Service Trailer Brake System: Meaning, Causes, and Resetting

The trailer brake system is one of the most important parts of modern vehicles. It is used in towing vehicles as an important safety measure. In a vehicle, several warning lights and symbols can be seen on the dashboard that warns about problems with the vehicle. You can easily find the “Service trailer brake system” message on your vehicle’s dashboard.

This warning message informs about an issue with the module or system’s electrical wiring that blocks the power from getting to the trailer. This article explains the service trailer brake system meaning, causes, and how to reset it.

What is a Trailer Brake?

The trailer brake system is used to help the driver in controlling the speed of the trailer and its stopping conditions. This system is an OEM located in the vehicle’s system near the driver’s side of the towing vehicle.

It also has an impact on the braking system, as it takes a little longer to stop when the vehicle has to stop. The settings of this brake controller system can be adjusted from the plus and minus setting on the display.

This system provides additional stopping power to the combination by applying the brakes on the trailer. This assists in reducing the braking distance and ensures that the combination can be brought to a safe stop.

The brake system of the trailer can be fitted in various ways. The system can be handled easily by using camper trailers, boat trailers, horse trailers, and enclosed trailers.

What Does the Service Trailer Brake System Message Mean?

The Service Trailer Brake System message appears on your vehicle dashboard when the trailer brake system has been disconnected due to bad wiring or any other damage. In such conditions, the trailer will not get proper power, and this will also hinder the brake system of the vehicle.

Service Trailer Brake System Message

It’s not like you will only have the warning; you can notice some other symptoms as well. Sometimes, this trailer may not stop due to damage.

You can also notice noise while applying the brakes. Your vehicle’s lights and electrical equipment may not work properly due to unstable power. All of these are the symptoms that result in the service trailer brake system message light.

Causes of the Service Trailer Brake System Message

This service trailer brake system warning message may originate due to a blown fuse, failed brake light switch, or damaged trailer brake control switch. Faulty wiring can also be the reason for this message light on the dashboard of your vehicle.

The following are the major causes of the Service Trailer Brake System message:

  1. Blown Fuse
  2. Bad Trailer Brake Control Switch
  3. Defective Brake Light Switch
  4. Low Brake Fluid
  5. Damaged Wiring
  6. Overheating
  7. Faulty Sensor/Master Brake Cylinder
  8. Damaged Brake Components
  9. Incorrect Brake Adjustment

1) Blown Fuse

A blown fuse is one of the most common causes of the service trailer brake system message illumination. The power of all the electrical components is controlled by the fuse of the vehicle. However, this fuse can blow if excessive voltage is delivered from it.

car Fuse, Causes of the Service Trailer Brake System Message

Sometimes, if you replace the fuse and the problem still exists, a blown fuse can be the result of a big problem. Use the manufacturer’s manual to properly locate the fuse and check if the fuse is blown or not. If the fuse is blown, replace it with a new one.

2) Bad Trailer Brake Control Switch

In modern cars, the trailer brake controller system is usually located under the dashboard. Sometimes, the trailer brake control switch gets damaged and needs replacement. There may also be the possibility that dirty connectors are causing this bad trailer brake control switch.

Trailer Brake Control Switch

In the Chevrolet, the service trailer brake message lights up due to the defective trailer brake control switch located underneath the steering wheel. In such cases, clean the connectors and check whether the issue has been resolved or not. If not, replace the switch.

3) Defective Brake Light Switch

A faulty brake light switch is one of the famous reasons of the service trailer brake system message illumination. This brake light switch is inexpensive and easy to replace.

Brake Light Switch, causes of Service Trailer Brake System

The brake light switch is present near the brake pedal, and it is easily replaceable. But after replacing the switch, ensure that the switch is properly fixed.

4) Low Brake Fluid

Brake Fluid

The hydraulic system of the trailer contains the brake fluid. This brake fluid may become low due to wear and tear. This low fluid level will result in a glowing warning message.

5) Damaged Wiring

Faulty wiring can be the cause of the service trailer brake system warning message. With the damaged wires, the electrical system cannot be forwarded to its destination. Similarly, these damaged wires can be the reason for the glowing service trailer brake system.

Damaged Wiring

If you are facing this issue and do not have proper knowledge about the electrical system, you can ask for professional help. Don’t forget to check the wires before fixing them.

