Please help, 99 Expy problems

[99 Expedition]

I have a 99 Eddie Bauer edition 4x4 Expedition. I started having trouble with the OD light blinking, and hard shifting. Had it tested and I was told it was the vehicle speed sensor (VSS) on the rear of the transmission. I replaced the VSS and for about 3 days it ran fine with no problems. Then the OD light started flashing again, hard shifting and the speedometer starting jumping around. This time I was told it was the ABS speed sensor on the rear differential. So I replaced it. Again it ran good for a few days then the problem came back. This time along with the flashing OD light and jumping speedometer, and the hard shifting cruise control stopped working properly. Had it tested and did a lot of research and came to the conclusion it was the solenoid pack in the transmission. So I changed the solenoid pack, new trans filter and fluid. Btw the transmission fluid was clean when I drained it out. This time it ran good for a couple weeks. Now when it's cold it will start off hard shifting, the OD light will start flashing sometimes but not every time. And seems to stop after it is driven for a few moments. But the speedometer is still jumping around, and the 4x4 light has started flashing. Cruise control is still not working properly. And most of the time if I stop and turn the engine off for a few moments then start it back up it runs fine. I'm not sure what it could be and would really appreciate any help I can get. I love my Expedition and just want to get it back to running as good as it use to.

 

[98EXPnSRQ]

I know this sounds lame, but I would disconnect the + battery cable and make connection with - battery post for a few minutes. This removes all power and resets the PCM. Reconnect, start and let it idle without touching the throttle for a few minutes. Then drive it very gently so it relearns. It doesn't cost anything to do and it can be a possible solution.

 

[99 Expedition]

Yea I tried that already. And for a couple days it runs good but then the problems come back. I believe there is a sensor on the transfer case, I was told could cause the 4x4 light to blink If it is going bad. So that is what I'm looking into now.

 

[stamp11127]

Check the wiring harness for burns or chaffing near the exhaust manifold and any place it comes into contact with metal,

 

[99 Expedition]

I chkd all the wiring, no Burns, no cuts. It all looks good. I just don't know what it could be.

 

[stamp11127]

Scanner time to monitor the vss signal. Is the signal dropping out or is the vref being lost? Can't tell until you monitor what is being sent to and from the ecm.

 

[98EXPnSRQ]

Yea I tried that already. And for a couple days it runs good but then the problems come back. I believe there is a sensor on the transfer case, I was told could cause the 4x4 light to blink If it is going bad. So that is what I'm looking into now.

Yeah, the position sensor is built into the shift motor. You have to replace the motor assembly. It's not too hard to do. After you change it out, do the battery disconnect / reset I mention above.

 

[99 Expedition]

I appreciate the help. I'm going to replace the shift motor ASAP. I will let us know how it goes. Hopefully this will fix my problem.

 

[Kermit]

So was it the shift motor?