Greetings solaralexx,
Welcome to the GMT400 forum!
To answer your question, the fanout from splice S161 will allow you to implement a kill switch
that will disable fuel delivery at multiple levels. All the starter noise you could want yet
no fuel delivery
plus no spark either. (!)
Of course, in order to take advantage of this fanout, you will need to insert your kill switch
in series in between the 20 Amp "ECM 1" fuse and the splice. This fuse is located in the
Underhood Fuse Block:
You must be registered for see images attach
I went to the '97 FSM and scanned it for all instances of the occurrence of 'S161'. (There were 20.) I've attached the most relevant pages below:
* 1) The 1st attachment shows the power sent to the 8 injectors. In normal operation, with the key on +12v power is constantly
applied, and the VCM grounds the fuel injector(s) sequentially in the firing order so that electrical current can flow/fuel to spray.
Removing power from S161 disables all fuel injector operation.
* 2) The 2nd attachment shows S161 feeding power to the CKP, Coil, and Ignition Control Module. Without the signals from
the Crankshaft Position sensor, no fuel injection triggers from the VCM will be sent. Also, there's no power to the
Ignition Control Module and Coil, so yet another layer of no start due to no sparks delivered to the spark plugs.
* 3) The 3rd attachment shows S161 feeding power to the VCM.
EDIT: Note that the "Hot at all times" power on the far left of the page is
undisturbed, so the long term trims and emissions monitors will continue
work properly across driving cycles.
*4) The 4th attachment is where the physical location of S161 is described.
****
If it was me, I would intercept the wire from the ECM 1 fuse to S161 in the middle of the run, and
I'd go to the trouble to use the same color code wire (courtesy of a Treasure Yard donor) in order to
make the addition look as absolutely factory as possible. My '99 C2500 also did not come with air bags,
but as noted in another thread the air bag/no air bag steering wheels look almost identical. (minus a small logo)
So again Skylark's idea to use a factory air bag switch is perfect, especially with being able to remove the key
at both switch positions.
****
Disabling just the CKP power would prevent starting due to missing reference pulses for Ignition and also no fuel injector pulses.
Disabling just the Ignition Control Module would prevent starting.
Disabling just the Coil would prevent any starting due to missing high voltage spark generation.
Disabling just the power to the fuel injectors would prevent any fuel delivery.
Disabling just the VCM power prevents engine operation. And also won't drive the fuel pump relay.
But a kill switch in series between the ECM 1 fuse and S161 disables
all of the above.
But the starter will crank. Fruitlessly. But it will crank. :0)
And in this thread we've given the GMT400 community not one but 2 different ways to implement a kill switch.
The first is no starter cranking. And the second allows cranking, but no engine firing.
Hope this proves helpful.
Cheers --