1991 Ranger 4x4 problems

[FordGirl143]

Hi, I bought a 1991 Ford Ranger xlt 2.9 4x4 in the beginning of the pandemic to fix up. Previous owner said the 4x4 worked just needed a fuse. But that was not the case. It was missing the whole transfercase module behind the drivers seat. I've read all the threads I could find and replaced the push button switch, engine/motor computer, transfercase module, shift motor. I was wondering if maybe the wires to the push button shifter are not in the right spots. Does anyone have a picture of the plug to the switch that shows the 8 color order? Is there another fuse needed somewhere I haven't checked or read about? Should I try replacing the speed senor? I'm now searching for The Shiftster but can't find that either to buy. Any help would be amazing thanks.

 

[Shadowrider6661]

Curious, is there a black wire coming out of the back of the transfer case ? I have a 97, and that black wire needs to be connected to the electric shift motor, or it won't engage into 4 wheel drive. I don't know about your year truck, so all I'm doing is throwing out something to consider. Welcome to the club.

 

[dvdswan]

Welcome to the site. This might help you.

https://www.therangerstation.com/tech_library/transfercasetroubleshooting.shtml About halfway down the page.

 

[RonD]

The dash switch only has 3 wires for control, the others are for lights

1993 diagram below should be similar to 1991

There is an electric clutch inside the transfer case, it has a single wire that comes out, usually a brown wire, its not integral to transfer case shifting or not, it was added for "shift on the fly", 2high to 4high and back when using Automatic Hubs
The clutch spins up the front driveshaft to engage/match it with rear output shaft rpms, when front drive shaft starts to spin Auto Hubs will engage
With manual hubs, locked, the front drive shaft would already be spinning at same rpms as the rear so no clutch/matching needed when shifting in and out of 2high and 4high
Just FYI

Shift motor is just a 12volt motor with 2 wires, apply 12v and ground and motor turns clockwise, apply ground and 12v and it turns counter clockwise, same as power window motors work

The other 5 wires on the shift motor are position "sensors", just contacts really, there is a plate with a metal pattern on it, when motor turns the shift rod the plate turns as well, this causes the 5 contacts to open and close in a pattern
2high has its own pattern, as does 4high, neutral and 4low
Yes there is a neutral its just not a selection with electric shift
The pattern is how the 4x4 control module knows which way to turn the motor and when to stop turning it
The shifter can't turn 360deg, it turns from 2high counter clockwise to 4H, N, and then 4L, 270deg, then it would turn clockwise back from 4L to 2H

The shift motor does have a stop and if it presses to hard on it it can get locked up
Good look at the shift motor parts here: https://www.therangerstation.com/tech/rebuilding-a-ford-transfer-case-shift-motor/

The Brown wire can be connected in the 8 pin connector, with the 7 other wires, or more often it was spliced to a separate brown wire on that same harness

I would pull off the shift motor and test that applying 12v/ground and ground/12v to the yellow and orange wires causes it to move, just use the battery in engine bay

Both motor wires on the truck side of connector should show as good Grounds to transfer case or frame metal with key off or on
Inside the controller are 2 relays for the motor's power wires, BOTH are grounded when off
So the controller only needs to activate 1 relay(12v) to power motor clockwise, because other wire is already a ground, and, of course, activating the other relay would turn motor counter clock wise
So if both show good ground then that wiring is OK

The 5 contact wires do need a good connection but...........the motor would activate, briefly, when switch on dash was activated, the controller would look for contacts to change instantly when it activated the shift motor, if it didn't see contacts change it would shut off the power to motor, and usually flashes the 4WD lights to indict a problem

 

[FordGirl143]

Thank y'all so much. I'll check to see about that black wire, I can't recall right now. I will be trying these as soon as I'm back in Texas on Monday!