4WD not working, please help me to get this fixed

[1930]

98 Ranger, 4.0 trucks in great shape, not abused but poorly maintained and so Im having to fix things that shouldnt be broken. I doubt anyone has ever used the 4WD but I need it.

Here what I know, Im hoping someone can tell me where to start without throwing parts on it.

Ok here goes, hopefully I dont miss anything

1- bought truck a few weeks ago, guy said 4WD worked fine, took it for a drive and noticed the 2WD and the 4WD light flashing simultaneously on and off.

Moved the knob on the dash, nothing lit up as far as an indicator that I had shifted out of 2WD/

The truck did not go into 4WD.

2- Driving the truck, not liking the fuel mileage, tired of seeing the flash I decided to put a jack under the front and rear axle, get it off the ground and see what was spinning.

3- Did this, only one in the right rear was spinning so I knew I was in 2WD.

Put the vehicle in park again ( still up in the air ) and moved knob to 4high and 4 low. Put it in drive and nothing spinning but the right rear.

4- Put it back down on the ground, put the knob back in 2WD and parked truck in my driveway.

5- Got up this A.M started truck and light on dash said 4low and also OD OFF was flashing. I drove the truck a short distance and indeed it was in 4 Low.

6- Even though I have no Fn clue what Im doing I removed the shift motor and turned the pawl in there until
it finally was in 2WD. I did not put the motor back in place but instead zip tied it to the shield under transfer case where it is still now.

7- Drove the truck a great distance today and all it did was again flash the 4high and 4 low light but at one point it stopped doing that, now its flashing that its in 4 low and the O/D off is again flashing. ( its not in 4 low though )

PLEASE tell me how to fix this, where to start. Thank-you

 

[Uncle Gump]

The first place I would go is here...

https://www.therangerstation.com/how-to/transmission-transfer-case-driveshaft/

All kinds of information that will probably get you to where you want to be

 

[Dirtman]

When the OD off light flashes it means there is a DTC for the transmission. Take the truck to autozone or whatever and get the codes read. The transfer case does not have DTC's but the lights flash when the shift motor is told one thing (go in 4-hi) and the sensors detect it is in another thing ( 2wd or 4 low ).

First thing to check is simply the fuse for the 4x4 shift motor then test the switches and sensors.

 

[RonD]

In 1998 the Body Computer(GEM) controls the 4WD system
The 4x4 module is just 2 relays in a box

Since you took off the shift motor you have seen the 7 wires connected to this motor
(there are 8 wires, the 8th wire is for the electric clutch in the transfer case, which is part of the "on the fly 4WD shifting" but can't effect whether or not it shifts)

Only 2 of the 7 wires are for the electric shift motor, it works like a power window motor
12v/Ground, turns it clockwise(window up)
Ground/12v turns it counter clockwise(window down)
So reversing polarity on the 2 wires gets it to turn the direction you want it to go

And thats what the 4x4 Module is for in 1998, the two relays, each relay is for one motor wire and each relay Grounds its one motor wire when off.
To move the motor the GEM activates one relay, which sends 12volts on that one motor wire(the other is already a Ground), and motor turns clockwise, or counter clockwise, depending on which relay was activated.
Easy peasy for this part.

The OTHER 5 wires are for sensors(contacts) inside the shift motor housing
If they are aligned correctly then certain contacts are open and the rest closed when in 2WD position, then they change as motor turns until contacts are in 4high position, and then the same for 4low position, so there are 3 different open and closed contact settings that the GEM "knows".

Contact wheel seen here along with other info: https://www.therangerstation.com/how-to/transmission-transfer-case-driveshaft/rebuilding-a-ford-transfer-case-shift-motor/

This contact wheel is how the GEM knows its starting position, say 2wd, when you select 4high....
GEM activates one relay to move motor counter clockwise, GEM will see the contacts opening and closing as motor turns, then it deactivates the relay, stopping motor, when 4high contact pattern is seen, and THEN it turns on the 4high dash light, so there should ALWAYS be a delay from when you select one of the 3 positions until dash light comes on.
If dash lights flash that means GEM is confused or motor is not moving when it closed the relay.

The 4WD knob or buttons on the dash are just 3 resistors, GEM sends this switch a steady voltage, the return voltage, thru ONE resistor, tells it what the current selection is, when switch setting is changed GEM voltage changes, and it will then move shift motor to that selected position.

