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Fan Overide switch Late Model

FordGuy

NAXJA Forum User
Location
San Clemente, CA
Yes I tried searching first! I have a 2000 XJ, I want to install a switch to override my Aux Fan. I want to do this because currently my Trans Cooler is mounted in front of the Radiator to take advantage of the Mechanical fan, Unfortunately this blocks a lot of air flow. If I move it to the other side it greatly improves the air flow and if I can override the Aux fan when Crawling it will cool the trans. My Idea is that if I tie into the ECU fan wire and install a Diode, and then intall a switch wired after the new diode, would this cause any issues I am not counting on.
 
My thoughts are why cant you just tie into the wire that goes from the factory ECU to the Factory fan relay, install a diode in front of the new wire so there is no feed back to the ECU and eliminate having to install a second relay etc..????
 
I just dropped a relay and 10 gauge wire under the hood. spliced B+ into the fan hot lead off the harness, wired the relay to a switch and .... done. When the new switch is off the fan operates normally, when I want it on i flip the switch. The new switch is wired in parallel so no voltage issues.

my $.02
 
DaffyXJ said:
I just dropped a relay and 10 gauge wire under the hood. spliced B+ into the fan hot lead off the harness, wired the relay to a switch and .... done. When the new switch is off the fan operates normally, when I want it on i flip the switch. The new switch is wired in parallel so no voltage issues.

my $.02

That was my first thought because of no ECU issues, then after thinking about it, is when I asked myself why not just use the factory relay and ECU feed with a diode in-line on the ECU feed. It eliminates all but one wire. Just trying to find someone to tell me if I am missing something because it is a ultra simple solution.
 
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