NHTSA ID Number: 10081241
Manufacturer Communication Number: PIT5509
THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN ON HOW TO DIAGNOSE AND REPAIR VEHICLE THAT MAY HAVE A “CHECK TRAILER WIRING” OR “SERVICE TRAILER BRAKE SYSTEM” MESSAGE ON THE DRIVER INFORMATION CENTER WHEN A TRAILER IS CONNECTED TO THE VEHICLE. DIAGNOSTIC TROUBLE CODE C1114 SET IN THE CHASSIS CONTROL MODULE. CHASSIS CONTROL MODULE HAS TO DETERMINE THE TYPE OF TRAILER BRAKE SYSTEM THAT IS BEING USED. THE CHASSIS CONTROL MODULE CAN BE SENSITIVE TO A VARIETY OF TRAILER WIRING ISSUES. THE TECHNICIAN WILL NEED TO MAKE A TRAILER TESTER USING ELECTRIC TRAILER BRAKE MAGNETS AND 7-WAY TRAILER CONNECTOR TO DETERMINE IF IT IS A VEHICLE OR TRAILER ISSUE. IF THE CONCERN IS NOT DUPLICATED WITH THE TESTER INSTALLED, THE VEHICLE IS OPERATING CORRECTLY AND THE FOCUS SHOULD BE ON THE TRAILER WIRING OR 7 WAY CONNECTOR.
13 Affected Products
|Subject:||Diagnostic Tip – Integrated Trailer Brake Control System|
|Models:||2014 Chevrolet Silverado 1500|
|2015-2016 Chevrolet Silverado, Suburban, Tahoe|
|2014 GMC Sierra 1500|
|2015-2016 GMC Sierra and Yukon Models|
|With Integrated Trailer Brake Control (ITBC) system RPO JL1|
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
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
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 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.
Making the Tester
- 7 way RV trailer connector (example: Pollak Heavy Duty 7-Way Part # 12-706 ) Qty: 1
- Electric Trailer Brake Magnets (example: Dexter Axle Part # K71-104-00 ) Qty: 2, 4, 6, or 8
- 12 gauge wire and terminals/connectors Qty: as needed
Connect two 12 gauge wires to the 7-way RV trailer connector: one to the “Ground” terminal and a second to the “Brake Controller Output” terminal (circuit 47), shown below. Connect the other ends of the 12 gauge wires to the trailer brake magnets. All magnets must be connected in parallel so each magnet wire is connected to the Ground and Brake Controller Output wires from the 7 way connector.
Note: Do NOT connect the magnets in series with each other.
If, after using the tester shown above, the truck functions properly, you may follow the diagnostic tips listed below to help diagnose a trailer related issue. Trailer issues are NOT covered under warranty, but this information listed below can be used to help the customer/trailer supplier understand and correct any trailer related issues if they so choose.
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.
GDS2 (scan tool) can be used to view several different data parameters in the CCM for the trailer brake system. The Trailer Brake Type and Trailer Brake Control Output Circuit parameters listed below can be helpful to make sure the CCM is detecting the correct trailer brake system in addition to which type of fault it has detected.
To view “Trailer Brake Type” build GDS2 as follows: CCM->Data Display -> parameter “Trailer Brake Type”: “Electro-magnetic”, “Electro-over hydraulic brakes”, or “Undefined” (this is displayed with no trailer connected). Example, shown below is a trailer equipped with electromagnetic trailer brakes.
To view “Trailer Brake Control Output Circuit” 47 faults, build GDS2 as follows: CCM->Data Display -> parameter “Trailer Brake Control Output Circuit”: Okay, Short to Ground, Short to Power, or Unknown. Example, shown below is a trailer with a short to ground on the trailer brake circuit.
- Trailer Brake Type Parameter
When the trailer is connected, this parameter should be used to make sure the CCM has detected the correct type of trailer brakes. If the CCM is detecting the wrong type of trailer brakes here are a couple examples that could cause this:
- Trailer Brake Control Output Circuit Parameter
When the trailer is connected, this parameter can be used to help determine what type of fault the system has detected on circuit 47, which could lie within the truck or trailer.
Sample Wiring Diagram
Note: As always, use SI to look up the latest wiring diagrams for the vehicle being worked on.
- 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 (C).
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.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
Bulletin No.: PIT5509
- UNIVERSAL SYSTEM: Universal electronic brake control system designed to make trailer towing safer and easier
- FITS 1 TO 4 AXLES: Fits 1 to 4 axle trailers to deliver a signal from your vehicle's brakes to your trailer
- BATTERY PROTECTION: Features reverse battery protection for both vehicle and breakaway
- MOUNTING VERSATILITY: Numerous mounting options offer versatile installation
- INCLUDES 1 BRAKE SYSTEM: Includes 1 electronic brake control system for 1 to 4 axle trailers
- A distinct, easy-to-read LCD display with multiple screen color options, displays in English, French or Spanish
- Diagnostics show output current, battery, brake, and output voltage and warning system alerts to No Trailer Brake situations
- Boost feature allows for different levels of customized braking, select Electric over Hydraulic or Electric trailer brake mode
- Integrated Plug-N-Play port for 2-plug adapters and Snap-in mounting clip allows user to remove and store the control when not in use
- Compact, dash-hugging design. Electric trailer brake control for up to 4 braking axles.
- INSTALLS QUICKLY: This 100% solid-state electronic with a small compact design mounts in any direction, no leveling required. Pre-wired plug-and-play feature allows for quick and easy connection to 2-, 4-, 6- and 8- brake systems.
- ADJUSTS EASILY: Two separate easy push-button adjustment controls (output and sync) allow for not only different trailer weights (output) but also the speed of activation (sync) depending on your driving style.
- DIGITAL DISPLAY: Bright and prominent digital display clearly indicates the output setting, sync setting, brake overload or short connection.
- SAFE & SECURE: This device includes advanced internal circuit protection to help prevent damage and is for use on 12-volt negative ground systems only. Includes a limited lifetime warranty.
- PORTABLE. The Echo trailer brake controller has a non-invasive install and is easily transferrable from one vehicle to another. It plugs into any 7-way connector, wirelessly links to your smartphone using Bluetooth
- SMARTPHONE-READY. The Echo brake controller wirelessly syncs with Apple or Android smartphone, turning it into a brake controller interface with the Smart Control app (Warning: Avoid distracted driving. Only make adjustments when vehicle is stationary)
- ZERO-TOOL INSTALL. Installing this aftermarket trailer brake controller is as easy as plugging in a 7-way trailer wiring connector. It requires no tools, no extra wires and no hardware
- HIGHLY RESPONSIVE. Echo uses a triple-axis accelerometer to provide smooth, safe braking. It maintains responsive braking, even when your phone screen is locked, receives incoming calls or if the Bluetooth connection is lost
- VERSATILE. This electronic trailer brake controller easily transfers between vehicles and trailers and works on virtually any trailer with 1 to 2 axles (2 to 4 brakes). It is also fully compatible with cruise control, anti-lock brakes, low-voltage systems
- Comes with Direct fit wiring harness, brackets, Hardware
Last update on 2021-01-19 / Affiliate links / Images from Amazon Product Advertising API
Last update on 2021-01-19 / Affiliate links / Images from Amazon Product Advertising API