GMC OEM brake controller question

[kittmaster]

Long story short, we've yet to tow our AS anywhere due to delivery issues.

This weekend we plan to start getting used to towing it around.

My question:

The GMC integrated controller (which works when we did a dry test at dealer to setup hitch during walkthrough) has adjustable gain control. Got it.

The multi part question is, when that gain value is "set" to the point of the trailer give a minor "clunk" when the TV brakes are applied, usually most of what I read is that this is the correct "setup" to have. So, after that is set......when driving and you press the brakes of the TV usually it can be a "soft" brake, medium, or hard......etc....or a progressive soft to harder to stop.......type of braking......what does the trailer do? Is it a hard on/off activation using the set gain value of the brake controller or is it a progressive brake increase that tracks the TV brake pressure?

I ask because if I "tap" the brakes to slow slightly, will the trailer try to "drag" me to a screeching halt because it's brake gain is way higher than the small breaking I'm try to do etc.

Clear as mud I'm sure....hopefully someone can decipher/decode and provide some feedback before we "head out".

Thanks,
Chris

[Rich W]

Mine is an after market Tekonsha Prodigy P2, not GMC, but the behavior is probably the same. Brake controllers have a movable something inside that determines how hard you are braking. Sudden braking will apply more energy to the trailer brakes than a slow stop. When I set my controller I do it in a parking lot and then do different stops to see how it will behave.



The guy I bought my AS from said he set his on gravel roads. If the trailer brakes locked up when he stopped he would just dial it back a little. In my experience I have set mine to a number and I just let it stay there. It works well under various conditions but the Prodigy has a manual control lever that allows you to reach down and temporarily apply stronger braking without changing the dialed in number.

[SeaLevel]

There is good information in the Sierra owners manual on how to adjust the trailer brake controller, and how it works. For example:

TRAILER GAIN: This setting can be adjusted from 0.0 to 10.0 with either a trailer connected or disconnected. To adjust the Trailer Gain, press one of the Trailer Gain Adjustment buttons. Press and hold a gain button to continuously adjust the Trailer Gain. To turn the output to the trailer off, adjust the Trailer Gain setting to 0.0 (zero).

TRAILER OUTPUT: This displays anytime a trailer with electric brakes is connected. Output to the trailer brakes is based on the amount of vehicle braking present and relative to the Trailer Gain setting. Output is displayed from 0 to 100% for each gain setting. The Trailer Output will indicate “- - - - - -” on the Trailer Brake Display Page whenever the following occur:

- No trailer is connected.
- A trailer without electric brakes is connected (no DIC message will display).
- A trailer with electric brakes has become disconnected (a CHECK TRAILER WIRING message will also display on the DIC).
- There is a fault present in the wiring to the trailer brakes (a CHECK TRAILER WIRING message will also display on the DIC).
- The ITBC system is not working due to a fault (a SERVICE TRAILER BRAKE SYSTEM message will also display in the DIC).

I normally have mine set at 6 or 6.5.

[ZOZ]

I have a 2018 GMC 1500 Denali towing a 2018 AS FC23FB.


My trailer brake controller is set at 5.


Randy

[Vantair]

I have a 2014 GMC (refresh series) 1500 Denali towing a 2005 25Ft Intl. CCD SS. 5300 dry 6300 wet 740 tongue.

My trailer brake controller is set at 5.5 empty trailer and 6.5+
if loaded up 1/2 water +.

Importantly, we routinely get NO Grade Braking kck-in in tow mode/standard on major many mile 6% declines and must do manual downshifts to get the benefit.

With that steeper grades get some front end pulsing with soft pedal as if antilock is at hand. Nothing we've tried and keep it at 55-60mph from the start on top.We baby this truck and all maint services done.

(Venting)
Local dealer.......no clue or care and simply denies possibility even through we've successfully recreated GB failure 5 out of 6 downhills with shop manager riding along not towing but all in/out tow mode. We are 34K miles total and still under warranty. Frustrating

[Dmmdtm]

If I understand your question, the braking applied to the trailer is consistent with the amount (degree) of braking applied to the vehicle. It's not an "on-off" type of engagement.

[DKB_SATX]

IMHO you want the maximum braking force the brake controller is allowed to deliver to bring the trailer just short of locking its wheels. The brake controller will apply the brakes proportionally to the truck's deceleration, and sophisticated integrated ones may also take into account brake system pressure to get ahead of the deceleration measurement, so unless your gain is set way too high you shouldn't get a lot more braking applied to the trailer than is applied to the truck. I test mine by fully activating the brakes via the controller at low speed and listening for a bit of tire noise. If it's the screech of lockup the gain is too high, if there's not a sharp deceleration and a bit of "scrub" noise from the trailer tires it's too low.

[kittmaster]

Thank you to all, I have a clearer picture of what to expect.

Cheers!

Chris

[ekbruster]

I have a GMC Yukon pulling a 30FC FB Bunk model, but work for GM so get company trucks/SUV's all the time, I find anywhere between 5-6.5 is the ideal range, it really comes down to feel, it will progressively brake with the vehicle so the harder you push your foot too the floor the more break applied to the trailer. I set it so it feels like the trailer is not there, meaning I'm not breaking any harder to stop than if the vehicle didn't have the trailer, and the trailer isn't stopping the vehicle (or locking up the brakes on it). I usually go a bit higher when I have full tanks or doing mountain driving, have been all the way up to 7.5 for those types of conditions but local Michigan driving usually around 6.

[jaybauman]

Originally Posted by ekbruster

I have a GMC Yukon pulling a 30FC FB Bunk model, but work for GM so get company trucks/SUV's all the time, I find anywhere between 5-6.5 is the ideal range...

...I usually go a bit higher when I have full tanks or doing mountain driving, have been all the way up to 7.5 for those types of conditions but local Michigan driving usually around 6.

With my 30FC Bunk and 2015 Duramax, 4.0 is the best setting for me. Is there really that much difference between a Yukon and a GMC Sierra 2500HD for brake gain setting?