Review on Enhanced INNOVA 3145 Ford Digital OBD1 Code Reader: Optimize Diagnostics for Your Ford Vehicle by Jack Duncan

Slight learning curve but the book has very good step by step instructions along with all the codes. Contains steps to run various tests. I bought this because I absolutely had no way of counting the number of times the engine light was flashing, or using a voltmeter with a "jumper" test. You will need an extension to perform various tests while the engine is running (e.g. apply brake/spin wheel) The test port is located in the engine area on older vehicles, not under the driver's dashboard. When you buy this tool you probably have 16g wire and spade/socket connectors. Save $30 and just make one. (see image). Haven't been able to do an engine cylinder balance check yet, but I think I am. In an older car I found amazing peace of mind as all tests were done and everything came back. with "ones" indicating that whatever this thing tests is ready to go.