Having trouble with my 06 mustang gt. 4.6 engine, auto. Have changed cht sensor, cooling fan resistor, and all fuses and relays. Can jump the fan and it does come on. Will not work on low or high speed.......any suggestions?

 

The fan wiring under the BEC and at the fan connector tends to overheat and cause issues.

There is no manual control of "low" or "high" speed; the PCM controls which speed comes on.