So, you want to talk to your car's computer? OBD II is the standard protocol (On Board Diagnostics v2). As of about 1996, most all cars use this protocol, and also have the standard OBD II connector and hardware interface. Typically the connector will be inside the car, under the dash or behind the ashtray, someplace like that. The device your mechanic will plug into it is called a "Scantool". Some manufacturers of these include Actron and Snap-On.
The standards are documented in SAE (Society of Automotive Engineers, http://www.sae.org/) publications SAE J1978 (OBD II Scan Tool) and J2201 (OBD II Scan Tool Universal Interface) and a slew of supporting documents. I see on their website they are selling a book with a collection of these ("SAE On-Board Diagnostics for Light and Medium Duty Vehicles Standards Manual") They are not trivial to interface to.
Prior to OBD II, there was a multitude of "standards" and you had to get a different scantool, or a different interface module, to deal with each of them. Each vehicle manufacturer rolled his own. And of course, back in the dark ages, primitive on-board computers would blink dashboard lights and stuff like that to read out codes. ("Codes" in this context stands for "Engine fault codes" that describe specific failure conditions.)
It's amazing what data you can get with OBD II: current RPM, speed, status of various systems, temperatures, pressures, flow rates, and voltages in various parts of the engine and drivetrain. Have fun, I hope you're able to get something going.
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So, you want to talk to your car's computer? OBD II is the standard protocol (On Board Diagnostics v2). As of about 1996, most all cars use this protocol, and also have the standard OBD II connector and hardware interface. Typically the connector will be inside the car, under the dash or behind the ashtray, someplace like that. The device your mechanic will plug into it is called a "Scantool". Some manufacturers of these include Actron and Snap-On.
The standards are documented in SAE (Society of Automotive Engineers, http://www.sae.org/) publications SAE J1978 (OBD II Scan Tool) and J2201 (OBD II Scan Tool Universal Interface) and a slew of supporting documents. I see on their website they are selling a book with a collection of these ("SAE On-Board Diagnostics for Light and Medium Duty Vehicles Standards Manual") They are not trivial to interface to.
Prior to OBD II, there was a multitude of "standards" and you had to get a different scantool, or a different interface module, to deal with each of them. Each vehicle manufacturer rolled his own. And of course, back in the dark ages, primitive on-board computers would blink dashboard lights and stuff like that to read out codes. ("Codes" in this context stands for "Engine fault codes" that describe specific failure conditions.)
It's amazing what data you can get with OBD II: current RPM, speed, status of various systems, temperatures, pressures, flow rates, and voltages in various parts of the engine and drivetrain. Have fun, I hope you're able to get something going.
-Th