You can operate the shift motor while it is off the transfer case to test if its working, it doesn't need to be Grounded to the vehicle

An just FYI the transfer case shift rod may not stay in 2WD with no shift motor in place there is nothing holding it there


1998 GEM and 4WD wiring diagrams here: https://therangerstation.com/forums/showthread.php?t=162915
Check fuses first




In 1998, Rangers got PVH front hubs, Pulse Vacuum operated locking Hubs
These were a bad idea and Ford dropped them completely by 2001
But if your front driveshaft wasn't turning in 4WD then Hubs are not the first problem to address

Troubleshooting PVH here: https://therangerstation.com/tech_library/troubleshoot-fix_pvh_hubs.shtml

Locking PVH here: https://therangerstation.com/Magazine/Apr04/offroad.htm

Swapping PVH out here: https://therangerstation.com/tech_library/AVM_hub_swap.shtml

 

[1930]

In 1998 the Body Computer(GEM) controls the 4WD system
The 4x4 module is just 2 relays in a box

Since you took off the shift motor you have seen the 7 wires connected to this motor
(there are 8 wires, the 8th wire is for the electric clutch in the transfer case, which is part of the "on the fly 4WD shifting" but can't effect whether or not it shifts)

Only 2 of the 7 wires are for the electric shift motor, it works like a power window motor
12v/Ground, turns it clockwise(window up)
Ground/12v turns it counter clockwise(window down)
So reversing polarity on the 2 wires gets it to turn the direction you want it to go

And thats what the 4x4 Module is for in 1998, the two relays, each relay is for one motor wire and each relay Grounds its one motor wire when off.
To move the motor the GEM activates one relay, which sends 12volts on that one motor wire(the other is already a Ground), and motor turns clockwise, or counter clockwise, depending on which relay was activated.
Easy peasy for this part.

The OTHER 5 wires are for sensors(contacts) inside the shift motor housing
If they are aligned correctly then certain contacts are open and the rest closed when in 2WD position, then they change as motor turns until contacts are in 4high position, and then the same for 4low position, so there are 3 different open and closed contact settings that the GEM "knows".

Contact wheel seen here along with other info: https://www.therangerstation.com/how-to/transmission-transfer-case-driveshaft/rebuilding-a-ford-transfer-case-shift-motor/

This contact wheel is how the GEM knows its starting position, say 2wd, when you select 4high....
GEM activates one relay to move motor counter clockwise, GEM will see the contacts opening and closing as motor turns, then it deactivates the relay, stopping motor, when 4high contact pattern is seen, and THEN it turns on the 4high dash light, so there should ALWAYS be a delay from when you select one of the 3 positions until dash light comes on.
If dash lights flash that means GEM is confused or motor is not moving when it closed the relay.

The 4WD knob or buttons on the dash are just 3 resistors, GEM sends this switch a steady voltage, the return voltage thru ONE resistor tells it what the current selection is, when switch setting is changed GEM voltage changes, and it will then move shift motor.

You can operate the shift motor while it is off the transfer case to test if its working, it doesn't need to be Grounded to the vehicle

An just FYI the transfer case shift rod may not stay in 2WD with no shift motor in place there is nothing holding it there


1998 GEM and 4WD wiring diagrams here: https://therangerstation.com/forums/showthread.php?t=162915
Check fuses first




In 1998, Rangers got PVH front hubs, Pulse Vacuum operated locking Hubs
These were a bad idea and Ford dropped them completely by 2001
But if your front driveshaft wasn't turning in 4WD then Hubs are not the first problem to address
Troubleshooting PVH here: https://therangerstation.com/tech_library/troubleshoot-fix_pvh_hubs.shtml

Locking here: https://therangerstation.com/Magazine/Apr04/offroad.htm

Swapping them out here: https://therangerstation.com/tech_library/AVM_hub_swap.shtml

Alot of great information/interesting, easily explained so that even I can just about understand the majority of it with one reading.

So tell me where to start, Ill do that and come back and report my findings.

Did you say fuses, Ok where would they be located?

 

[1930]

And just out of curiosity how do I remove that 8th wire, the black one, I see no disconnect if the motor did have to be replaced.

 

[Uncle Gump]

Ron... you ever tried counting cards? If so... pack your bags buddy. We're headed to Vegas!

You have like a photographic memory.

The ranger world is lucky to have a guy like you... and your willingness to share your knowledge... that's just priceless

 

[RonD]

And just out of curiosity how do I remove that 8th wire, the black one, I see no disconnect if the motor did have to be replaced.

You have to cut it and then splice it back together
You can fit it with a connect/disconnect for "next time", but shift motors should not be failing that often

Common cause of shift motor failure is disuse, so best practice to shift into 4 high and then 4low and then back to 2WD while just sitting in the driveway
Do this once a month, this keeps the motor brushes clean, most common issue is failed brush contact.
Also spreads out the grease again on the worm drive

I would start by checking the fuses shown in 4WD wiring diagram, then with shift motor, see if it moves

 

[RonD]

Ron... you ever tried counting cards? If so... pack your bags buddy. We're headed to Vegas!

You have like a photographic memory.

The ranger world is lucky to have a guy like you... and your willingness to share your knowledge... that's just priceless

You are very kind, thanks

But I don't always get it right, so grain of salt

 

[1930]

You have to cut it and then splice it back together
You can fit it with a connect/disconnect for "next time", but shift motors should not be failing that often

Common cause of shift motor failure is disuse, so best practice to shift into 4 high and then 4low and then back to 2WD while just sitting in the driveway
Do this once a month, this keeps the motor brushes clean, most common issue is failed brush contact.
Also spreads out the grease again on the worm drive

I would start by checking the fuses shown in 4WD wiring diagram, then with shift motor, see if it moves

I have printed out the diagrams you posted, electrical is my weak point!

