NO Start??????

[Duramax Wannabe]

My 66 Duramax wont start (NO CRANK), the key on powers the start relays but the ecm/pcm wont ground them, this has been an intermitten problem for months, then one day the motor got sick and decided it did not need # 5? piston (left front of block) Replaced motor and now no start no crank nothing PLEASE HELP before i burn it?????????
Any info would be helpfull have checked and rechecked grounds, also the radio says LOC whats this?
P.S. Batteries were disconnected for about 3 months.

[rat4go]

With Allison? Check connection to NSBU switch on drivers side of trans. If ECM doesn't see Park or Neutral signal from this switch, it won't ground the relay.

There's a similar switch on a manual that indicates clutch is in before it will crank.

Good luck.