Hello all,

I recently purchased a 2005 f-150 4x4 with 115,000 miles. The truck is in overall great shape but does have a mysterious transmission issue i have been chasing for over a month. The truck runs and drives great aside from a occasional rough shift. The overdrive light flashes and the monitor displays "trans fault". I have had the truck to a few different mechanics including the local Ford dealership. It pulls p0702. The truck will manually shift into 4x4 but it will not engage by using the switch. I have replaced: Trans wiring harness, checked all fuses, dropped pan and replaced all wires, nuetral safety switch and a few other misc. parts.

I am at a loss with what to do next to solve this problem. Any insight would be much appreciated!

Cheers!

 

When's the last time the codes were pulled and reset. Does the trans fault stay illuminated all the time. About the first thing we need to figure is the fault happening constantly or intermittently. The problem could be in the harness or main computer/power or ground issues but before you check those see if the code is constantly happening.

 

Thanks for the feedback,

I have cleared the codes multiple times, after clearing the code and starting the truck it takes about 5 seconds for the trans light to come on, it also makes one loud beep when the light comes on.

It is consistent when driving the truck.

 

Thanks for the information helps a great deal. I'm going to see what I can access for wiring diagrams. one thing you can do before you do any voltage checks if you haven't already is take a close look at the harness between the computer and the trans case connector, look mainly at areas that see a lot of heat and vibration that's most likely were you'd find a wiring issue. Let me see what diagrams I can get and I'll repost.