2015 Chevy Colorado: Diagnosing No Communication with ABS Module

Initial Diagnosis and DTC Scan

• 💡 The vehicle, a 2015 Chevy Colorado, presented with ABS, brake, and traction control lights illuminated, and non-functional cruise control.
• 🎯 The customer was referred from another shop due to their equipment not being sensitive enough for this particular issue.
• 🔍 Upon connecting a diagnostic tool, 13 codes were found, with the EBCM (Electronic Brake Control Module) showing as 'gray,' indicating a loss of communication.
• ⚠️ Multiple "lost com with brake module" codes were present, along with a "lost com with HVAC module," suggesting a central communication problem.

Power and Ground Checks at the EBCM

• 🛠️ The initial diagnostic plan involved checking powers, grounds, and serial data communication to the EBCM.
• 📌 The wiring diagram revealed the EBCM requires battery positive voltage at all times, a ground, and serial data lines.
• ⚡ A physical inspection of the EBCM connector showed two battery positive feeds (60 amp and 30 amp) and a ground.
• ❌ Testing revealed a lack of power on the red with yellow wire, indicating an open circuit.

Troubleshooting the Open Circuit

• 💡 A temporary jumper wire was used to supply power to the EBCM, which allowed communication with the scan tool, confirming the open circuit.
• 🔍 The ABS valve fuse (F22, 30 amp, red with yellow wire) was inspected and found to be undamaged.
• 🗺️ The diagnostic path then focused on tracing the red with yellow wire from the fuse box to the EBCM connector (X106).
• 🧐 Visual inspection of the harness revealed suspect areas with tape and zip ties, suggesting potential previous tampering or rubbing.

Locating and Repairing the Broken Wire

• 📍 After extensive searching, a broken wire was discovered within the factory harness, specifically the red with yellow wire.
• 🛠️ The repair involved cutting out the damaged section of the harness and using crimp and seal connectors for the repair.
• ✅ The harness was then re-wrapped with factory-style tape and secured with zip ties to restore its original appearance and integrity.
• 🌟 Post-repair, a fault scan showed no ABS light, and all systems were functioning correctly, indicating a successful repair.

Diagnostic Reflections and Best Practices

• 💡 The technician reflected on the diagnostic process, noting that checking the fuse first is a standard practice.
• 🎯 A more efficient approach would have been to check the large connector (X106) earlier or to investigate the suspect taped area immediately.
• 🔧 The video also discussed the limited utility of wire tracing tools in automotive applications, emphasizing visual inspection and understanding harness routing.
• 🚗 The prevalence of broken wires and corrosion in vehicles, especially in certain climates, was highlighted as a common diagnostic challenge.