Remote start install help (Passlock)

I upgraded the remote start in my car ('01 Impala LS) to a 2-way unit and am having a problem that I suspect is Pass-lock related. My old starter (Primestart X10) was wired in before I purchased the car, so I rung out the harness and spliced my new starter at the harness for the old box. The new unit (Prostart CT-3400TW) works (as far as doors, trunk, no problems programming) but the engine will not crank. There is a code flashed on a failed start, but the code does not show up in either the install or operation manual. In diagnostic playback, I get a code "no tach cut-out", which I suspect is a code tripped because no engine crank = no tach signal. The ignition relays all click, but the starter will not engage. If the old system worked, I assume it would need a Pass-lock bypass, so I cannot figure out why the new unit will not work if the existing harnesses were not disturbed. Since I did not install the original and this is my first time dealing with remote start installation, I don't even know where to look to find the bypass, but I assume it would be on the ignition line. Can anyone offer some guidance with this one?

Hey I am having the same problem on my 04 impala ss, I have found that the ignition wires (both pri and sec) go to ground when the starter goes hot and therefore never seems to attempt to crank even though the starter wire has 12v.  I don't think that the relay module for my 791 is supposted to ground the ign wires !?!? I tried using 2 different 555ls Iborrowed the one from my 01 silverado with no difference.