,837# (UVW + CCC) Did I get the GVWR correct? (the truck is OK with that size trailer, just want to make sure we know the camper in question)

3. Have you weighed the camper loaded? If not we can assume you are full GVWR.

3A. What is your added truck bed weight of camping stuff?

4. Is your 6.2 liter Chevy truck a 1/2 ton or 3/4 ton? I'm after this for the braking size. GM often uses the 6.0 gasser in the 2500 back in 2012 time frame, but maybe not always on some high end trim models, just want to confirm.

5. Rather then digging for it, does your truck have a hydra boost braking or vacuum boost braking master cylinder setup?

6. Does your truck have and you are using, the GM integrated trailer brake controller? It appears to be an option per the truck manual. Or are you using an aftermarket controller, and if so, what brand/model?

7. You stated you were using a gain of 2.0 with this new trailer, did you do the brake controller setup test to find the gain required with the manual lever to just be under trailer wheel lockup at approx. 20 - 25 mph? Or was your gain setting of 2.0 from a prior camper and you just left it there? I'm after this to see how the brake controller and the new camper brakes are set.

8. Approx. how many miles have been towed on your new camper since you bought it?

9. Have you towed the camper since this event occurred and did everything work OK or not?

Sorry for all the questions, I'm trying to find a possible link between your setup and the effect of the brake pedal you experienced.

Hope this helps,

John

[Grit_dog]

LarryDel wrote:
I did not try the applying the brakes manually with the brake controller. No need to as we were only going 45 miles per hour on a flat surface and the truck breaks were enough to bring us to a safe stop, although I had to put my foot all the way to the floor. I did not try increasing the gain as it was set at 2.0 which is more than enough to work. Again, what caused my truck brakes to fail? My truck brakes work fine as soon as I disconnect the trailer. Never had this problem before in 10 years of towing.

This is one of the most contradictory statements I've read in a while.
Although it appears that whatever happened on that flat road in Delaware could forever remain a mystery.
I cannot begin to even surmise, after 30 + years of driving more, towing more and working on more vehicles than most people, how that particular sequence of events would happen and then correct itself immediately.
Although you may be saying that the truck brakes still "don't work" when the trailer is plugged in....

[valhalla360]

LarryDel wrote:
I did not try increasing the gain as it was set at 2.0 which is more than enough to work. Again, what caused my truck brakes to fail? My truck brakes work fine as soon as I disconnect the trailer. Never had this problem before in 10 years of towing.

2.0...out of 10.0? It may be that they work but barely. How strong is the pull if you just activate the trailer brakes manually?

Add in a loose or corroded connection and you could see a sudden reduction in braking from the trailer brakes. Now the truck brakes are asked to cover both truck & trailer and truck brakes may overheat.

Of course, this is just a guess as it's not clear from your description and there is no direct interaction between the trailer brake controller and the truck brakes.

[opnspaces]

Definitely getting the truck brakes checked out was a good start. Now that you know they are good it's time to focus on the trailer.

Maybe the truck brakes never failed. The problem is the trailer brakes failed and the weight of the trailer was too much for the truck to stop alone.

Could you have driven over something in the road that broke the brake wire under the trailer? I would carefully inspect the umbilical cord for any damage. Then crawl under the trailer and follow the brake wires seeing if anything is cut or broken.

Yes the problem could very well be in your 7 pin. Have you recently had issues where the trailer lights sometimes don't work until you unplug and replug the connection multiple times?

Maybe hook the trailer back up and pull it at about 10 mph and slide the manual lever over full. Do the trailer brakes seem to engage?

[LarryDel]

I did not try the applying the brakes manually with the brake controller. No need to as we were only going 45 miles per hour on a flat surface and the truck breaks were enough to bring us to a safe stop, although I had to put my foot all the way to the floor. I did not try increasing the gain as it was set at 2.0 which is more than enough to work. Again, what caused my truck brakes to fail? My truck brakes work fine as soon as I disconnect the trailer. Never had this problem before in 10 years of towing.

[Krusty]

Did you try applying the trailer brakes manually with the brake controller? What happened? Did you try increasing the gain?

[LarryDel]

I had my truck brakes checked. They are fine. Also brake fluid is full, no leaks. I have been towing travel trailers for more than 10 years. Up and down mountains 10,000 ft, 8% grade. Never had a problem. Worked just fine previous 4 days in the mountains of Western Maryland. This happened on a flat surface while driving through Delaware which is flat as a pancake. Could the 7 pin connection be the problem? Mystery continues.

[JRscooby]

Lwiddis wrote:
And low fluid means a leak most of the time.

Not always. As the pads wear more of the fluid stays in the cylinder of calipers. This can show as low fluid.

KD4UPL wrote:
I don't of any possible way trailer brakes can disable truck brakes.

Non-functioning trailer brakes cause a severe overload of TV brakes. Overheated brakes have less stopping power.
I have heard hot fluid can make pedal feel strange.

[KD4UPL]

I don't of any possible way trailer brakes can disable truck brakes.

[klutchdust]

Tyler0215 wrote:
Get the truck brakes checked NOW! The next time they fail you might be coming up to a red light at a busy intersection.
Asking for brake repair on a discussion forum won't stop the truck.

That's what emergency brakes are for.
In a panic stop (Wrong way driver coming at me on 14 in Mojave ) I pushed the pedal to the floor, trailer brakes locked and the rig kept moving. The anti lock brakes are part of the equation also. Truck brakes are not going to lock and it gives you the impression that the truck is not stopping but it is. It traveled the same distance, my guess, as if the wheels were locked and you were skidding. My brake pedal was hitting the floor. My brakes didn't fail. The trailer brakes did their job.
Not sure what the OP experienced. Not enough information.

[klutchdust]

Grit dog wrote:
There's more to what you just posted.
Truck brakes don't "not work" and then work again.
How much experience do you have towing and how well do the trailer brakes work?

Neighbors truck had similar symptoms, not towing though. Had to push the pedal real hard sometimes. The master cylinder was going bad. replaced that and the booster and all is good.

[Lwiddis]

And low fluid means a leak most of the time.