P1628 — Powertrain Control Module ECM TCS Any Line Communication Error

Causes

• Faulty or loose connector at PCM/ABS/TCS module
• Damaged, corroded or shorted communication wiring (CAN/LIN/K‑Line)
• Poor battery or module power supply (low battery voltage, blown fuse, bad ignition feed)
• Bad ground at PCM or TCS/ABS module
• Faulty TCS/ABS/ESC control module or PCM/ECM
• Intermittent connection due to water ingress or corrosion

Symptoms

• Malfunction Indicator Lamp (MIL) or warning lamp illuminated
• Traction control / TCS / DSC warning light on
• ABS warning light may also be on
• Loss of traction control or stability control functions
• Reduced engine or driveability functions if PCM enters a failsafe mode
• Stored communication and module‑specific codes in scan tool

What to check

• Use a capable scan tool to read all stored and pending codes and freeze frame data
• Check for additional U‑codes (network communications) that identify bus failures
• Verify battery voltage at rest and while cranking; ensure good battery condition
• Inspect fuses and relays for PCM, ABS/TCS and communication bus power
• Visually inspect connectors to PCM/ABS/TCS for corrosion, bent pins, or water damage
• Inspect wiring harness along route between modules for chafing or physical damage

Signal parameters

• CAN bus typical idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive). Dominant state produces a differential of ≈ 2 V (CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V) — values are approximate
• LIN / K‑Line: single wire buses generally idle high (pulled up to battery voltage) and switch to low for frames — behavior depends on vehicle wiring
• Expected: steady recessive levels when bus is idle, regular packet frames when engine is running; long periods of silence, constant dominant state, or random spikes indicate faults
• Use scope or CAN bus analyzer to confirm correct waveforms, bus voltage levels and presence of packets from PCM and ABS/TCS modules

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