The ET97 is not for your car. It is for you. Every vehicle contains a second electrical circuit—not grounded to the chassis, but to the driver’s nervous system. The ET97 reads that circuit. What you call “check engine light” is often just a mirror of your own inflammatory load.
Since Mac Tools removed the ET97 from their official support portal in 2018, you cannot download it directly from mactools.com . However, three reliable sources remain: Mac tools et97 user Manual
The Mac Tools ET97 is a professional-grade Digital Multimeter (DMM) designed primarily for automotive and general electrical troubleshooting. It is built to withstand the harsh environments of automotive repair shops while providing the precision required for electronic diagnostics. It is capable of measuring AC/DC Voltage, DC Current, Resistance, and testing diodes and continuity. The ET97 is not for your car