I see at the top of one page it shows what im assuming is a fuse, it says at top hot at all times then within box says fuse 13 20A, outside of box says I/P fuse panel?

I dont know what this means or still where exactly to find it? Can you explain to me?

Dosent look like any more fuses on this page.

Second page shows what Im assuming are 4 fuses in a row, also says I/P fuse panel?

So it seems like in one unknown location I will find a single fuse and prob within that same box Ill find 4 others? Does that sound correct?

Can you help me to understand?

If Im understanding correctly than if my fuses check out properly than you are telling me that when I turn the indicator switch on my dash that technically the motor should turn what it needs to turn even with it being disconnected and just sitting off the case?

Is that correct?

I dont think that will happen, Ive never heard any noise, Ive never heard ( or seen ) anything at all happen when I turned the knob on the dash, Ive never seen any indication of anything at all happening when I turned that knob on the dash.

The truck is super clean, I doubt its even been used, ( 4 WD I mean ) unfortunately the truck was not cared for from what I can see, Im knee deep in ALOT of issues with it but Im hoping to get them sorted out one at a time.

Im a car/truck guy, I dont give up easily and anyway Ive already got more into the truck than it will ever be worth so why stop now

I can and will eventually get this!

 

[ericbphoto]

That would be fuse #13, rated for 20 amps, located in the fuse panel inside the cab of the truck. That fuse panel is often located on the driver side under the dash or maybe in between the dash and the door. If you have the owners manual, it should tell you exactly where to find it along with a complete list of the. Fuses in that panel and a picture showing where each fuse is within that panel.

Yes. The motor should move even when not bolted up to the transfer case. When putting the motor back on the transfer case, you will need to make sure that it’s shaft and the transfer case shaft are in the same position. Ie; 2wd or 4hi, etc.

 

[1930]

That would be fuse #13, rated for 20 amps, located in the fuse panel inside the cab of the truck. That fuse panel is often located on the driver side under the dash or maybe in between the dash and the door. If you have the owners manual, it should tell you exactly where to find it along with a complete list of the. Fuses in that panel and a picture showing where each fuse is within that panel.

Yes. The motor should move even when not bolted up to the transfer case. When putting the motor back on the transfer case, you will need to make sure that it’s shaft and the transfer case shaft are in the same position. Ie; 2wd or 4hi, etc.

Thanks very much, I'll check these things out when sun comes up

 

[1930]

I checked the fuses with a test light and they are good, I started the truck and had my wife move the knob in park with her foot on the brake and the motor does nothing?

What should I do next?

 

[RonD]

I/P fuse panel is in the cab as Eric said

When you turn on the key there will be a "Bulb test", all warning and information lights should come on for a few seconds, then go off if they are not activated by their controller, this can tell you if a bulb is burned out.
This test includes the 4WD lights.

If the shift motor doesn't turn when knob is turned 4WD lights should Flash if GEM is working.
The GEM is the controller of the 4WD system, the 4x4 module and shift motor are the devices it controls
The "knob" tells GEM what Driver wants

So if GEM is working the 4WD lights should flash if 4x4 module or shift motor is not working

When you select 4high or 2WD with the "knob" you should hear a relay in the dash "Click", in the 4x4 module, to activate the shift motor
Don't use 4low for testing since it requires other parameters to be met to work, system can shift between 2WD and 4high at any time, i.e. in gear/in neutral, at speed, under 50mph, so best to use these for testing

In your original post you mentioned Flashing 4WD lights, but that they stopped flashing?
This made me think GEM was working but a fuse had blown

 

[1930]

Hi

I/P fuse panel is in the cab as Eric said

When you turn on the key there will be a "Bulb test", all warning and information lights should come on for a few seconds, then go off if they are not activated by their controller, this can tell you if a bulb is burned out.
This test includes the 4WD lights.

If the shift motor doesn't turn when knob is turned 4WD lights should Flash if GEM is working.
The GEM is the controller of the 4WD system, the 4x4 module and shift motor are the devices it controls
The "knob" tells GEM what Driver wants

So if GEM is working the 4WD lights should flash if 4x4 module or shift motor is not working

When you select 4high or 2WD with the "knob" you should hear a relay in the dash "Click", in the 4x4 module, to activate the shift motor
Don't use 4low for testing since it requires other parameters to be met to work, system can shift between 2WD and 4high at any time, i.e. in gear/in neutral, at speed, under 50mph, so best to use these for testing

In your original post you mentioned Flashing 4WD lights, but that they stopped flashing?
This made me think GEM was working but a fuse had blown

At this point both four-wheel-drive lights are flashing on the dashboard again as I'm driving it.

4 High and 4 Low turning the knob on the dash does absolutely nothing to affect the motor that's disconnected from the transfer case and that I have zip tied to this Shield