Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I'm working on a '07 Nissian Quest 3.5L I'm diagnosing a intermittent no start, everything reads as should please look at picture to condemn the reason, a portion of metal missing off trans housing ?
You must see the crank signal on a scope first, and if that's wrong, then worry about that cracked trans housing. It should go from 12 volts to 0 volts in amplitude.