Sorry for not checking in on my own sight. To answer Gregger. The OBD II tool that I have will erase simple faults. Maybe more, but I suck at ANY program logic no matter how simple. Moving on... I went out to the shop and realized that the few times I”ve
used the reader the cars were not running. I tried the test again and cleared the fault. Again. The code was P1690. I cheated and called a friend who owns a repair shop. He’s got a couple of expensive machines. The snap-on machine called the code a error caused by a “weak, or loose connection “ it goes on to “check the connection on the instrument cluster”. I remember one of the Captains mentioning this! Thanks to all of you. A will lift the tank and reconnect and look for oxidation at connection points. If anyone comes across other causes please send me a PM.