2005 Expedition 4x4 Issue - Lights Not Working, 4LO Won't Engage

[mr7743]

I do have an OBDII scanner, but I’m reading no codes

 

[mr7743]

Unplugging the AC controls had no effect. When I had the motor out I tried to use a screw driver to turn the shaft on the shift motor, it was locked up solid. Should I be able to move that manually?

 

[whtbronco]

I doubt all scanners can read the 4WD module, and only high end scanners can control the 4WD module. FORScan can likely read the 4WD module with right adapter.

I'm not sure if you'd be able to turn the shift motor with a screw driver. I never tried. I wish I had kept 1 of the old ones I had so I could take it apart.

I am a big fan of testing to the point of positively identifying a failure before spending money, but in this case it does seem like it's the shift motor.

 

[mr7743]

Thatnks for the heads up. I hate to be a “parts replacer”, but sometimes I go too far in the other direction. New shift motor is on order!

 

[BlackCoffee]

I also do not know if you can turn the motor with a screw driver. It is a step motor that runs the transfer case to the correct gearing. You can remove the motor from the transfer case and see if it turns with the switch. At least that will isolate to a motor problem or an indication problem.

 

[mr7743]

Yes, I did try running it with the switch with no response. Also none of the positional pins on the plug had power, but the other pins did - which does seem to align with a post I found about rebuilding the shift motors online that said one of the main failures was a small bushing that would allow the motor to "lose its place". I assume if the motor had lost its place then the computer wouldn't know which position to apply power to.

 

[mr7743]

Just to follow up, I replaced the motor and everything functions perfectly. Lights on the dash are also functional again. You cannot turn the motors by hand even if they are working for any future diagnosticians

 

[whtbronco]

That's good news. It sure is nice to get things resolved.