Suzuki (and Geo badged Suzuki) ECU diagnostics can be categorised into two very broad types, usually refered to as 'OBD1' and 'OBD2'. Prior to the adoption of OBD2 some countries had a mandatory requirement for On Board Diagnostics, others didn't. Most manufacturers did fit diagnostic interfaces and these were usually proprietary. The majority of Suzuki ECUs from 1991 onwards were fitted with a diagnostic link, a notable exception being the Swift GTi models.
The terms 'OBD1' and 'OBD2' are actually very specific to the US but have achieved common usage worldwide. In the US OBD2 was mandated from 1996 onwards, in Europe legislation required the adoption of EOBD (mostly compatible with OBD2) from 2001 for new petrol engined passenger vehicles through to 2004 for existing models of diesel engined passenger vehicles. Japan adopted EOBD in 2004, Australia adopted EOBD in 2006 and India is currently scheduled to adopt it in 2013. Of course manufacturers were free to adopt OBD2 or EOBD before the mandated dates so legislation dates only mean that vehicles introduced after those dates will meet the relevant specification, before those dates they may be OBD2, EOBD or proprietary. The primary interface on Suzuki ECUs is a proprietary format (generally still referred to as OBD1) and where an OBD2 or EOBD interface is also fitted, to meet legislative requirement, it is limited to the legal minimum. The official, and hugely expensive, factory scan tools, the Tech1, Tech2 and SDT use this propritary/OBD1 interface. The Suzuki specifications have not been made public but are available to aftermarket scan tool manufacturers with an annual licence fee being charged. OBD1 on OBD2 ECUs