I have a 5 speed 4.0L 98 ranger with 4wd. When i bought it the 4wd high and 4wd low lights would occasionally flash while driving and then turn off for a little and come back on. With that, the 4wd wouldn't engage, either low or high. The guy I bought it from said it just needed a transfer case shift motor (he had the old one sitting in the back seat for some reason), so I replaced it. But it's still flashing the 4wd lights in the same way. I got the 4wd to engage properly once but not since. I got a fixd bluetooth code reader to try and read those codes as well as my check engine codes but it seems that it only reads check engine codes. Does anyone have any idea what the issue with the 4wd could be or suggestions on how to read the code?

 

There are no 4x4 codes

1995 to 2000 Rangers used the GEM(generic electronic module) to control the 4x4 system
The GEM is the Body computer, it controls wipers, interior lights, power windows, door locks, and the 4x4 system
GEM is located behind the Radio in the dash


There are 5 parts to the system
1. Dash switch, just 3 resistors, unlikely to ever be a problem
2. GEM
3. Electric shift control, 2 relays in a box next to GEM, it powers the shift motor
4. Shift Motor, on transfer case
5. Dash lights

With key on both 4WD lights should come on and go off, this is a "bulb test" nothing to do with the 4x4 system

If you changed the shift motor you see that it has 8 wires
2 are to power the motor, turn it
1 is for an electric clutch inside transfer case, Brown wire may or may not be on connector
5 are for contacts(sensors) inside the shift motor

Pictures here: https://www.explorerforum.com/forums...-motor.123542/

The Flashing 4WD lights means the 5 wire contacts are not working, or GEM is not

Each position of the transfer case, 2WD, 4high, Neutral and 4low, have a Contact pattern

When you select 4high the GEM sends power to the shift motor via Electric shift control relays
GEM watches the contacts change as motor moves, when 4high contacts are closed then GEM stops sending power to shift motor, and THEN it turns on 4High light on dash

If the dash lights flash that means the contacts are not changing or not in correct pattern

This could be shift motor issue or GEM issue, wiring is also possible but only you would know if wiring looks sketchy

 

If it were my GEM that was failing would the other electronics it controls also be failing? Also is there precedence for getting a shift motor that's bad out of the box? I bought it from the shop as a "remanufactured" product but I'd think the part itself should be fine right?

 

No, they are separate parts and as far as I know one part failing won't hurt/damage another part in this system

"Remanufactured" part would probably be more likely to work than a "new" part now-a-days, Quality control has shifted to the User/Buyer of the new part, it too expensive to test every part that leaves a factory, labor cost is just too high.
Car makers pay extra for the parts to be tested, which is why a Motorcraft(ford) or AC/Delco(GM) part cost ALOT more than 3rd party parts

Remanufactured part should be tested before shipping but can't say for sure, 3rd party new is NOT tested, for sure, lol.

First test I would do would be to unplug the shift motor and test if the 2 wires from the cab that sends 12v and Ground are indeed sending voltage and ground to the motor
They would be the solid Yellow and solid Orange wires on the 8 wire connector
If there is no 12v and ground when shifting is activated then problem is in the cab not shift motor
Could be GEM or Electric shift control(dual relay box)

I am assuming you have checked the 3 fuses for the 4x4 system
Fuse #3 in engine fuse box
Fuses #20 and #25 in CAB fuse box

 

Yes, fuses are fine. I just took another look under the truck and I just noticed a single wire hanging from the transfer case that looks like it had simply been cut. I'd assume this is the ground, but I don't see any wires that look like they're supposed to be spliced to the cut one on the t-case. Am I wrong to think that is the ground and that's why the shift motor isn't getting power?

 

No probably not a ground

If its a Brown wire then its for the electric clutch in the transfer case, it was wired direct to the connector on transfer case so had to be cut when working on shift motor, many never hooked it back up.

It won't prevent 4WD from working, it was only used for "shift on the fly" and that still worked even without the electric clutch

Shift motor has an Orange and Yellow wire for 12volt and ground, and they reverse polarity so motor can spin both ways, like power window motor, up and down

 

This may or may not be related but I am also having some issues with my dome light and door switches. Every time I turn off the truck and get out the dome light stays on. However, when I start the truck and and drive for a few seconds, the light turns off. Also, the door ajar light is pretty frequently on while both doors are shut. Additionally, when I turn the truck off, it occasionally dings as if I have the keys in the ignition and the door open though the door is shut and the keys are in my hand. This all sounds like the GEM to me, though its not 100% of the symptoms I've read about.

