What does U1040 mean on a Chevy?

U1040. Loss of Class 2 Communications With ABS. Applies to Silverado, Sierra, Tahoe, Suburban, Yukon.

What causes U1040 on a Chevy?

Failed electronic brake control module (EBCM) Open Class 2 serial data line to the EBCM Blown EBCM battery or ignition fuse Corroded EBCM data connector pins Another failed module shorting the Class 2 bus

How do I fix U1040 on a Chevy?

Check EBCM fuses, powers, and grounds first Measure Class 2 data line voltage at the EBCM connector Isolate modules one at a time to find a bus-shorting module Inspect the data harness for chafing along the frame Replace the EBCM only after the data line proves intact

Code

U1040

Loss of Class 2 Communications With ABS

Category: Network Communications
Severity: Check Engine Light
Applies to: Silverado, Sierra, Tahoe, Suburban, Yukon
Related: No single generic twin. See OBD Codes List

What it means

U1040. Loss of Class 2 Communications With ABS. This Chevy-enhanced code applies to Silverado, Sierra, Tahoe, Suburban, Yukon.

Findings, check these first

Failed electronic brake control module (EBCM)
Open Class 2 serial data line to the EBCM
Blown EBCM battery or ignition fuse
Corroded EBCM data connector pins
Another failed module shorting the Class 2 bus

Standard procedure

Check EBCM fuses, powers, and grounds first
Measure Class 2 data line voltage at the EBCM connector
Isolate modules one at a time to find a bus-shorting module
Inspect the data harness for chafing along the frame
Replace the EBCM only after the data line proves intact

Look up another code

Press / to jump to the box. Chevy-enhanced powertrain, body, chassis and network codes.

Sources and review

Review: no source links are recorded for this entry.

Last updated 2026-09-13.

Report a correction for U1040. Include your vehicle, the issue and a source if you have one.

This fault is part of the GM ABS and StabiliTrak family. The GM ABS and StabiliTrak codes guide covers the check order.