ODB-II Information

Daniel Burk ws6transam at voyager.net
Sun Dec 29 18:48:18 GMT 1996


Felix:  There exist two different hardware protocols for OBD-II.

One is a pulse-width modulated serial system and the other is a 
variable-pulse-modulated system.  GM and Chrysler use one system and Ford 
uses the other.

Technically, if you build a scan tool to do both protocols, the software 
is the same.

There exist Parameter IDentifier codes that are standard for scan tool 
use, but the individual PID's such as injector pulse width probably 
change from car to car.

You really need a copy of SAE HS-3000, which is updated for 1996.  This 
is the SAE book that outlines the OBD-II protocol, inclusing the pin-out 
for the connector.




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