Autodiagnos A1004‑2 is an automotive multi‑tester used for diagnosing ECUs, reading DTCs, and performing voltage, current, resistance, and continuity tests on OBD1/OBD2 vehicles. Common failure points include a dead or weak internal power supply (often due to a failing main fuse or regulator), degraded USB/serial communication ports that lose connection to the host PC, and worn or corroded test leads that produce unreliable readings. For initial troubleshooting verify the unit’s 12 V input with a multimeter, inspect all connectors for corrosion or loose contacts, and run a self‑diagnostic routine (if available) to confirm internal firmware integrity before proceeding to deeper component checks.[oss-gpt-20b]