99tahoe won't start

99tahoe won't fire.  The icm
received signal from pcm.  
Icm won't send signal to coil.
I've bought and have and the
icm tested before I left store
and tested it again after
bringing it back showed to be
good.  I have checked ground
it's good. I've got 12 volts to
coil and icm. I have 12volts
even when cranking. I've
check continuity on white
/black stripe wire from icm to
coil no signal.  I have replace
cam and crank senor
checked volt and signal while
cranking. Ohmed wires from
pcm to icm also on crank
senor.  No sercuity light one
code 1336 .but that's not
causing the icm not to send
signal to coil so it can fire.
I've checked voltage signal
and ground on all these
senors and they check out
good now why won't the icm
send signal to coil when
everything checks out. The
icm has been replaced
bought new oem parts like 4
of them from different parts
store.  Would the bcm if I
have one cause this no fire.
And I've had this problem
before and just one day it
started like 3 months later.  I
was pulling out of driveway
and it died. I just can't get the
icm to send signal to coil to
make it fire.  Is the a way I
could use a jumper wire to
help me find a problem