6) Overheating

car Overheating

With the huge weight, the braking system may get overheated, and this overheating will cause the warning message to appear. In this case, if the message is not entertained at the required time, this may lead to brake failure.

Read More: Engine Overheating Symptoms and Causes

7) Faulty Sensor/Master Brake Cylinder

A master cylinder and some sensors are used by the brake system to check the performance of the components in the system. If any of these components fails or is damaged, the system will show a warning light.

Master Brake Cylinder

Sometimes, this service trailer brake system message appears with some other warning signs that point to a bigger problem in the vehicle’s internal system. Remember, with the increase in the number of defective sensors, the repair cost will also increase.

8) Damaged Brake Components

Brake Components

Rotors, brake pads, and drums are the components of the brake system. If any of these components get damaged or wear out over time, the service trailer brake system light may appear. This may decrease the performance of the brake system, and this bad performance then triggers the warning light.

9) Incorrect Brake Adjustment

The brake adjustment is required to enhance the overall performance of the trailer. The improper adjustment of the brakes will cause the warning light to appear.

Read More: Brake System Light Meaning and Symptoms

How to Reset the Service Trailer Brake System Message?

The reset method of the service trailer brake system warning message depends on your car’s model. Following are the basic steps that should be followed to reset the service trailer brake system message:

  1. Set the engine off and let it cool down properly.
  2. Now, disconnect the trailer from your car.
  3. Just wait for 2 to 3 minutes and reconnect the trailer.
  4. Now, turn the ignition key in the on position but do not start the engine.
  5. Search for the trailer brake control module. This module is usually labeled as “Trailer Brake Control Module” and is located on the driver’s side.
  6. Keep holding your vehicle’s override button for about 4 to 10 seconds.
  7. Release the button and check if the service trailer brake message system goes off.
  8. If the light is still on, repeat the above steps about 4 to 5 times.

Cost to Fix the Trailer Brake System

The repair cost of the service trailer brake system varies according to the vehicle model and labor cost. The average cost to fix the service trailer brake system is approximately $310, including labor and the installation job.

The replacement of the trailer brake system also depends on the condition of the trailer brake and the job done by the mechanic.

Differences between Surge Brakes and Electric Trailer Brakes

FeatureElectric Trailer brakesSurge Trailer Brakes
Brake System TypeElectricalHydraulic
EffectivenessHighly effective in abrupt stops or downhill descents.minimally effective in abrupt stops or downhill descents.
MaintenanceA periodic inspection and adjustment of the brake shoes are needed.Periodic inspection of fluid levels is needed.
CompatibilityNeeds compatibility with the towing vehicle’s electrical system.compatible with most of the trailers
Method to activate Electrical signalsInertia or surge
ControlControl box fitted in the tow vehicle.No control box is present.
Dependence on the towing vehicleDependents on the weight and speed of the towing vehicle.Dependents on the weight and speed of the towing vehicle.
Frequently Asked Questions

Is it safe to drive with a "Service Trailer Brake System" message?

No, it’s not safe to drive with the service trailer system message. It is not recommended that you ignore this message if you are towing a trailer. This will cause problems if you apply brakes to the trailers. If the problem is not fixed and you just keep driving the vehicle with the light on, then it may cause some serious issues.

How often should you service the trailer brake system?

The trailer brake system of your car should be serviced after 12,000 miles or once a year. If the trailer is used frequently or for a long time, it may require servicing the brakes more often. Observe some other symptoms of the damaged brakes; you can also keep an eye on how frequently you use the trailer. Always maintain the braking system of the vehicle and ensure that the brakes are in good condition.

How do you reprogram a trailer brake control module?

A specific diagnostic tool is required to reprogram the trailer brake control system. For several brake control systems, the controller can be used to adjust the brakes manually.

How do you troubleshoot an electric trailer brake controller?

A proper, compatible diagnostic computer is required to check an electric trailer brake controller. In many cases, technicians may only need a multimeter and the wiring diagram for this purpose.

How do you service a brake system?

  • Frequently check the brake fluid level to maintain the proper level in the hydraulic system.
  • Check the brake lines.
  • Replace the brake fluid.
  • Look for the brake pads on the vehicle and replace them if necessary.

Can a bad activate the trailer brake light?

To resolve the issue with the turn signals, check and replace the appropriate trailer RT or LT fuse as necessary. This action will also address any problems with the brake lights since they share the same fuse.

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