I am going to wire the auxillary factory trans cooler so I can turn it on when I am under heavy load. Someone said to wire it with 10 ga wire and a relay. Seems like that fan should not draw that much current. Can't I just splice into the hot side and run it to the cab, thru a switch and back to the other wire. Then when the switch is thrown the fan runs and when off the thermostat is operational? Seems like 12 ga wire should be sufficient. Anyone know the amperage draw of that cooling fan?

 

If your cooler is already installed then 12-gauge will be fine, all you have to do is to connect your in-cab switch in parallel with the 2 temp sensor wires where it is mounted on the front side of the cooler housing.

The system should have been wired with a relay but Dodge didn't think so when they designed it.

When I replace the lines on mine I am going to wire it using 10-gauge wire and a relay.

Jim