ALCL meaning in General ?

Assembly Line Diagnostic Link or ALDL is a proprietary on-board diagnostics system developed by General Motors before the standardization of OBD-2. It was previously called Assembly Line Communications Link or ALCL. The two terms are used interchangeably.

This system was only vaguely standardized and suffered from the fact that specifications for the communications link varied from one model to the next. ALDL was largely used by manufacturers for diagnostics at their dealerships and official maintenance facilities. The connector is usually located under the dash on the driver's side of left-hand drive (LHD) vehicles, though this location was not standardized.

For the assembly plant test system computer that was connected to this vehicle connector and known by the same name, see the article IBM Series/1. In the late 1980s the system was migrated to the ADTS system (ALDL Development and Test System) which utilized an industrialized IBM PC with custom interface hardware.