This bulletin applies to 2014 Chevy Silverado 1500, 2015-2018 Silverado, 2019 Silverado LD, 2015-2020 Suburban and 2015-2020 Tahoe vehicles equipped with a trailer brake system.
The Service Trailer Brake message may appear in the DIC. When checking for DTCs, a U0415 (Invalid Data Received from Electronic Brake Control Module” may be set in the chassis control module.
It may also be noticed that this message occurs during hard braking, acceleration and/or turns.
The concern could be caused by the brake fluid level being near the minimum level in the master cylinder reservoir. The brake fluid level sensor may momentarily signal that the brake fluid is low as it sloshes in the reservoir. The brake fluid level sensor is a direct input to the EBCM. The EBCM sends the brake fluid level data to the chassis control module via the high speed LAN communication bus.
When the chassis control module receives the message that the brake fluid is low, it sets DTC U0415 and commands the “Service Trailer Brake” message on.
The brake fluid level sensor data can be monitored using the scan tool GDS2 under the EBCM antilock braking data list parameter “Brake Fluid Level Sensor”. It will display either “OK” or “Low." Make sure that the brake master cylinder reservoir is full (fluid at the full mark).