 

Reads more like a bad/failing door switch to me

 

I have a 98 B3000 and just went through the same problem you have. I tried several things to fix. In hindsight here’s how I’d handle. I may not use the proper terms for some of the parts. I am assuming you cleaned the plugs on transfer case motor with contact cleaner when installing.
1) check all the vacuum hoses. From the motor to the solenoid to the hubs. If still not working,
2) take out radio and check plug on selector switch. Clean with contact cleaner. While radio is out, take out GEM and clean all plugs with contact cleaner. While GEM is out, take out the 4wd module that’s in front of the GEM. Again clean all plugs with contact cleaner. Now put all back together. If not working,
3)replace the 4wd module. I found one at a junk yard. Couldn’t find a new one. Used ones are out there. Make sure to clean the contacts on new module before replacing old one. If that doesn’t work
4) replace the solenoid. Can get new from parts store. If this doesn’t work.
5) you are on your own. I did all this, not in this order though, and fixed mine. Could be GEM going bad. Triple check all fuses and clean them also.

 

I have been looking for this info for a long time now. Thank you.

I do have a question. I went to a local shop and they told me it was the shift motor. They wanted hella money so I went to autozone and replaced the shift motor but the 4HI and 4LO lights still flash 6 times every 2 minutes and the 4x4 will not engage. I checked the Dash switch and its fine, as well as all the fuses. I am assuming that the new motor works... I removed the motor from the transfer case and then switch to 4HI while looking at the key that turns the transfer case and it did not move, meaning either the new motor is faulty or its not getting any power. Are there any ways to check the GEM, being the only thing left?

 

I’m no where close to being as smart as most others here. But what I do know is that the GEM will not tell the motor to turn if all the other steps are not done. Completing the circuit might say.
I was in same boat as you. Got same info as you. Change the motor. Well I did and still had no 4wd. Did all the other steps and fixed. What I did was try to list easiest/cheapest steps first to see if fixes then spend most on the new transfer case motor. So if you’ve cleaned all the connections, changed module in front of GEM, changed solenoid, and positive no vacuum leaks, new motor actually works, then possibly is the GEM.

 

Welcome to the forum juan

What YEAR Ranger?

There were 3 different 4x4 systems used from 1983 to 2011 Rangers
1983-1994
1995-2000
2001-2011

Each is different that the other years

Always check the fuse in the engine bay, it powers the shift motor, flashing 4x4 lights means shift motor is not turning when controller tries to activate it

 

Listen to him, he’s the smart one!!!

 

Thanks! I have been getting awesome info from this forum ever since I bought the Ranger 3 years ago! I am honored to learn from you guys! This ranger is going to be my project car which I am very excited about.

I have an automatic 4.0L 2000 Ranger with the 4wd.
I have checked the fuse in the engine bay and it looks fine.

 

Then my GUESS, from your description of the problem, in a 2000 Ranger, would be the Dual relay box behind the radio is unplugged or has failed

The GEM module, also behind the radio, is the 4WD Controller, the"brains", it also runs the other cab electrics not just 4x4 system
The switch on the dash is just 3 resistors, GEM sends it 5volts when key is on, GEM gets back 4volts if switch is in 2WD position, 3v is 4high, 2v is 4low, so pretty simple

The dual relay box, behind the GEM, is connected to the GEM and to the shift motor's 2 power wires, it is powered by the fuse in the engine fuse box
Each relay is a Ground when OFF, each relay controls one of the shift motors 2 wires

When you change the switch position the GEM "looks" at current position so it knows which way to turn the shift motor, clockwise or counter-clockwise
If you were in 4high and selected 2WD the GEM needs to turn shift motor clockwise
If you were in 2WD and selected 4high then GEM needs to turn shift motor counter clockwise

Then GEM then activates ONE relay in the dual relay box(you should HEAR this relay "CLICK" in the area behind the radio), making that wire 12volts, the other wire is already a Ground, so shift motor has 12v/gnd and starts to move
On the shift motor housing are 5 Position wires, these tell the GEM what position the transfer cases Shift Rod is in
The GEM powers the relay until shift rod is in the correct position, THEN it will turn on the 4high light, or turn it off if 2WD
If the Lights flash that means the shift motor did not move when power was sent to it

So flashing light means switch is working, or GEM wouldn't try to move shift motor
Flashing lights also mean GEM is working since it is flashing the lights

Which brings you to the shift motor not working
You could test if the shift motor was getting power when switch is changed
And it could be a wiring problem

Since you changed the shift motor and still had the same symptom, then wiring issue is still on the table, you may want to check if motor is getting 12volts when switch is changed
And do you HEAR THE CLICK?

