Hello recently the 4wd stopped working in my friends 2002 Ford Ranger 4.0 Automatic.. There is a switch on the dash close to the radio that you can turn to put it in 2wd... 4x4 HI... 4x4 LOw.... Now when you turn it there is no light that appears in the console.. IT Does come on when you first start the truck the 4wd light does.... but now when you turn the switch for either HI or Low it will no longer come on to where you can see it is working...... And I know 4x4 is not working as well cause of how it spins coming up driveway...

I checked all fuses and they are fine..
I cannot find no where that there is a Relay for 4x4

There is a clicking sound that comes on at the floor of the passenger side it is the 4x4 module... it will click on and off for a while.. Not sure if it is suppose to do that are not?

if anyone could give me some advise on all this it would be really appreciated... Parts are not cheap no longer if they ever were... So i sure hope not to have to guess and buy different things only for it not to be the problem for my friend... Thanks

 

There are 6 fuses involved with 4WD system

1 in the engine fuse box, #13, 20amp <<powers the motor on transfer case
And 5 in the cab fuse box, #5, 9, 10, 11 and 28

You have a Shift Control Module in a 2002 Ranger for the 4WD, thats what you hear clicking, it has relays inside that send power to the shift motor

These are known to fail, but I would check shift motor first.

The basic shift motor has not changed since the first Ranger 4WD
Good read here with pictures: How to: Rebuild 4X4 Shift Motor | Ford Explorer and Ford Ranger Forums - Serious Explorations

In the first picture you can see the larger Orange and Yellow wires running to the motor
Remove motor and apply 12volts(battery) and Ground to those wires, then reverse 12v and ground to turn motor the other way
If motor is working replace Shift Module(wrecking yard)
If motor is not working replace it(wrecking yard)

Once you get system working again, make sure your friend shifts it into 4high and then 4low and then back to 2WD once a month, don't have to move the truck, just shift it thru all 3 settings, this keeps the motors brushes clean, the 6 months between use is what causes the most problems

Here is wiring diagram

 

Ok thank you , once i get back monday from a small vacation I will get with him and check those things out and then let you know... Thank you again

 

Hi I checked it out as best as I could , all the fuses I checked out and they are all ok... I had my friend to turn the switch back and forth as I layed under his truck to listen for any sound coming form the shift motor, at first I could not hear anything, then I banged on the motor with a rubber mallet and then I could hear it click back and forth as he turned the switch from 2wd to 4wd high...

My question is then if it worked even for a few, why didn't the 4wd light come on the dash that shows it was not engaging into 4wd?

He wants me to order him a shift motor though just in case that is it... I just do not want him to spend money on things when it might not be the problem...

The 4wd lights up when you first start the truck then goes off which is of course normal.. but now when the truck is started and you switch the switch from 2wd to 4wd high or 4wd low there is no light that appears on the dash.

Thank you

 

2002 has 4x4 shift module in the cab

Shift module turns on the 4WD light AFTER motor turns to correct position.
Inside the motor there is a Contact Wheel and 5 contacts, this is how the shift module "knows" where transfer case shift rod is, 2WD, 4high or 4low, each has a different contact matrix, as seen in the link I posted above.

First, tapping on the motor and having it start to work again means the brushes for the motor part are going bad, so motor needs to be rebuilt or replaced, period.
It also means the 4x4 shift control module and fuses are OK, well 95%

If the motors brushes are corroded then the contacts may be as well, so shift module won't turn on the light because it is not sure of the position.

You have the wiring diagram so you can see that fuse 11 powers the 4WD lights(thru main light switch) when key is on.
The 4x4 shift module GROUNDS the 4WD lights to turn them on, that ground comes from the contact wheel in the shift motor


Just a general heads up on automotive wiring and control modules/computers.
Almost every thing is now controlled by GROUNDING
Running 12volt wires every where is foolish when a ground is safer and does the same job.

i.e. fuel injectors have 1 12volt wire that daisy chains from one injector to the next, all get 12volts when key is on, but have no GROUND, there is 1 ground wire running back to computer from each injector, computer Grounds the injector to open it
Fuel pump relay is grounded by computer to turn it on.
Almost all relays are controlled by grounding

 

UPDATE I put in a new shift motor that I got off ebay, that was the same part number as the one that advance auto parts sales. It was a little cheaper so bought it from ebay, but I am afraid it did not help at all.

