Question about 2021 Chevy Silverado 2500HD Brake Controller

[LJS1211]

Two weeks ago I upgraded trucks and purchased a 2021 Chevy Silverado 2500HD Duramax. Today was the first time towing our trailer. The truck was a beast and definitely pulled a lot better than our previous 2015 Chevy Silverado 2500 gasser and the best miles per gallon I’ve seen for us anyways. The new cameras and trailer apps were also a welcome addition.

The only question/concern I have is with the integrated brake controller. Went through my normal checklist and last thing I did was squeeze the controller to make sure is was working and while yes it engaged the trailer brakes it seemed like it barely did. So I bumped it all the way up to 10 and same results. So I put it back down to 5 and we got on the road.

I’m fairly confident the brakes are working but even turned up to 10 it just didn’t seem like the trailer was grabbing us like the old truck did. Curious what level others have their controller set at and if anyone has experienced anything similar to this. Thanks in advance.

[nomad297]

There have been many discussions here about this. You will find that this is normal and it is almost impossible for you to force the brakes to lock-up on your trailer with the integrated brake controller because it is smarter than you and the aftermarket brake controllers. It’s not going to lock-up the trailer brakes unless the computer decides that they need to be locked-up. It’s not usually something you can force it to do. You will get used to finding the appropriate setting for your brakes and the computer will help you out with that.

Bruce

[Boborc]

You can try turning off the traction control. That seems to override a lot of the automated drive controls. Just a guess if it would affect the Brake control. The owner's manual might have some info on it also.

[jeff64]

On a 2016 TT, is it possible your brakes linings are contaminated or out of adjustment. Have you inspected recently, like when you packed bearings. You should be feeling them come on strong when you move the lever.

[Chuck_S]

I can lock trailer brakes with all of my proportional brake controllers including the Ford brake controller that's part of the towing package so that's not a reason unless the Chevy controller is defective.

Trailer brakes are typically 1930's technology drum brakes with no auto adjustment. They just wear down. New brakes are a prime example as they wear to match the brake drums. Brake adjustment should be in your axle owner's manual or on line. I do it annually when I clean and re-grease the axles. You need this $4 tool. Easy peasy.



-- Chuck

[richp]

I test lock my fiver's brakes with the controller on my 2019 Duramax crew cab every time I start my towing day.

Rich Phillips

[Lumberton1956]

Welcome to the Duramax family. I also have a 2021 2500 Duramax. I pull a Sandpiper 5th wheel weighing in around 13,000 loaded. I keep my brake controller on 6.5 and it seems to do the trick. When I first bought mine I drove it to a high school parking lot and sped up to 20 mph and then engaged electric brakes manually until I could stop adequately without skidding. I could definitely see a difference but I started on the low side and repeated with .5 increases. At 6.5 I was happy and did not try going higher. May try it next time out. Good luck, diesel really makes a difference.

[denville]

#PIT5509: Diagnostic Tip - Integrated Trailer Brake Control System - (Jun 14, 2016)



The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
Some customers may comment that when they have a trailer connected to the vehicle, they get a "Check Trailer Wiring" or "Service Trailer Brake System” message on the DIC. DTC C1114 could be set in the Chassis Control Module (CCM).

Diagnosing these concerns can be difficult because the issue could either be related to the truck or the trailer. This PI is to provide some additional diagnostic information for these three symptoms:

Check Trailer Wiring message
Check Trailer Wiring message with DTC C1114
Service Trailer Brake System message with DTC C1114
Recommendation/Instructions General Information
The trailer brake control system on the new body style trucks is compatible with two types of trailer brake systems: electromagnetic or electro-over hydraulic trailer brakes. The Chassis Control Module K38 (CCM) must determine which type of brakes the trailer is equipped with so the system can output correctly for the trailer's brake system. Because the CCM has to determine the type of trailer brake system that is being used, it can be sensitive to a variety of trailer wiring issues.

The Trailer Brake Power Control Module K133 continuously sends a test pulse out on the trailer control circuit 47, looking for a trailer that has been connected, and also to monitor for circuit faults. The way the test pulse reacts when a trailer is connected is how the CCM determines which type of braking system the trailer is equipped with.



