2018 Sierra 1500 with ITBC / Airstream with Disc Brakes

[nvestysly]

Situation: We recently purchased a 2018 1500 Sierra with the factory Integrated Trailer Brake Controller (ITBC). Our 1992 Airstream was upgraded to electric/hydraulic disc brakes several years ago and we've been using a Prodigy P2 brake controller in our existing tow vehicle. I was disappointed when setting up the parameters in the Driver Information Center on the Sierra that I didn't see any choices for "brake type" when initializing the ITBC. I suspected the chances of the factory ITBC working with our electric/hydraulic brakes were less than 50-50.

Upon initial hook-up to the 2018 Sierra, the factory ITBC worked once then I received a message on the Driver Information Center indicating Service Trailer Brakes. I had no brakes. If I disconnected and reconnected the trailer 7-way connector while I turned the vehicle on and off the vehicle would reset but situation would repeat - the trailer brakes would work for a moment then the error message would appear again.

First Try: I called the GMC dealer and they assured me the ITBC would work with electric/hydraulic brakes. They suggested a few troubleshooting techniques which included double-checking the ground path of the 7-way connector to the trailer chassis as well as cleaning the contacts, checking for good connections, etc. I was optimistic but soon found this did not solve the problem. I do however have a cleaner connector on the trailer now. The factory ITBC continued to demonstrate the same operation - no brakes.

Alternate Sources of Information: I was somewhat prepared for this problem. We didn't buy the 2018 Sierra because of its ITBC and as I mentioned the chances of it working for us were low. I've found several threads on a variety of truck forums that indicate it's hit-or-miss whether the ITBC will work with electric/hydraulic trailer brakes. Some people say put an electric brake magnet in the system so the vehicle senses electric brakes and it will then work with electric/hydraulic. That sounds promising but I decided not to go down that road. At best the factory ITBC has "gain" but doesn't have the "boost" feature offered by the Prodigy P2 and other aftermarket brake controllers. GM indicates "boost" is added via their on-board electronics but once again... I had experience with the Prodigy product and it has worked on our trailer for over 100,000 miles.


More Information: I contacted Tekonsha, the manufacturer for Prodigy products, and asked to speak to a technician (not customer service). The person I spoke to was very informative and recommended the P2 (or P3) product for use with electric/hydraulic trailer brake systems. When I reiterated that the truck has the factory ITBC they walked me through the steps of using their 3016-P wire harness with a modification so it would bypass the ITBC installed in the truck. The wiring is straightforward but it took me most of the day to perform the install.



Wiring Steps: Install the brake controller in a suitable location. Use wiring harness 3016-P to mate with the brake controller interface connector provided by GM under the dash, left of steering column, in the electrical box. Before connecting to the GM interface connector, cut the blue wire in the 3016-P harness and run a 12 gage blue wire from that point under the dash all the way back to the blue wire at the 7-way connector on the truck. Cap the open ends of the cut wires for safety. The blue wire must be routed all the way back to the within a few inches of the 7-way connector to bypass any GM electronics. Use wire loom and suitable zip-ties and sleeving to protect the wire that been routed.

Related Information: After some insistence on my part the GMC dealer did provide a Technical Service Bulletin on the subject. GM doesn't indicate the ITBC may not work in all cases but refers instead to "customer requests" to install an aftermarket trailer brake controller. The TSB I located for our vehicle is #PIT5282D (also known as 4997449). These numbers may vary for other vehicles.

I wasn't originally going to post this information thinking there probably aren't many forum members with electric/hydraulic brakes. However, I found the thread below (after the fact) and realized our issue may be helpful to other forum members. Thanks to forum member evsjr for prompting me to provide the information in an organized manner.

http://www.airforums.com/forums/f439...kes-52672.html

[GMFL]

Great write up. This is why the forum is so great. Guys like you taking the time to post quality information that took you a lot of time to acquire so that the rest of us can benefit.
Bravo!

[nvestysly]

OOPS, I forgot to attach a copy of the Prodigy installation document that comes with the 3016-P wire harness. The attached document describes installing the aftermarket trailer brake controller to the connector under the dash but does not describe bypassing the factory GM electronics by cutting the blue wire and running a 12 gage wire back to the 7-way connector.

