91 z28. when wiring my neutral safety switch up with a mega shifter the instructions say that some vehicles have 2 additional wires that tell the ecm that its in park/neutral, and to wire these up with the switch an additional relay is needed. i understand how the relay would work in this situation, but it seems at tho i can just tap the ecm side of these 2 wires into the wire that is closed of the neutral safety switch. the neutral safety switch puts out a ground signal, and the ecm receives a ground signal when in park/neutral, so i should be able to do this. am i missing something to where i should not do this?

 

You are right, technically it is the same function (grounded switch in Neutral or Park).
The only difference I can see is that the starting circuit is not always grounde but can have power on it (when cranking) and also flyback spikes from the solenoid.

For that reason, I would not recommend using the starting circuit for the ECM input.
I would strongly recommend using the relay.

Hope this helps.
Lou

 

after running over my wiring diagrams again, you are absolutely right, i totally forgot about the starter running thru the wires. thanks for clearing that up for me, i'm going to run the relay. thanks.

 

when I did mine before I just connected the thick yellow and purple wires together and it worked as the loop it completed like it would be on a stock shifter

 

but that would let it start in any gear, i'd rather have a relay to prevent that.