Q: "Service 4WD" shows on the dash

asked by on November 04, 2016

Service 4wd is on the dash. The vehicle will switch itself automatically into 4wd no matter what speeds im going. I took the old encoder motor and got a newnone, plugged it in and the service message went away and the 4wd selector buttons on my dashboard worked. I had to change it yo 4wd to line up the pieces to attach the new motor and then the encoder motor stopped working and the 4wd buttons dont turn on and the error message is back. I did replace the 4wd buttons and it made no difference, i checked the ground connections and cleaned them of rust. Nothing works.

My car has 180000 miles.
My car has an automatic transmission.

Hi there. Check the harness wires from the transfer case to the output shaft speed sensor. See if the speed sensor wires are burned and shorted into the harness. This could cause the 4wd to engage when ever and at any speed. The wires could just be touching and not actually connecting until a bump hits them together. If the wiring is all good on the transmission and transfer case, then I suggest having the computer flashed (reprogrammed) to fix the 4wd issue. If you need further assistance troubleshooting your vehicle, then seek out a technician, such as one from YourMechanic, that can assist you with the 4x4 light.

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