The map sensor on the pass. fender runs the factory boost gauge. The green wire is on that plug. Also check the vacuum/boost line connected to the map. If it's unhooked from the motor, no lights.
Not to hijack this thread. But if you have a 3 bar map will it change the way the LED tach reads. Mine is reading way higher than it should. Also if I need to wire up Fuel pump and boost controler, do I wire it up to that?