4x4 issues

[paw7889]

Hello everyone and thank you for looking. My 03 explorer 4.0 has no 4wheel drive and am out of ideas for where to look. When i bought it it had a flashing 4x4 high light (10 times per cycle) and an ABS light. My cheap scanner said the problem was the rear abs sensor so i replaced it and the abs light went away but not the flashing 4x4 high light. My 4x4 still didnt work so i went to the junk yard and found a 4x4 control modual and replaced that but still no luck. Lastly I took the transfer case motor down and opened that up but it looked fine. I have not found any blown fuses or broken wires any ideas would be appreciated. Thank you Phill

 

[joecrna]

B&W 4405 transfer case. Give the rebuild diary in the transfer case forum a read to get a better idea how this case works. Scanning takes an expensive NGS scanner and someone experienced in using it to be of any use. The shift motor only engages low range. 4wheel drive is activated via an electromechanical clutch that uses a ball ramp design. The famous brown wire carries the signal to activate the clutch's selonoid.

Do you have an electronic signal on the brown wire at the transfer case? This will determine internal vs external issues.

 

[paw7889]

It appears to have 4 volts on the brown wire. I tried a couple different ground areas but that is as high as i read. I did see a black wire that doesnt go anywhere but it apears to be crimped and covered deliberatly and is on the motor side of the harness.

 

[joecrna]

Sorry about slow reply. That is correct, I believe the max brown wire is rated at 5 volts, so yours is fine. Have not figured out exactly what the black wire you referenced is, no matter. You have just eliminated 95% of external issues such as that control module. Now you are left with many internal problems.

Most often not a mechanical one such as a failed electromagnet or ball ramp, though those are possible. More frequently, the failure is a Hall effect sensor, output shaft speed sensor, transmission position sensor or the like. Tracking these down is largely a matter of guess work or using an NGS scanner.

Around here, that means going to one of two Ford dealers (now just one has a tech that can actually make good use of it) and paying for diagnostics. Sorry but that has been my experience.