Here is what I noticed though that might be helpful information. After it would still not go into 4wd hi or low... and the dash light never came on.

I plugged the old motor back up to the connector just to see what happen, So I had the owner of the truck who is a friend of mine, set inside the truck with key on to turn the switch from 2wd to 4wd hi and low... Here is what I noticed where the piece that slides into the rod on the tranxaxle housing.. In watching it , when taken from 2wd to 4wd hi, that piece will turn but will not stay where it is turned it goes back to where it was

If you go from 4wd hi back to 2wd it turns for a second then goes back again to where it was ... no matter where that piece that fits into the rod on the transaxle turns it will go back on its on to where it started from.

So a couple questions please... should it not remain in place where ever it turns to keep the rod turned such as 4wd hi should it not remain there until you put it into 2wd?

cause seems to me if it goes back like that off the transaxle, if then on the transaxle bolted to it, then it would turn the rod to 4wd hi then by itself turn it back on its on.

I hope what I am saying is making since, trying to explain it the best I can..

I do not no much about 4 wheel drives.. but if you turn it to 4wd hi is that module on the passenger side suppose to only click once to engage the motor in that direction?

cause his module will click on and off for I would say 1 to 2 minutes before it stops making noise.

All i can think of now to try is a Module, cause all the fuses I am 100 percent sure of is fine.... and it now has a new shift motor on it.... that should as far as I know be all that is left to try?

It is not controlled by a vacuum line is it?
Thank you for your help.

 

That would be normal if motor was working but Shift Module was not getting the signal from the motor about its current position.

Safety feature in that the transfer case will stay in its current position if Shift module doesn't "know" where it is

Shift module gets the "signal" when dash 4WD switch is used
Shift module powers up the shift motor
Motor turns but there is no changing of Contacts IN the motor
Shift module STOPS moving the motor to avoid damage
Shift module returns motor to previous point, so it doesn't strand driver in Neutral or an in between setting that could damage transfer case

You are down to wiring or shift module

 

I ordered him a Shift module from ebay, best he could afford at this time, so hopefully it will be a good one since it is used.

Then after that will have to check more into wiring, I have not seen nothing wrong with wiring so far in checking them out but who knows... I told him though that I do not know much about how 4wd works, I work on a lot of cars for people to help them out, but certain things when it comes to 4wd I just do not know much about.

And guessing is costly but told him we had to try something.... Thanks

 

Shift module is not an uncommon issue on 2001 and up Rangers.

See lots of posts about them failing

2001 and up 4WD Rangers just have transfer case shifter, so no auto hubs or other 4WD stuff

Problem is 4WD is not used that often in 90% of these so sitting unused makes them fail
Shift once a month, to keep it working

You can also change it to a Shiftster, $60
Here: https://the-shiftster.myshopify.com/.../the-shiftster

Remove shift motor and replace it with the Shiftster, manual shift for transfer case, no doubts, you will ALWAYS have 4WD
Down side is you do need to get under the truck to shift it

 

Thanks I will let you no how it goes once his module comes though the mail and I put it on.

 

Hello... I guess I am going to have to throw in the towel... I have wore my neck and arm's out under his truck messing with the shift motor after putting on the used shift module that came today in mail. It did not help in putting a shift module on it.... All i can see is if you take the shift motor off the truck and turn the rod on the transaxle by pliers and point it to 4wd HI... and then test it ... it will work fine, tires do not spin at all testing it ... but of course the dash light does not show it is in 4wd hi cause the motor is not hooked up to the rod

All i can think of is the motor just is not turning the rod to point at 4wd hi even though you can hear it each and every time when my friend turns the switch from 2wd to 4wd hi...

but I just do not have a clue how to fix it for him....

 

That would be normal if motor was working but Shift Module was not getting the signal from the motor about its current position.

Safety feature in that the transfer case will stay in its current position if Shift module doesn't "know" where it is

Shift module gets the "signal" when dash 4WD switch is used
Shift module powers up the shift motor
Motor turns but there is no changing of Contacts IN the motor
Shift module STOPS moving the motor to avoid damage
Shift module returns motor to previous point, so it doesn't strand driver in Neutral or an in between setting that could damage transfer case

You are down to wiring or shift module




It looks like my friend is going to bring his truck by the house again today for me to look at... :(....

