I had a similar project a few years back with my Honda 1990 CRX. My tach broke so I wrote an arduino serial driver to read the working memory registers from the ecu.

We never thought to hit the automotive junkyard to find electronics we could play with. But [Istimat] was able to pull this working tachometer from an otherwise destroyed motorcycle dashboard. The … ...

Make Magazine's Arduino Section: Make Magazine's Arduino section is a huge resource for new projects, explanations, guides, and tutorials. This is the best one-stop location for Arduino beginners ...

An Arduino can be used to test the life of any battery with less than 5 volts, Boxall says. So, for a quick way to see how much juice your AAA, AA, C, or D batteries have left, build this Arduino ...