Four-wheel drive not working, keeps blowing fuse

Let's start with finding out which fuse is blowing. This is not going to matter much in how to test this circuit, but we should be on the same page.

Basically, the way we need to find out if the wiring is the issue is to disconnect the connector with this wire in it and check the wire for a short to ground. Basically, when the connector is off the path to ground is removed.

So, if you have continuity to ground then there is a short in the wiring and it needs to be replaced.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

See the wiring diagrams below and let me know what questions you have.

Thanks

I finally found time to work on the wiring. Upon further investigation I noticed that one of the connectors that is used to connect to the 4x4 control module was changed out with another used connector, by the previous owner. I also noticed that the one (grey) connector only has 12 wires to it and the one that was changed out has only 13 wires. Does Ford use a standard wiring color code?

That is interesting. The standard color of the wiring is what is shown in the wiring diagram.

Can you get a picture of this connector? What I would suggest is we ohm out the wiring and find out if there are any that are shorted together. You do this by disconnecting the circuits at both ends and then check resistance (ohms) between all the circuits.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Let me know what questions you have.

This grey connector is the original on the vehicle.

The black connector was added to the circuit.

I’m not sure what year and model the black connector came from. Because some wires were not hooked up, the wires in the photo that were not taped.

Okay. I am not sure I understand how the black one was connected. Was it in the place of the gray connector? So, the gray one was just hanging there?

If that is the case, more than likely someone wired in something else like an alarm or remote start.

What was this gray connector going to?

The original issue of the fuse blowing is going to be caused by a short to ground on that circuit. So, can you also tell us what fuse is blowing?

No, there are two connectors attached to the control module behind the glove compartment. The grey connector is original the black connector was added to the second set of wiring.

Okay. Which fuse is it that keeps blowing? That will help us figure out if this could be the issue because it is going to be something on that circuit.

Fuse # 18 keeps blowing.

Okay. That helps. So, what we need to do is unplug the things that the control module feeds.

So, if one of these are shorted then that will cause the fuse to blow as well.

When you unplug the control module then you are eliminating the short as well but if that was replaced then clearly it wasn't the module.

I would start with the transmission range sensor and then the transfer case shift motor.

I attached the diagram below again with these circuits highlighted.

If this still causes the fuse to blow when they are unplugged, then we need to start checking for each circuit and a short to ground.

To do that, we remove the control module connector and check the resistance for each circuit to ground. They should all be open circuits or OL on the meter except for the ground circuit.

So, you use your red meter lead on the terminals of the connector and the black on a known good ground like a bolt on the frame rail.