Let me try to understand this .. so the switch sends the signal to the module... the module if all is working correctly should just click once if switch is put lets say into 4wd Hi... then the shift motor turns the level in the trans to point to 4wd hi and stay there?

if working correctly the shift motor will not turn it in the direct of 4wd hi but then return it into the place it started?

If what I am thinking is correct what would be the problem that keeps the module not letting it go into 4wd hi and causing the dash light to come on?

cause it has a new motor on it unless I did not put it on correctly, cause i seen a video of where a man just put it back on a new one.. with mine i have to put it on then lift up on the motor to line it up with the bolt holes to attach it to trans... that then puts a bit of pressure on the motor instead of no pressure at all ..


Anyways going to look at it again, Just aggravating after him buying a new motor even though from ebay still a new one... bought a used module, and sure a used one always makes me wonder if it was good are not, but it clicks off and on like the old one did that was on it, so not sure of that..

thats my update so far...lol

 

The 4WD switch is just 3 resistor
4WD module sends the switch a constant(key on) 12 volts(for example), could be 5volts, doesn't matter really as long as it is "known" but 4WD module.
Voltage passes thru a resistor and comes back to module reduced in voltage, say 10v is 2WD, 8 v 4high, and 6volt 4low, again doesn't matter as long as there is a change in voltage the 4WD module understands.
(Cruise Control uses same setup, 2 wires and resistors handle ALL the settings and controls on the steering wheel)

So 4WD module gets voltage from 4WD switch

Shift motor works like Power window motor, 12v/ground rolls window UP, ground/12v rolls window down.
So 4WD module controls 2 relays that control polarity to shift motor, to turn it clockwise or counter clockwise.

4WD module "knows" what position the transfer case is in by the contact wheel inside the shift motor.

So it "knows" which direction to turn the motor to change transfer case from 2WD to 4high, or back to 2WD from 4high, by seeing what contacts are open and closed on the contact wheel

If the 4WD module applies voltage to the motor and contacts do NOT change then it STOPS and returns motor to previous position
4WD lights should start flashing at this point, letting driver know there is a problem.

With shift motor off transfer case and hooked up to wiring you should be able to change 4WD switch to all 2 positions and shift motor should rotate to all 3 positions

If not then there is something wrong in the control system or motor.

If motor does work and moves to all positions then there is something wrong in transfer case

There is no sensors inside transfer case for position, that's only done by shift motors contact wheel

 

Hello Ron, First I would like to Thank you, you gave me your time and effort to help me not many would do that these days... So I really Thank you a lot.

My Friend just left and his truck is now working in 4wd... This also might help others in posting the results:

It must of been the shift module under the cover on the passengers side... when I first hooked it up it was clicking off and on for like 4 times, when i would put it in 4wd hi it would click at least four times... then when i put the switch in 2wd it would click at least four times then also.

So he pulled into my drive way, and I had read that sometimes the module has to set sometimes up to 24 hrs to reprogram itself, rather that is true are not I am not sure, but anyways when I got into his truck to move it to where I work on things... I put the switch into 4wd hi just to see if maybe what I had read might be true.

and the 4wd light came right on.. and the module only clicked once ... then i went back to 2wd and it clicked once and was now back in 2wd.

so it must have to just click once for it to work...

Also i had read to put into 4wd low you have to put the truck in neutral... I tried it in park and it would not work... so put it in neutral then the 4wd low came on the dash and the module clicked once and then was now in 4wd low.

So since I have not did nothing else since yesterday, it must have to reprogram itself after installing a new or used one before it will work again.

Thank you... all I know is it is working again, and wow am I ever glad...lol

 

Good work

Yes, single "click"(relay closing) to start the motor and then wait for contact wheel to get into desired position would be "normal", but then a "softer click" may be heard as relay opens.

The multiple clicks could indicate no return signal from contact wheel or no movement of motor(no contact changes)

Never heard of the "wait and see" issue with replacement module, could be, just never ran into that myself

Tell him to shift it once a month to keep it working

 

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