4wd Electric Shift Issue

[Jody]

I have gone through the steps on this tech article http://www.therangerstation.com/tech_library/4wd_control_module.html and still cannot get this to function.

1994 Ranger super cab, I have replaced the module and the new one tests as working. I have three different motors that I have verified all functioning. Fuses are good. The switch panel tests good also. When I plug everything in nothing happens. Sometimes when I start the truck the indicator will show 4hi or 4lo engaged but I know it is not. I have no issue with the transfer case or the hubs as I can manually shift it into 4hi or 4lo and it works fine. I just cannot get the electric shift to work.

Any ideas on what I should look for or test next?

 

[RonD]

There are electrical diagrams for Shift Control here:
http://www.therangerstation.com/tech_library/EDiagrams/index.htm

Could be something as simple as a disconnected Ground wire.
It is often easier to use the chassis ground when testing for correct voltage, so the focus is on the 12volts, but there is no 12volts at a device if the device's ground isn't there.
So test the ground wire or use the device's metal case when testing voltages, that 12volts can drop to under 5volts with a marginal ground

 

[Jody]

I'll check the grounds and start checking each wire. Not much else to this system than the wiring harness.

 

[FritzTKatt]

Test the harness continuity. Set the meter to ohms and check it from pigtail to pigtail. This will probably require a buddy and a long jumper wire. If the needle spikes you have a fault.