Brake Fluid Level Sensor Issue for Chevy

Owners of 2014-2017 Chevy Silverado, Suburban or Tahoe vehicles may comment about a “Service Trailer Brake” message in the driver information center.

When checking for DTCs, U0415 (Invalid Data Received from Electronic Brake Control Module) may be set in the chassis control module. It may also be noted that this message occurs during hard braking, acceleration and/or turns. This concern could be caused by the brake fluid level being near the minimum level.

The brake fluid level sensor may momentarily signal that the brake fluid level is low, as the fluid sloshes in the master cylinder reservoir during hard braking/acceleration/turns. The brake fluid level sensor is a direct input to the EBCM. The ECBM sends the brake fluid level data to the chassis control module via the high-speed LAN communication buss. When the chassis control module received the message that the brake fluid level was 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.”  Fill the master cylinder brake fluid level reservoir to the maximum level. Brake fluid could be low due to normal brake pad wear, leaks, etc. If pad wear or leaks do not appear to be the issue, inspect the rear of the master cylinder to determine if it may be leaking into the brake booster.