I also found a PDF copy of the GM document describing the aftermarket trailer brake controller installation. The GM workaround accomplishes the same thing that the Tekonsha technician described but performs the wiring modification under the hood rather than under the dash.

I like the Tekonsha modification for its simplicity - cut the blue wire on the Tekonsha wire harness (under the dash) and cut the blue wire at the 7-way connector. Note the GM instructions refer to a GM part number for a brake controller pigtail harness. The Tekonsha (and other brands) make a two-ended wire harnesses to connect the aftermarket brake controller to the under dash connector. Many modern vehicles have a connector under the dash to connect a brake controller as shown in the pictures.

TSB_installing_aftermarket_TBC_with_ITBC.pdf

Prodigy_wire_harness.pdf

[white laker]

I had the exact error message and subsequent total loss
of brakes on my 2015 Sierra 1500 max tow and my 2008 34 classic slider. I contacted my dealer, (Canam) and they installed a magnet in the brake circuit. Problem solved and never had a concern again. The G.M. controller works really well with the Dexter brakes. Happy camper here!
Pete

[switz]

When I converted our 2014 Classic to Disc brakes, the 2012 Ram 2500HD factory brake controller was a best very erratic. We installed the DirecLink brake controller as below:

DirectLink Brake Controller
Chris Romanoff
847-816-8800 ext 204
bypass Ram brake controller


Ran #10 thru 30 amp breaker on positive along side #10 from negative to rear of truck 7 wire plug

Ran #10 thru 30 amp breaker on positive to DirecLink under dash

Ran #10 blue from DirecLink under dash to rear of truck 7 wire plug

Disconnected these three original factory wire harness wires from truck wire harness at plug which isolated the truck brake controller and no error codes are thrown.

[thewarden]

We had the exact same issue with our 2016 GMC when it was new. Took it into the dealer and they wound up removing some part of the trailer wiring harness, reset the error message and we have not had an issue since. I do not know exactly what they did, but the point is the dealer has a fix that allows you to use the integrated controller, which has worked very well since the fix.

[gypsydad]

No issues with my Ford.

[trumpetguy]

You can find my posts in the Classic forum but I had the same problem with my Ram 2500 ITBC. The solution after some trial an error was the Prodigy P2. The plug went right into my factory harness and it works great. If anyone has an older unit with disc brakes be sure to check for the Dexter actuator pump and hydraulic line recall.

[Steve Bryant]

I've owned three Tekonsha aftermarket brake controllers on previous tow vehicles but none of them demonstrated the finesse of the integrated trailer brake controller (ITBC) on my 2017 Sierra 6.2L with Max Trailering Pkg. (NHT). Most of my career was spent in aviation electronics for a general aviation OEM manufacturer, Beech Aircraft. I understand the workings of the current aftermarket controllers (inertia based) versus the integrated systems offered by vehicle manufacturers (brake master cylinder pressure and speed). Also, the integrated systems have built in diagnostic functionality for self-test/proper operation. This diagnostic function can trip-up the integral system on any ITBC. The integral controller is looking for the resistance of a brake magnet (actually, up to six of them for a three axle trailer) for feedback to properly send out the proper amount of braking current. Electric over hydraulic systems can have a very high input resistance or impedance and the truck sees it as if the trailer brakes are disconnected or malfunctioning. CanAm installed a trailer brake magnet in parallel with the input to white laker's trailer brake controller input to make the truck acknowledge that it is hooked up to a trailer brake circuit and everything is working properly.

I was hesitant to write this post, because I don't want to seem mean-spirited about the solution that Tekonsha recommended and the original poster (nvestysly) used. However, I've gone ahead and stuck my neck out a little in the hope that others reading this thread will realize that OEM integrated brake controllers should work fine with electric over hydraulic trailer brakes. But it may take a little modification, like the magnet idea. Some electric over hydraulic systems may be designed with a lower input impedance (maybe two to five ohms) to "trick" the vehicle's controller into "seeing" the electrical load from traditional electric trailer brakes. In general, an integrated controller is the best in my opinion.

[AlinCal]

I have a 2018 silverado with the integrated controller and really like it over the tekonsha that was in my tundra. Trailer has stock drum brakes though.

[Steve Bryant]

I did a little more research and found with the posts on this page of a thread in another forum. It summarizes the solution pretty well if required.