Thanks for the information on the mounting of the tester! I got it put together & tested it. With the ignition on position 1&3 for the 201 I got a single flash. Looking at the code list it saying no trouble. I would have thought it would have some bad boys stored from previous issues? I tested with ignition switch in on position. It showed on or in the engine run idle speed. I presumed from reading it either one is acceptable for testing??