Tech 1 is an earlier handheld diagnostic platform used on GM and Opel/Vauxhall vehicles; a Suzuki-specific application also operated on the tool. The brand application, cartridge, leads and adapters determine coverage. It was followed in GM's diagnostic-tool family by Tech 2; the generations can overlap in coverage, so no single model-year cutoff should be assumed. GM Service Training Center Tech 1 guide; Opel/Vauxhall C20LET workshop manual.
Tech 1A and cartridge applications
Vetronix's GM Chassis Application manual describes Tech 1's original introduction in 1984 and Tech 1A as an updated version released in 1989. The same manual notes the retirement of both in 2003; this is a vendor timeline, not a universal vehicle-coverage date. Vetronix GM Chassis Application manual.
The Opel/Vauxhall C20LET manual lists a Tech 1, a 10-pin adapter for the Calibra diagnostic connector and an “Opel/Vauxhall 87-94 ECU GB” program module. The numbers in that module's name are not proof that every vehicle or system from those years is covered. C20LET workshop manual, special tools.
Suzuki ECM 6.0 documentation describes a separate mass-storage cartridge application for engine and, where applicable, automatic-transmission powertrain diagnosis. The manual excludes North American OBD-II vehicles from model year 1996 onwards from this application; use its own model and ECU table. Suzuki ECM 6.0 operator's manual. See Suzuki diagnostic systems and Opel/Vauxhall diagnostic systems.