Home | Brakes | What Does Service Trailer Brake System Mean

What Does Service Trailer Brake System Mean

March 20, 2024 | Victor Lukasso

As a car owner, one of the warning lights that you might get is the “service trailer brake systemcheck light.

These warning lights notify you of a fault in the car system that needs attention.

In this context, the trailer brake system has been detached, probably due to wiring or other errors.

This article will discuss the meaning of a service trailer brake system alert, its meaning, and possible ways to fix it.


Service Trailer Brake System – Meaning

Trailer Brakes are installed when towing a vehicle to give the driver sufficient control of the towing vehicle.

Trailer Brakes help control the vehicle being towed by regulating its speed, and it’s usually located on the dashboard where the driver can easily access it.

The service trailer brake system warning message indicates that the car has been disengaged from the towing trailer.

Recommended:  Why are my Brake Squeaking After being Replaced?

This could occur when the vehicle being towed doesn’t have enough power, making you unable to control the brakes from the dashboard.

You might also encounter difficulties trying to stop the vehicle, loud noises when you brake, with malfunctioning lights.

Service Trailer Brake System – Causes

Before the service trailer brake system warning light turns on, there should be an issue in the wiring harness of the trailer brake, a blown fuse, a faulty brake light switch, or a lousy trailer brake control switch.

Continue reading as I explain each of these causes;

1. Damaged Trailer Brake Wiring

When the trailer brake wiring harness goes bad, relaying data to other connected components will be difficult.

It’s essential to perform a visual inspection to find the exact wire at fault for getting it fixed and replaced.

Failure to do this will ignite the service trailer brake system warning light.

2. A Blown Fuse

A fuse helps monitor and regulate the amount of power in the system. If a voltage higher than the one a fuse can withhold gets to it, it’ll get blown up.

Recommended:  Which Pedal is the Brake in an Automatic Car

In most cases, this issue could be fixed by replacing the blown fuse with a new one, but if the incident occurs frequently, there might be a more significant issue hiding somewhere.

3. A Faulty Brake Light Switch

The warning light will ignite if the brake light switch fails or becomes faulty.

This can be fixed by replacing the old brake light switch with a new one. They’re located on the brake pedal.

4. Faulty Trailer Brake Control Switch

The trailer brake control switch is often located beneath the dashboard (under the steering wheel for Chevrolet) and is prone to failure because it’s not frequently used.

The first thing to do is to check the connectors and clean dirt, dust, and cobweb that might have gripped them.

This should clear the warning light, but if the reverse is the case, then replace the old brake control switch immediately.

5. Defective Sensor

The brake system makes use of sensors to relay information to all components of the system.

When a component fails to send back signals due to a bad sensor, the warning light will illuminate to notify the driver.

Most times, the light could be associated with several other errors; it’s best to scan them out using an OBD-II scanner.

Recommended:  Brake Caliper Sticking When Hot? Causes and Fixes

You can also seek a professional mechanic’s attention if the warning light’s cause remains unidentified.

How to Reset Service Trailer Brake System

Depending on your car model, the service trailer brake system warning light will likely go out after some time if fixed.

However, to Reset the warning light, you can use an OBD-II scanner to reset the system.

  1. Connect an OBD-II scanner to a port beneath the steering column
  2. Turn the ignition to the “ON” position
  3. Click on the “Read” option on your OBD-II scanner
  4. Select the “Erase/Clear” option on the scanner
  5. You can now disconnect the scanner and turn off your car.

An alternative method to reset the service trailer brake system warning message is to remove the battery’s negative terminal, wait for some time, and reconnect the battery.

That’s it.


Is there a fuse for the trailer brake system?

Installed in the fuse of a trailer brake system is a 30 amp fuse that controls the power supply to it.

As an Amazon Service LLC Program Associate, V. Auto Basics earns from qualifying purchases. See Our Affiliate disclaimer.


Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.