Way to test 4x4 Electrical System?
 

I've gained a bunch of useful information off of this forum, thanks!

I bought a used 1999 Ranger 4x4 4.0L and the previous owner was not honest about all of its problems. I'm trying to get the 4x4 working and was told the only problem was the front driveshaft wasn't attached. I replaced the ujoint and CV joint and mounted the driveshaft.

Did not help as the 4x4 lo and hi lights flash together and it doesn't engage the front driveshaft and nothing happens when I turn the knob to 4x4.

Is there any way to test the electrical control of the 4x4 system down to the transfer case shift motor? I want to make sure it is getting the right signal and something else isn't wrong before I replace it.

I think I've checked all the related fuses. But want to make sure it isn't one of the relays or control modules or heck, even the dash switch which I made sure was connected securely.

Thanks!

There are a couple of fuses on the 1995 and up 4x4 system, I believe there is a 20amp fuse in the engine fuse box that can blow, this powers the module but not the dash lights, so dash lights flash to indicate a problem.

Just FYI the flashing 4x4 lights are not specific to any specific problem.
Yes, shift motor is a common problem on the rangers, it is usually from disuse, if the shift motor is not used much the contacts inside get corroded, and when you try to shift the motor doesn't move.
So once you get it working, shift to Hi and Lo once a month.

Shift motor rebuild here:
Servicing A Transfer Case Shift Motor

Thanks for the reply, is there any way to test if the shift motor is getting the proper signal with a multimeter?

The shift motor gets 12volts, like power window motors, on it's 2 wires when activated.
The other wires on the motor housing are "sensor" wires, they "tell" the 4x4 module the position of the transfer case shifter.
These are just contact wires, as the shifter rotates it makes and breaks connections in those wires for the 3 positions of the transfer case, 2H, 4H, 4L

Test the connector for 12 volts.
Use a standard Multimeter set for DC Voltage and start checking.

If no voltage then you need to go further.

The earlier motors have problems, often crashed.

12v should be passing through