OBD was mandated by California in 1991.
Come 1996, it was standardized and then required by the EPA/Federal government for all cars sold.
As standards dictate, cars before 96 may not be reliable to decode.
PROs OBD2 made mechanics life simpler. being able to look at standardized data streams so you know what the values are…
Cons… some techs if they don’t find a code … don’t know where to look or what to do …
reading codes and replacing parts is not the usual or proper way to do many things. reading the codes… then looking at the live data to verify the device is not functioning as intended… but a good tech also checks powers and grounds to the device…
guess what… if you loose power or ground… you may not set a code on some devices…
OBD1 General motors had codes starting in 1981 maybe slightly before that in california… in 1982 you could with a crazy expensive scan tool actually look at live data stream…
cadillac did not need a scan tool starting in 1984 or 85. you could use the climate control buttons…
having an OBD1 scan tool was expensive to get all the various connectors and books… the OTC monitor 4000e in 1988 was $1500 bucks. and each cartridge was over 500 bucks. the import cables were a grand… and you needed 2 cartridges for 500 bucks each every other year… almost killed my boss when i ask him to buy one for the shop… i was part time. got on the mac tool truck . how much is the monitor that wayne wants… $1500 bucks… he grabbed his chest and fell off the tool truck. the tool guy felt so bad he did not even ask for that weeks payment…
when the mitchell computer info guy showed up… ill haul away all those old manuals… everything you need is in the computer… only hundreds of dollars a month… i leaned in… said… how far back does it go… 1982… look in the shop… how many 1982 or newer cars do you see… this was 87. … what happens if we miss a payment… its shut off… my boss the next month bought a wall full of mitchell manuals… they don’t expire if you miss a payment.
this is a small sample of OBD2 data that is available…
https://i.imgur.com/4zFXFFl.jpg
this is what was available in OBD1 in GM…
https://i.imgur.com/oIsOKlj.jpg
one of the few OBD1 and OBD2 scan tools that actually give GM OBD1 live data is the Bosch 1300 scan tool… most of the others only give you check engine light codes… that is fairly worthless to do other than aim you in the right direction…
Cons… some techs if they don’t find a code … don’t know where to look or what to do …
I don’t think it’s a fault of a system that often gives clear code that often points to the part that needs replacing.
Besides OBD1 and all manifacturer specific scan tools were already there. So without OBD2 we would have even more expensive scan tools only for the single make. And maybe manufacturers would even make them in a way that they don’t even actually allow you to diagnose a problem. Just tell you what part (they think) you should replace without giving any code setting criteria etc.
Unfortunately we are again already heading that way…
Pre OBD2 was not standardized and requires a tool that could communicate with that specific vehicle, often even a different connector. OBD2 standardized the connector and the communication protocol.
