Very simple there is only one exception to the rule and that is:

1996-2000 and 1996- 2001 Domestic primary does only those years

ALL other cartridges, Domestic or Asian or Euro, cover from the year stated to the

first year of computers in that car.

This is true for primary cartridges and troubleshooter cartridges.

example 1999 domestic primary, works for 1980 or first of computers -1999

example 1999 domestic troulbeshooter works from 1980 or first of computers -1999

Primary cartridges also do Generic OBDII mode, but this only gives very limited data and is general not usefull to help repair your car.

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