OBD II refers to the On Board Diagnostic port that all new vehicles use to monitor their important functions. I decided to invest in an OBD reader after my truck's "Check Engine" light illuminated, and my local dealership wanted $90 just to read the trouble code. While I routinely use this dealership for service, but I thought that was way too much money for a 15 minute job. The trouble code turned out to be a simple evaporation system error caused by my fuel cap. I'm glad I didn't spend $90 just to find out my gas cap was loose.

After researching several consumer OBD readers, I decided that OBDAll-in-one had the most comprehensive and cost effective reader on the market. They use the newest ELM chip, which will work with almost every vehicle that has on board diagnostics. Their OBD kit contains all the software and cables required, and costs only $100. It's well worth the price, as most dealerships charge $90 per hour for even simple diagnostic work.

The kit from OBD2 All-in-One. Only $99.00 and includes all the cables for connecting to a serial port.	The OBD scan tool uses the ELM 327 chip which supports all the popular OBD protocols (PWM, VPW, ISO, KWP200, and CAN)	For connection to my PalmPilot, I use the serial HotSync cable, a null modem adapter, and a gender mender. There are also pre-made Palm cables available.
The Palm is ready to connect to my truck. This is the correct way for connecting a Palm device using the Palm serial cable.	Connected to truck and reading the sensor data using OBD Gauge for PalmOS from Dana Peters.)	Close up of the screen while graphing sensor data. There are 4 screens of sensor data that can be customized.
Now using the software to read any diagnostic codes.	As you can see, there are no codes and the CEL light is off.	For even more details you can also connect directly to a PC, and use software such as PCMSCAN from Palmer Performance Engineering.
Here's the same gauge screen, but I changed the reading measurements to US standard.	The software also allows you to see the raw OBD data in chart form.	PCMSCAN also displays the fuel mappings, so you can see the effects of ECU programmers or chips.
There are also free programs available, like OBD2 Crazy. These are great for quick code reading.	The OBD connector uses a right angle cable, so it doesn't protrude out very far.	I located the OBD reader inside my dash in a big space directly under the steering column.
For now, the cable is tucked under the console and Velcro wrapped to the Arkon PDA mount. I didn't want to drill holes for this installation.	The Arkon cupholder PDA mount is the perfect height and angle for my PalmPilot display.	Here is the display showing real-time engine data.
Here is the display showing real-time engine data.	Last picture showing the display from the passenger side.

I routinely use my scanner to check engine problems, and monitor key engine functions. The OBD info is far more accurate than the "dummy" gauges Ford installs in their trucks.

In order to decipher the various codes that appear on the OBD reader, I use the Ford OBD code database that was compiled by John Griggs. He wrote an excellent little Palm OS based database that works great for Ford Ranger CEL codes.

For more info on OBDII and OBDII readers, I've added some links: