C1A91 — Chassis Control Module — Internal Fault

Causes

• CCM internal hardware failure (processor/memory/circuitry)
• Corrupted or failed module software/firmware
• Intermittent or low power supply (battery, ignition feed)
• Poor ground or corroded/loose connector pins
• CAN/LIN bus errors or excessive electrical noise
• Water ingress or physical damage to module

Symptoms

• ABS/ESP/traction control warning lamp(s) illuminated
• Reduced chassis control functionality or limp mode
• Loss of communication with chassis-related modules (ABS, ADAS, steering)
• Stored fault(s) in other modules referencing CCM communication
• Intermittent or permanent faults that may persist after key cycles

What to check

• Retrieve full DTC list and freeze frame data with a capable OEM scan tool
• Check for accompanying communication DTCs (U-codes) in other modules
• Measure battery voltage with ignition on and during cranking (should be ~12–14.5 V)
• Visually inspect CCM connector, pins and harness for corrosion, water, damage or displaced seals
• Check fuses and power feeds to the CCM
• Verify good chassis ground(s) at or near the CCM

Signal parameters

• Module supply/ignition feed: ~12–14.5 V (key on)
• Module ground: near 0 V (low resistance to chassis ground)
• CAN High/Low idle voltages: approx. CAN_H ~2.5 V, CAN_L ~2.5 V (differential ~0 V at rest)
• CAN differential during activity: ±1 V around idle (~2.5 V each)
• Message frequency: verify expected CCM CAN IDs/messages with OEM data
• Watchdog/reset events and internal error counters from OEM tool

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