HI guys, I have a 2000, xlt, f250, psd, auto, 4x4, regular cab, it has the electric shift motor on trans case. The 4x4 was working great at the begining of winter and now it will only engage into 4 high and 4 low. It would not switch back, I took the motor off and switched back to 2 high manually and it again would go into 4x4, but wouldn't switch back to 2 high. I bought a new shift motor and put it on in 2 high and it does the same thing. I took the switch out of dash and put it in my excursion and it switches as it should, fuses are all good, wires at motor look ok no cuts or signs of corrosion, What else is there? THANKS

 

Does anybody have any suggestions at all?

 

I'm not a mechanic at all... but just reading your post it seems like it's not a SENDING error, but a RECEIVING error.

If the motor is good, wires and fuses good, switch good, you have to look at the receiving end. For whatever reason it doesn't recognize (or isn't able) to switch out of 4wd.

Which makes me think of... mechanical issues with the transfer case. Either it CAN'T switch or WON'T switch.

CAN'T could mean grease too thick or nonexistent, or filled with dirt somehow, or something's broken that's preventing it from switching/staying in 2wd even though it gets the signal to do so.

WON'T could mean it's really not getting the signal, or is getting it but isn't able to respond.

I'm not familiar with this truck but some do have manual hubs that coordinate with electronic... if yours does maybe they are "arguing" about who's in charge?

Sorry if this is lame, just trying to help.

 

I'd check the oil in the transfer case to see it isn't to low or dirty.

 

On the drivers side firewall in the engine compartment there are one or more small relay boxes. In one of them you will find two identical relays with nothing else in the box. The box is usually wrapped in fabric electrical tape from the factory. These are the relays that provide power to the shift motor.

Both relays provide a ground path for the shift motor in their normal position. One relay, when activated, provides power to one of the shift motor wires, causing the shift motor to turn in one direction. The other relay, when activated, provides power to the other wire, causing the motor to turn in the opposite direction. Basically, one relay shifts from 2WD to 4WD to 4LO, and the other does the opposite.

Based on your symptoms, I would suspect one of the relays has failed. Try this. Shift into 4x4. Then take the relays out and swap their positions. Both relays are identical so this is not a problem. Once you do this, if I'm right, you should be able to switch back out of 4x4, but now you won't be able to switch in.

If this is the case, inspect the relay bases and the wiring going to the relay box for corrosion. If you find it, clean it up and try again. If no corrosion, replace both relays. They are about $20 each from any Ford dealer. Take one with you though. If you tell them you want 4WD shift relays, they probably won't know what you're talking about. But they can get the part number right off of the relay.

 

Thank you very much dchamberlain. One of the relays were bad. So I replaced it and it works great. It was only $11 at oriellys, and the motor I didn't need was like $150, Oh well guess I have a spare one now . Thank you again for your advice.