| A little while back I began constructing an OBDII scanner for my parents' cars. I used the plans found on scantool.net. Both of them have GM vehicles so both cars use the same OBDII standard, which is VPW. The scanner looks identical to this one: 
While I could have just bought the one from their site, I like building my own circuits so I printed out a reversed image of the trace layout on a laser printer, ironed the traces onto a copper clad board, and then used copper etchant solution to dissolve all the copper that wasn't protected by the toner from the laser printer. Then I drilled the holes and soldered in all the components. I completed most of the circuit a couple of weeks ago but I still needed the cables that fit the OBDII plug, so I ordered them. This morning the USPS guy delivered the cables I needed to hook it up, I finished soldering the board and plugged it in. Pretty neat. It tells me the readings from all the sensors and any error codes that the ECU is giving. It's really handy to have such a scanner since you can see what all the sensors are reporting. If your car isn't running right, it's usually hard to tell which sensor is the culprit, since a bad sensor looks identical to a good sensor. This board, being based on the Elmscan chip is a pretty universal design and many people write software that is compatible with it. You can get software that works in Windows, Linux, PalmOS, Pocket PC, and even DOS for old laptops. Right now I'm using an laptop with Win95, but I'll probably get a cheap Palm in the future for convenience. While this scanner won't do anything for my Z since only 96 Z's are OBDII (and even if I had a 96 Z, this scanner wouldn't work on it anyway since Nissan uses a different OBDII standard than GM), it's a stepping stone to make a scanner for my Z. I have the schematics for a 1990+ Nissan ECU > serial port interface and I'll probably get started pretty soon. While it won't be as capable as the Nprobe or Zemulator, it won't be nearly as expensive either. I'm just looking at something to help troubleshoot problems if any arise, and it'll only cost me about $50 to make.
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SZR: It's alive (OBDII Scanner) - 
