Battery in the Trunk

[Ron Ward]

Re: Battery in the Trunk

Beagle,

You are quite welcome. I never mistook you as being a smartass. There were great questions being asked and I wanted to make sure they were answered properly. Good luck with your projects!


Ron

[CTX-SLPR]

Re: Battery in the Trunk

On an EFI car, is cutting the power to the ECM like turning the switch to off an acceptable way of shutting down the engine?

[Ron Ward]

Re: Battery in the Trunk

On an EFI car, is cutting the power to the ECM like turning the switch to off an acceptable way of shutting down the engine?

For the purpose of ensuring the longevity of the ECM, probably not. But remember, this is a safety switch, to be used in times of emergency. I wouldn't recommend using this switch on a regular basis. However, if the car is into the wall and the engine is running and the safety crew wants to shut it down, the ECM is their least concern.


Ron

[Falcon67]

Re: Battery in the Trunk

On an EFI car, is cutting the power to the ECM like turning the switch to off an acceptable way of shutting down the engine?

No. The car needs to be electrically dead. The idea is that if you're wadded up against the wall or whatever, power to the car can be killed to reduce the likely hood of a fire caused by a short. All power - no lights, nothing.

[CTX-SLPR]

Re: Battery in the Trunk

Well yes pull the positive battery lead too but to keep engine run on killing the ECM power just like you turned the key to off.

[Falcon67]

Re: Battery in the Trunk

The reason the cars with alternators continue to run is they forget to re-route the big 10-gauge wire from the back of the alternator to the positive side of the battery. You are correct. If it is not re-routed, it will complete the circuit through the fusebox and keep the alternator field energized. If you read the NHRA rulebook carefully, it clearly states the cut-off must be on the positive cable and that the switch must cut off ALL current.

Ron

Note - this works, except now you have a continuously hot 10 gauge wire running through the car. And if the regulator is faulty, the car might be electrically live again. And 10 gauge is a little small for today's alternators, 8 or 6 is probably more like it. At least put a mondo fuse on it.