 

Awesome explanation on how it works. I really appreciate you taking the time to explain that to me.

I do not hear this relay click when turning the switch. I will remove the shift motor and check the voltage on the pins that correspond to the power wires going to the shift motor but from your explanation, it sounds like the relay is not getting the power or is faulty. If I disconnect the relay I should be able to test the power going to it correct? If it is getting power than I can assume its the relay gone bad?

Thanks again Ron. I really appreciate your help.

 

Yes, here is the wiring diagram for 4WD in a 2000 Ranger

The dark green/light green stripe wire comes from the 20amp fuse in the engine bay fuse box, and feeds the 12volts to those two relays, which powers the Yellow or Orange motor wires
It doesn't show the dual ground but as far as I know that's its only goof

The dual relay box is called the electric shift control
If you do hear it clicking then I would GUESS its working, and either it has no 12volts to send to the motor or GEM doesn't have a good connection to the 5 Contacts so doesn't "know" where shift rod is at, so shuts off the relay instantly and flashes the lights

Good look here at the shift motor and housing: https://www.explorerforum.com/forums...-motor.123542/

 

Sorry I am just now answering. Life got really busy and didn’t have time to mess with the truck.

Update:
I got a relay from eBay and installed it. Still doesn’t work. I gave the shift motor 12 volts to make sure it works and it does. I checked the pins to make sure that there where 12 volts and whenever the switch was moved it had zero volts. I also realized that the shift motor wires and the trucks pins are not the same. The truck has 8 wires and the motor has 7 wires. I also believe that the power wires are in different location.

I have a bit of time next week so I am going to try to work on it as much as I can and hopefully figure out what’s wrong with it.

On truck

On truck

On shift motor

On shift motor


Ron that wire diagram has come in handy so thank you.

 

Has this 4x4 system ever worked?

Just asking because it wouldn't be a connector issue if it did work before

 

Yes it worked when I first bought the truck. Once it stopped working I took it to that shop. They told me it was the shift motor. My big mistake was that I did not compare the wires of the new motor to the old. Once I installed the motor it worked the first time then it never worked again.

 

Ron,
I was looking at the diagram more carefully and the one you posted is for the 4wd with the pulse vacuums hubs. My truck has the live axle, no vacuum hubs. Do you happen to have the wiring diagram for that version of the 4wd?

 

Well that's the only one for 2000

The 2001 Ranger used Live axle, no hubs, and a totally different electrical system for 4WD
Some 1999/2000 Rangers did get Live axle because of PVH issues

1998 to 2000 used GEM module for 4WD control
Live axle and 2001 and up used a separate 4x4CM(control module) found behind the passenger side kick panel

diagram below

 

Okay, well I definitely have the wiring of the 2000 ford ranger. The GEM and dual relay are behind the radio but I have a Live axle. I do see that the 2001 one has 7 wires on the transfer case instead of 8 like the 2000. That means I bought the wrong shift motor? Could that be the whole problem? But why wouldn’t I be getting power in the connector?

I just checked the yellow and orange wire in the “new” dual relay behind the radio and once the switch is moved from 2wd to 4HI and zero voltage. All the other wires had ~14 Volts. (Except yellow, orange and Black (ground)) I checked the fuses and all are good. I also checked the voltage of the switch. It was getting ~ 3.8 volts in 2wd, ~ 2.8 V in 4Hi and ~1.8 in 4LO. I think it’s close enough to the 4, 3, and 2 Volts respectively to assume the switch is good.

Should all the wires going to the dual relay have ~14 Volts? I thought the dark green with light green wire was the supply power for the dual relay?

I wrote the voltage for the wires on the diagram I attached.

 

Yes, with key on, or in this case engine running, they should all be about 14volts

The yellow and orange wires are both GROUNDS(0v) until GEM activates one of the relays
GEM grounds a relay to close it, so until relay is grounded it will show 14v on both wires

When 4x4 selector switch is moved the GEM should ground ONE relay and either the Yellow or Orange then have 14v, the other wire(yellow or orange) is already a ground so motor moves

 

Okay so I checked both relays and they did not close. Is there a way to check if the GEM is sending the signal the to close one of the relays? I guess its possible that the dual relay I bought is bad, but does this mean that GEM is bad? Thank you again for all your time and help. I really appreciate it.