My colleague and i were going to fix a piece of equipment when suddenly the 05 6.0 just died.... No warning just boom died. I didnt wanna guess at the thing so i dragged it to the dealer with my 94 F-350 7.3 Mechanical Diesel
So they've been diagnosing the thing for a few days now. First the put a crank sensor in it nothing..... then they put a cam sensor in it nothing..... then they said they had to "Speak to their engineers" and they said it was a PCM related problem. They put one of those in and still nothing. Now i spoke to the tech in person and he now believes that the tone gear on the crankshaft, which remind you is on a keyway and just floats there has spun the keyway and TDC is reading wrong because the gear is not in place. He tried to pull the crank sensor out of the block and turn the gear with a screwdriver but he said it could have just siezed up.......
Without actually seeing the PID readings and DTCs (if any), it's pretty difficult to say what the problem might be. My guess as to why a crank sensor was installed would be if the SYNC reading failed to change from "no" to "yes" when the engine was cranked over, and/or engine cranking RPM was inconsistent. Typically, the servicing tech should be monitoring the following PIDs:
FICM_L: should read 11.0 to 12.0 volts at key-on/engine-off and remain steady while you crank the engine.
FICM_M: should read 47.5 to 48.0 volts at key-on/engine-off and remain steady while you crank the engine.
FICM_V: should read 11.0 to 12.0 volts at key-on/engine-off and remain steady while you crank the engine.
ICP V: should read 0.25 volts at key-on/engine-off and climb to minimum 0.8 volts while you crank the engine.
ICP: should read 0 psi at key-on/engine-off and climb to minimum 500 psi while you crank the engine over.
IPR Duty Cycle: should read 14.84% at key-on/engine-off and climb to around 50% as you crank the engine over.
FICM_SYNC: should read "NO" at key-on/engine-off and change to "YES" when you crank the engine over.
SYNC: should read "NO" at key-on/engine-off and change to "YES" when you crank the engine over.
V_PWR: should indicate around 12 volts at key-on/engine-off and drop to no lower than 9.5 volts while cranking the engine over.
RPM: should indicate around 175 to 200 as you crank the engine over. Any slower, and it's not cranking fast enough.
If any of the above PIDs are outside of what I've listed above the vehicle will not start. But based on the information you've provided and the way you're desribing it, I would be leaning more towards your engine harness that seems to be causing your issue. In the few years I've been wrenching on 6.0Ls, I have yet to replace a PCM. That's not to say it's not a possibility though. The crank sensor tone ring is NOT keyed to the crankshaft. It IS part of the crankshaft, meaning if the tone ring is an issue, the entire crankshaft would need to be replaced.
By "oil leak", it's not an external oil leak that is being referred to regarding the STC fitting. Rather, it's an INTERNAL high pressure oil system leak that is being referred to (refer to ICP data above). If ICP fails to reach 500 psi, the FICM will NOT fire the injectors. Typically, on 2005 and up model years the STC fittings have been prone to blow out of the high pressure oil pump outlet, causing an internal high pressure oil system leak.