Good Day All
As it it now October, I thought I would make sure the 4x4 works before I need it.
It took a while to get it the 4H lamp to illuminate. Could not really tell if it engaged or not there was no servo noise. When I attempted 4L there was this awful grinding noise, the speedometer jumped to 40 mph (the truck was idling in neutral) and the seat belt light was illuminated.
Any one have thoughts as to what went south? My first though is that the sevo motor needs either to be lubed or replaced, but with the speedometer acting up I am not sure if I have some computer issue or a combination of factors.
The truck has 65K and only sees 4x4 duty in the winter (and that is only occasionally).
All thoughts welcomed.
Thanks for your time.
Omni

 

The speedometer is changed when in 4Low, but should stay at 0 MPH if you are not moving, thats a PCM issue
The grinding means transmission was STILL spinning so somethings not right there, and that would explain the 40MPH jump, speed comes from transmissions output shaft
Are you SURE you were in NEUTRAL and not D, so column shifter is OFF, assuming automatic

But the PCM is not part of the 4WD system, it just gets a signal that 4Low was selected
4WD is run by the 4x4CM(control module) behind the radio in 2004 and up Rangers
System just has 3 parts
Dash switch, never breaks
4x4CM, can have problems
Shift motor on transfer case, usually dies from not being used, electric motor brushes get corroded or stuck

You should always shift from 2WD to 4H then 4L then back to 2WD once a month just sitting in the driveway to keep the shift motor in good working order

You can pull the shift motor off transfer case and connect it back up to harness then run it thru it selections, 4H, 4L and 2WD a few times to try and get it cleaned up inside
It doesn't need to be grounded to transfer case to work, just FYI