First I'm sorry for posting this question because I know its been up here a number of times. I haven't read anything like my problem.
I have a 1999 F150 4x4 with the 4R70W. I bought the truck and drove it home 300 miles and light never came on. Went to go to work in it 2 days later and the OD light tripped. I drove to work and once I got there I shut the truck off. Restarted and the light went out. About 5 days later the light the light came on again and I stopped a trans shop to pull the code and it came up as a P0781 shift solonoid. Came home read up on it.
Heres what I dont understand.
1: The truck runs and shift fine when the light is off. No hard shifts and shifts smooth thru all gears and no jerk on down shifts.
2: When the light is on the thruck upshifts fine and only jerks lightly on 2 to 1 downshift.
3: The light randomly comes on. It may come on once a day or a number of times a day. May not come on for 2 or 3 days or it may not come on for a few weeks.
I paid for a trans service and new solinoid just to be on the safe side. After the install the truck never trip a light 17 days after. Since that time of coming on that once which was 6 days ago it has only come on once since then.
I thought it could be in the lever and wiring harness from the lever down. Took dash apart and looked for worn wires. Didnt find any. One thing I have noticed is that my odometer in the gauge cluster goes in and out.

Any ideas? All help appricated and once again sorry for posting this question again.

 

It can't be the wiring in the shift column. It also can't be anything related to the odometer. If you have a code for the shift solenoid either the solenoid is bad or the wiring to the solenoid from the PCM is bad. It can only be one of those.

 

Thanks for the advice Mark. I have replaced the solenoid so I guess that leaves the wiring. I have the lower dash out. Can you point me to which harness or color code wiring I might look at without trying to trace it from the trans back. Or even a pin out on the ecm connector? Would be appreciated if you could.

 

I don't have any diagrams. I don't think any of the wires run under the dash. They should go from the trans to the PCM without entering the cab.

 

I have EXACTLY the same problem. Odometer and all. Any solution to this?

 

Check the main transmission harness, it comes up over the bell housing to the passenger side. most people mis-route this harness and it burns against the exhaust manifold. the harness will connect to a junction box right above the blower motor. You can unbolt the harness and remove it from the truck.

 

Hey shaggy1677,

Have you spoke with your Ford Dealer about this? Which model year F-150 do you own and what's its current mileage?

Nick