Even after the system detects the trailer, it will continue to send this test pulse on circuit 47, which now is monitoring both the truck and trailer circuitry. Circuit 47 continues to be monitored for any faults so the driver can be notified of any issues that may occur within the truck or trailer, as well as, to determine when the trailer is disconnected from the truck. If the CCM detects an issue, it will either display a "Check Trailer Wiring" or "Service Trailer Brake System" message on the DIC. See DIC message/DIC below.



Electro-over Hydraulic Trailer Brakes
Electro-over hydraulic brake systems have some unique characteristics and here are a couple examples:

The electro-over hydraulic brake pump motor needs a minimum duty cycle of approximately 20-30% to turn on the pump motor. If the user gain is set too low, or during light brake pedal apply the pump motor may not turn on. This is normal. Increasing the user gain or brake pedal pressure will help alleviate this concern.
When applying the brake pedal at 0 mph (stopped) there will be no output from the truck's trailer brake system to the electro-over hydraulic pump motor. This is normal.
Testing The Truck's Trailer Brake System
In many cases, trailer brake issues are the result of trailer wiring concerns and they are not related to the actual vehicle's wiring. Most trailers with these wiring issues do not have high standards in relation to wiring/connections/splices/routing practices (see examples in Step 3 below) when compared to similar automotive practices for wiring/connections/splices/routing. Because of this, the CCM can set faults, which can be hard to determine if they are related to the truck or trailer.



The easiest and fastest way to test the truck is to make a tester using trailer brake magnets. This type of tester utilizes actual trailer brake magnets and will load the truck's electrical system, just like a trailer would do without having to have the complete trailer. Shown below is an examples of such a tester. The trailer brake system will operate with 1 to 4 pairs of trailer brake magnets (1 pair of magnets = 1 axle). It is suggested to make a tester where the pairs of magnets can be added or removed to equal the same number of brakes as the customer's trailer.



Also, it is advised to make the harness long enough so it can be plugged into the truck's 7 way connector and have the magnets placed into the bed of the truck. When the tester is connected to the truck, the DIC will display "Trailer Connected" and GDS2 will show "Electro-magnetic" brakes in the CCM data parameter "Trailer Brake Type", refer to item 1 in "GDS2 Data" section below. If so, the vehicle can be driven to see if any fault messages or DTC's set. If none occur with the tester installed, the truck is operating correctly and the focus should be on the trailer wiring or 7 way connector.



DIC Message/ DTC's

It is important to understand and determine what message is being displayed, as well as, if DTC C1114 is setting. This will help determine what type of fault to inspect for on the trailer. Below is the combinations of message(s)/DTC to determine the type of fault the customer is experiencing:

Check Trailer Wiring message with no DTC. This symptom is caused after the system detects a trailer and an open and/or high resistance occurs in circuit 47/trailer brake output circuit, during the same ignition cycle. NOTE: It is normal for the DIC to display "Check Trailer Wiring" when the trailer is disconnected from the truck while the ignition is in the run position.
Check Trailer Wiring message with DTC C1114 (NO Service Trailer Brake message). This symptom is caused by a short to ground on circuit 47.
Service Trailer Brake System with DTC C1114. This symptom is caused by a short to power on circuit 47 or a poor trailer ground
Trailer Issues
The most likely reason for many of these issues is a poor/loose connection between the truck and trailer 7-way connector. It is recommended to use a "Pollak HD" RV trailer connector, as shown in the latest version of PIT5311. Pollak is the OEM manufacturer of the truck's 7-way connector. By using a Pollak trailer connector, this will provide the best connection possible.
Shown below is an example of a 5th wheel trailer where the trailer harness has been routed over the top of the tailgate and plugged into the truck's bumper connector. While driving down the road, the trailer's wiring harness will bounce up and down (A), causing the trailer's 7-way connector to lose connection (B) with the truck. The fix in this case was to add the 5th wheel/camper wiring harness and route the 7-way connector's harness inside the box of the truck, as shown ©.
Note: This same concern can also happen with bumper pull trailers if there is an excessive length of harness. Securing the excessive trailer harness and installing the Pollak HD RV trailer connector per PIT5311 will help.

