P1562 — Replace Electronic Control Unit (ECU)

Causes

• Failed or damaged engine ECU (internal electronic fault)
• Corrupted or missing ECU software/calibration or KAM (keep-alive memory)
• Loss of power or poor ground to the ECU (intermittent battery connections, blown fuse)
• Damaged main harness connector or wiring (short, open, high resistance)
• CAN/LIN bus communication fault or module addressing/immobilizer mismatch
• Failed related modules preventing ECU validation (immobilizer, BCM)

Symptoms

• Malfunction Indicator Lamp (MIL) illuminated
• Engine may not start or may crank but not run
• Loss of engine management functions or severe drivability problems
• No communication with ECU via diagnostic scanner or intermittent communication
• Immobilizer or security warning lamp may be on
• Stored multiple communication and internal module fault codes

What to check

• Read all stored and pending codes and freeze-frame data with a quality scan tool
• Attempt to communicate with the ECU: check for module present and responding
• Verify battery voltage (12.4–14.8 V) and condition; check for recent low-voltage events
• Inspect ECU connectors and wiring for damage, corrosion, bent pins and water ingress
• Check fuses and relays supplying ECU power and ignition-switched power
• Verify good chassis and engine block grounds; perform voltage drop tests on power/ground circuits

Signal parameters

• Battery voltage at ECU pins: about 12.4–14.8 V with engine running
• Ignition-switched supply voltage present when key ON: ~12 V
• Ground continuity: near 0 ohms to chassis/engine block
• CAN_H/CAN_L idle voltages: ~2.5 V with differential signaling and active data traffic
• Module respond/heartbeat: periodic messages on bus when scanned
• Crankshaft position sensor and camshaft signals present when cranking (if applicable to communication)

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