1996 chevy 3500 ign kill

I have a 3500 HD with a 7.4 in the shop that I need to put a mometary engine kill on. I am using a momentary sw to a relay to interupt a wire. My question is what to interupt. I am thinking Ign 1 (pink wire) and leave the others hot. I would like to do this all underhood, and I have found the the pink wire fom the Ign sw feeds to the ECM 1 20A fuse which then feeds to coil, coil driver, injectors, VCM, and Crank pos sensor. Is it ok to mom interupt this, and leave the others hot?

If you are only going to activate the circuit once in blue moon it might be OK. If you intend to do it more often, then this can cause serious damage to the engine and exhaust. The fuel mixture gets screwed up and GM has actually issued service bulletins warning against ignition interupts. GM says that even adding a relay to the pink ignition circuit can lead to momentary circuit interuptions and premature catalytic converter failure. The contacts inside the relay can actually open for a fraction of a second over bumps and play havic with the engine computer. From a safety standpoint, you should only use a starter kill circuit. If an ignition kill were used it could accidentaly activate while driving and cause an accident. You would be held lible.sparky

Thanks, This is a safety feature for this truck, they want to use it to remotetly kill the engine in case of emergency. (service truck) I wired one for them before and just put a sw in the pink wire going to the coil (80's chevy) If it takes out the injectors also, how could it cause a problem? Any other suggestions on how to do it? I did pull the ECM 1 fuse while running and it kills it right away, then whenreplaced it restarts and I show no codes on the ecm.

If the ignition circuit goes dead for a fraction of a second then so to does the high voltage ignition spark to each cylinder. The fuel continues to each cylinder and is not burnt. It then gets exhausted to the catalytic converter wherein it can then be combusted by the hot gases and causes premature failure to the converter. I am not makeing this up. It comes straight from a GM service bulletin regarding adding aftermarket alarms. GM says if an alarm is to be installed, then only hook up a starter kill feature. GM engineers spend a ton of time researching problems and won't document problems unless they can prove what is happening. A relay has mechanical moving electrical contacts inside it, that with time and vibration can begin to wear and occasionaly open over bumps etc. You should still be very concerned with the liablity issue. Nowadays people will sue over the most assine things. sparky