I have a 2003 Ford F150 with a V6 4.2L with 5 speed Manual Transmission. Someone changed my clutch out one time and when they did it they put the wiring harness that goes from the ECU connector to the back 2 O2 sensors and the 2 sensors on the transmission itself. I was wondering if I could use an automatic transmission wiring harness to allow my speedometer and O2 sensors to work?

 

Unless you are absolutely sure there is a problem within the present harness , you could wind up creating addl problems in the process of replacing a good harness.