97 4.6 Ext Cab Auto 4WD
Code P0503.

Truck runs in overdrive. If You push the button to lockout OD, fuse blows. Other times, normal driving, OD off light flashes.

Checked column wires for frayed wire, all ok there. Friend tells me either the OD switch, sensor in differential or sensor on tranny. I was also told to watch for fluxuation on speedo when light flashing. Needle stays where it should be, no variation.

Best course of action?

Thank you.

Jim

 

There is no sensor that can blow a fuse when the OD button is pushed. The only way that can happen is if there is a short to ground in the wire between the button and the PCM. You'll need to find where the short is and fix it.

You might also want to read the codes. When the OD light flashed a code was stored. I think that might be more than the OD button.

 

The short is most likley in the gear selector shift handle. You will need to pull it apart and check it.

 

I pulled the cap and switch. All looks ok there. As I stated in my original post, wires down the column look ok too. I guess I'll trace them to the end this weekend.

 

Did you pull the column covers off and check right where the wires go into the shaft itself. That is usually were they break.

 

Yeah, Pulled the column cover, all looks ok there. Gotta believe its near the tranny.

 

The wires from the shifter go to the PCM, not to the trans.