Poor trailer wiring connections, as shown below. General Motors does not recommend these type of connections, but many trailers utilize these connections. These type of connections are not robust and are not recommended, especially for brake wiring. Aftermarket trailer sway control devices, like the example shown below. These devices can apply the trailer's brakes to control trailer sway. When this happens, the truck will detect this and set DTC C1114. It will also display a "Service Trailer Brake" message on the DIC. NOTE: If a trailer sways this is likely caused by improper loading of the trailer, refer to the owner’s manual for more information The CCM is detecting the wrong type of trailer brakes. This is normally caused by an aftermarket device wired into the trailer. The example shown below is an electric over hydraulic-to-electric brake adapter. These adapters are used to make a truck that only works with electric trailer brakes work with a trailer that has electric over hydraulic brakes. These adapters are NOT recommended. In addition, the new body style trucks are compatible with both types of trailer brake systems: electro-magnetic or electro-over hydraulic.

[PenJoe]

Originally Posted by Lumberton1956

Welcome to the Duramax family. I also have a 2021 2500 Duramax. I pull a Sandpiper 5th wheel weighing in around 13,000 loaded. I keep my brake controller on 6.5 and it seems to do the trick. When I first bought mine I drove it to a high school parking lot and sped up to 20 mph and then engaged electric brakes manually until I could stop adequately without skidding. I could definitely see a difference but I started on the low side and repeated with .5 increases. At 6.5 I was happy and did not try going higher. May try it next time out. Good luck, diesel really makes a difference.

Great advice. To ad, the integrated brake controller is an extension of your TV brakes. Setting the gain depends on the weight of the trailer, provided the trailer brakes are functioning properly. As an example, I towed a 7K cargo trailer. When it was at capacity, the comfortable gain was 6 to 7. However, when the trailer was empty, the trailer brakes locked up at 1.

The brake controller is designed to work with/without traction control. If you are in varying condition where traction control may become necessary, it should be engaged.

[01tundra]

I test ours every time before we pull out, while letting it roll at idle the trailer brakes will instantly stop the truck on setting 6.5 and will lock the trailer brakes up on gravel. This has been proven to be a good set point with our truck/trailer, of course our trailer only weighs 4,500 lbs.

When we first got the trailer I manually adjusted each trailer brake to right before there was brake pad drag on the drums, that made a big difference.

[nikita]

My DH says ours are at 8 - he's happy with that. We have that same truck as you, but a 2020. But I do have a different question. Yesterday he had to buy DEF, he buys it at an Auto Store or Walmart. Guy at Auto store suggested this new stuff, it's called the Platinum version, it's a lot better for the newer Diesels and the kicker is it's $8 more DH went for the same one he always buys, anyone have any thoughts?

[richp]

Nikita, I have no data to back up my instinct that this is a marketing gimmick.

Rich Phillips

[jrk341]

Originally Posted by nikita

My DH says ours are at 8 - he's happy with that. We have that same truck as you, but a 2020. But I do have a different question. Yesterday he had to buy DEF, he buys it at an Auto Store or Walmart. Guy at Auto store suggested this new stuff, it's called the Platinum version, it's a lot better for the newer Diesels and the kicker is it's $8 more DH went for the same one he always buys, anyone have any thoughts?

If I don't get mine at a truck stop then it's walmart brand.

[{Tpc}]

You might try this test on a gravel road. I've found the same thing happens with my ford, but if your on gravel its easier to pick an adjustment spot. I agree that it seems the "brains" in these newer vehicles are much smarter than we give them credit for! lol

[NMWildcat]

Most of the trucks on the farm are newer Fords and Rams, but we found the integrated brake controllers to be lacking so we installed after market ones and find they work better for us.
My 2007 Duramax of course didn't come with one

[Thomas ho]

does the 7 pin connection in the bed not control trailer brakes?. 2018 chev 2500 ltz .i have one on bumper also " 7 pin".

[PSU Turf]

As stated before, jack up your trailer and manually adjust the brakes. Like most trailers mine is supposed to have self adjusting brakes. They need some additional adjusting every once in a while. I had the same problem-maxed out brake controller and still minimal braking on the trailer. After I manually adjusted the trailer brakes I can lock them up with the controller if desired.

[Wileykid]

Originally Posted by Thomas ho

does the 7 pin connection in the bed not control trailer brakes?. 2018 chev 2500 ltz .i have one on bumper also " 7 pin".

The plug in the bed is the same as the one on the bumper. They are both wired together off a "Y" from the main harness. The one in the bed is used for the cable from a 5th wheel.