Because it can allow the engine to overheat.
Car cooling fan control circuit.
Now take the power wire from your fan and connect it to the wire that is going through the firewall.
The fan as well as other apparatus draws too much amperage to be safe in the cockpit so it s kept under the hood.
The vehicle s pcm s function is to act as a ground to operate components not to supply power.
The ecu then triggers a check engine light to illuminate on the dashboard.
During the install christian shot.
P0480 means that the cooling fan 1 control circuit has a malfunction.
Or a failure of the fan relay or control circuit is bad news.
Get the 10 gauge wire and place it through the hole in your fire wall.
The temperature controlled switch is designed to turn the fan on when coolant temperatures reach 195 degrees and turn off the fan when temps drop to 185 degrees.
A switched terminal will be hot only when the key is on.
The fan may work but it only runs at low speed.
So now we have a wire that goes through the engine bay to the cabin of your car.
Which may not be fast enough to prevent overheating.
The engine may also overheat if fan speed fails to increase when additional cooling is needed.
The vehicles ecu has tried to control the cooling fan 1 and it has failed to operate or a fault was detected.
A constant power supply from the battery is present on a terminal in each of the relays.
On applications that have variable fan speeds.
On older fan circuits the thermostatic switch connects to battery power on one side and to the fan motor on the other.
This one turns on the fan when the circuit is closed.
Engine cooling fan issues.
The fan relays are nothing but a remote light switch.