Just to confirm...running the wire lead to ground will cause the fans to run 10 minutes after the ignition is turned off but only if a threshold temperature is reached on the engine (can't recall now exactly what it is). So you don't have to worry about the fans running EVERY time you start your car.

As mentioned, if your battery is good there should be no problem and it does help a bit with underhood temps in the summer. Before moving to a PFC I used it for several years (through a switch so I could disable in cooler times) with no issues.

Im putting in new fans but theres two wires on the new bl and blue 4 on each old help i know black is ground and blue is hot on the new fans

its a 93 fd

on my 93, there was an extra harness inline with the relays that pretty much just shorted batt supply and ignition supply, so that fans would run with ignition turned off. if you remove this harness and plug straight into the relays, they wont turn on without the key turned

mybadrx7, BLK and BLU/ORG are ground, YEL/WHT and RED/YEL and WHT are 12V to fan