Topic: Massive Voltage Drop

[bkalasin]

Anyone have any ideas as to why I would have a massive loss of voltage (eventually cutting off the engine) while jumping a wire off my harness straight to my coils? Have a suspician my kill switch is dead / wired wrong. Drained battery (meter reads 12 volts with the key off but I was working on the lights with the engine off) would be my first guess, but maybe I'm missing out on some vital component by jumping the wire straight to the coils?

[Dennis]

Not sure what you are doing.
A defective battery can read 12 volt and drop to nearly nothing with a moderate load on it.
Are you sure your battery is good?

[timelord]

Two causes.

1. your battery cannot hold the charge
2. you have a short circuit somewhere

Simon

[SteveD CB500F]

If your battery is good, a voltage drop big enough to stop the engine (say down to 5 volts) can only be caused by massive current drain! (check for smoke!).  This current must be going somewhere. Iif you are using standard wire, such current would melt it.

I've seen this on my son's Fiesta.  The starter was shot and the drain on a new battery dragged it to 5 volts (with fumes coming from the battery breather) - on a car this is about 300A.