U2198 — Lost Communication With Control Module

Causes

• Open or shorted bus wiring (CAN/LIN/other vehicle network)
• Poor or missing power or ground to the affected control module
• Corroded/damaged connectors or pins at the module or splice points
• Failed control module (internal electronics or software crash)
• Missing or incorrect network termination (open/shorted termination resistors)
• Intermittent wiring fault (chafing, intermittent short to battery or ground)

Symptoms

• MIL or network fault indicator illuminated
• One or more systems disabled or operating in limp/fallback mode
• No data or stale data from the affected module on a scan tool
• Multiple U-codes referencing the same network or module
• Intermittent operation of features controlled by the affected module
• Instrument cluster or displays showing communication errors or blank

What to check

• Read all stored and pending DTCs with a capable scan tool and note freeze frame/occurrence
• Check for other U-codes on the same network (CAN/LIN) to identify affected segment
• Visual inspection of wiring harnesses, connectors, grounds and fuses for damage or corrosion
• Verify battery voltage is within specification and battery terminals are clean/tight
• Inspect module connector pins for bent, pushed-out, or corroded pins
• Check fuses and relays supplying the module power/ignition circuits

Signal parameters

• CAN bus idle (recessive): ~2.5 V on CAN_H and CAN_L, both near 2.5 V
• CAN dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (differential ≈ 2.0 V)
• Termination resistance: ~60 ohms measured between CAN_H and CAN_L across the two termination points (two 120 ohm in parallel)
• Low bus current; no short to battery or ground on either CAN line under normal conditions
• LIN: normally idle pulled to VBATT via pull-up; wake pulses present when active (if used)
• Module supply: battery voltage present at module power pin with ignition in required state, ground

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