Master Cutoff Switch Question - Ford Mustang Forums : Mustang Forum
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post #1 of 3 Old 03-27-2012, 07:29 PM Thread Starter
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Master Cutoff Switch Question

Okay Gents, I've done more searching than I'd care to do again to find the answer I'm looking for. I have a Vortech kit I'm installing on my 96 cobra with a trunk mounted battery. I know how I'd like to wire the car but am unsure of one thing revolving around the master cutoff switch required to track it. Below is a diagram I've found and am basing my wiring off of. The issue I'm running into is whether or not a Painless wiring Alternator Shutdown Relay is really necessary. I guess I don't see the point of it and am hoping someone has experience in this and can chime in. From what I've heard others say, it is required to prevent a voltage spike that could fry the ECM when the cutoff switch in engage. It is also used to prevent engine run on. The way I'm wiring the car puts the underhood junction block on the disconnected side of the battery thus killing all electrical in the car. So if anyone could shed some light on something that I'm missing or confirm that I'm heading in the right direction, I'd greatly appreciate it.

Sorry for the novel.

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post #2 of 3 Old 03-28-2012, 12:05 AM Thread Starter
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post #3 of 3 Old 06-10-2012, 10:35 PM
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That would work... but it would leave power to your alt, and it would leave the battery light on your cluster. which will drain the battery.. I have the same basic set up right now. I am buying a Sparco battery kill switch. this cuts down about 20 lbs of wiring. its worth the 60 bucks if you can wire it right.
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