Ford Mustang Forum - View Single Post - Electrical whizzes - help please
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post #12 of (permalink) Old 10-06-2013 Thread Starter
LandToSea's Avatar
Joined: May 2010
Location: West Palm Beach
Posts: 1,373
Originally Posted by 2012v6Pony View Post
You have the basic idea that you want to use a "switch" on pins 30 and 87 (to open or close the circuit) which will run the fan but that is a high amp (40 amp) circuit which is what burned up your jumper wire.

If you found a 40 amp switch and used heavy enough gauge wire (wire gauge will need to be at least what is running to the fan itself) it would work... but I doubt you will be able to find a 40 amp "switch" that's where the relay comes in...

The relay allows the high amp circuit to be controlled with a low amp switch (5 amp) on pins 86 and 85.

In the stock diagram pin 86 is hot 12v 5amp wherever the key is on (when the PCM is on) pin 85 is what the PCM is using to control the relay BUT you can't simply ground pin 85 (DO NOT DO THIS) without risking damage to your PCM.

So I guess I am not sure how else to explain (sorry I am not a very good teacher)
Could I use a switch like this?


40A Safety Switch DIN Rail 1 Pole Mini Circuit Breaker | eBay
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