Ok I wired the P01 Green #10 wire to the tach signal wire on my 95 Volvo 940 and nothing happens on the tach. Drove by the shop this morning because I had a pack of resistors in my electrical cart, and did the resistor mod after I went to the junkyard and back. Spent some time ironing out a few other issues with the wiring and cooling system started it up and stuck the fuse in for my tach boost 12v source and nothing. After fooling around I stuck the fuse back in and watched the tach as I cranked the car over so the tach climbs upon startup to around 1700 rpm then nothing. I tried this 4 times, same thing. MY reasoning is that if I were to determine a certain ON/OFF pulse on the boosted signal it would work once set at the correct rate. I do not have a helper to watch the tach for me but I may try this tomorrow. Stick blades in and try to regulate the pulse with two jumper wires just to see if I am on to anything or not. There are signal translators out there but I am not going to jump the gun just yet. Any type of opinion or suggestion for a good device would be appreciated.