C1A86 — Steering Column Control Module — Internal Fault

Causes

• Internal electronic or processor fault inside the SCCM
• Corrupted or failed module firmware
• Water ingress or corrosion damaging internal components
• Over-voltage, thermal stress or physical impact to the module
• Intermittent or poor power/ground connection to the module

Symptoms

• Steering wheel controls (audio/cruise) non-functional or intermittent
• Stalks (indicators/wipers/lighting) operate incorrectly or not at all
• Steering angle sensor data absent or incorrect — stability/ABS/ESC warnings
• Instrument cluster or message center displays a steering column/module warning
• Steering lock or column adjustment inoperative
• CAN bus related faults or other modules reporting loss of SCCM communication

What to check

• Read all stored and pending DTCs and freeze-frame data with a dealer-level scanner
• Attempt to clear codes and re-run to see if fault is persistent or intermittent
• Visually inspect SCCM connectors for corrosion, bent pins, water ingress and secure fit
• Check related fuses and relays for continuity and correct operation
• Measure supply voltage at the SCCM connector (key on) and verify proper ground
• Check CAN bus presence at module: verify CAN H/L voltages and message traffic with a scope/diagnostic tool

Signal parameters

• Power supply: nominal ~11–14.5 V with key on; no large voltage drops during operation
• Ground: low resistance to chassis (typically
• CAN bus: CAN High/Low idle differential and common-mode within manufacturer spec; module should transmit/receive steering messages
• Steering angle/position message: present with correct update rate and valid values when steering is moved
• Wake/sleep signals: module responds to vehicle wake commands and transitions correctly

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