Hello I am new here and so far have got lots of good info. But I am stumped . What I have is a 1997 f150 with the esof. We have replaced the shift motor, GEm and every ting you can think of. What we have discoverd now is the Gem needs to ground the relay wire and there has to be a switch to tell the Gem to do so.( on the trans or transfercase) ??????????? If anyone knowes where this switch is located I would be realy happy. Thanks Jeff

 

Does this help?

Electronic Shift On the Fly (ESOF) Operation
The ESOF system is an electronic shift 4x4 system that allows the operator to choose between two different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD and 4WD HIGH mode at speed. To engage or disengage LOW Range, the vehicle speed must be less than 5 kph, the brake depressed, and the transmission must be in NEUTRAL.

The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4x4 High mode at speed. When the control switch on the instrument panel is turned, the generic electronic module (GEM) recognizes that a shift has been requested and activates the electromagnetic clutch and the relays which power the transfer case shift motor. When the shift motor reaches the desired position as determined by the contact plate position inputs to the GEM, power to the shift relays and motors will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.


Shift Between 2WD and 4x4 HIGH:

Shifts between 2WD and 4x4 HIGH can be made at speed. Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.

Feature Inputs:

l 4WD Mode Switch (Various resistances; See «Table 1»).

l Contact Plate Position Inputs A, B, C, D (grounded when closed, open circuit when open; See «Table 4»).

Feature Outputs:

l 4x4 Shift Motor Relay Outputs (See «Table 2»).

l Transfer Case Clutch Relay (grounded when relay is on, open circuit when relay is off).

l 4x2/4x4 Vacuum Solenoid (grounded when activated, open circuit when deactivated).

l Cluster Indicators (ground when activated, open circuit when deactivated).


Shifting Into/Out of 4WD LOW:

When shifting into or out of 4WD LOW, the GEM requires that the vehicle speed be less than 5 kph, the brake is applied, and the transmission is in NEUTRAL.

Feature Inputs:

l 4WD Mode Switch (Various resistances; See «Table 1»).

l Contact Plate Position Inputs A, B, C, D (grounded when closed, open circuit when open; See «Table 4»).

l VSS Sensor (Sinusoid Signal: 0.7V-20V, 2.2 Hz/mph).

l Brake Input (battery voltage when brake is depress, open circuit when not activated).

l Transmission Range Sensor (grounded when transmission is in NEUTRAL, open circuit otherwise).

l Start/Clutch Depressed Input (See «Table 3»).

Feature Outputs:

l 4x4 Shift Motor Relay Outputs (See «Table 2»).

l 4x2/4x4 Vacuum Solenoid (grounded when activated, open circuit when deactivated).

l Cluster Indicators (grounded when activated, open circuit when deactivated).


4WD Mode Switch

A rotary switch allows the vehicle operator to choose between 2WD, 4WD HIGH, and 4WD LOW modes of 4x4 operation.


GEM Module

The Generic Electronic Module (GEM) controls the operation of the 4x4 system (See «ESOF Operation» for details).


Vehicle Speed Sensor

The vehicle speed sensor (VSS), mounted in the rear of the transfer case, informs the GEM of the vehicle speed.


Transfer Case Shift Motor Sense Plates

The shift motor sense plate, an integral part of the electric shift motor, informs the GEM to the positions of the transfer case (See «Table 4»).


Transmission Range Sensor

Located on the left side of the transmission, this sensor informs the GEM when the transmission is in the NEUTRAL position.


Electric Shift Motor

The electric shift motor, mounted externally at the rear of the transfer case, drives a rotary cam which moves the mode fork and range fork within the transfer case to select between the 2WD, 4WD HIGH, and 4WD LOW positions.


4x4/4x2 Vacuum Solenoids

These two solenoids are attached to the upper RH side of the engine compartment dash, and alternately route vacuum to the vacuum motor which engages/disengages the center axle disconnect collar in the front axle assembly.


4x4 Shift Motor Relay

A module containing two relays which under the control of the GEM, shift the transfer case shift motor between the 2WD, 4WD HIGH, and 4WD LOW modes.


Transfer Case Clutch Relay

An electromechanical relay is used to activate the transfer case clutch within the transfer case.

 

Just out of curiosity does the "np" in your user name stand for North Pole?

 

Welcome to the forum Jeff.

 

I'll take a stab at that question
alaska p71
person form Alaska with a P71 (Crown Vic Police Interceptor)

 

Yep the alaskanp71 is because I have a Crown vic police interceptor and I live in Alaska. Thanks for the info I have gotten so far . I am hoping that I can get it fixed this weekend.

 

Ok, LastSplash, this may seem like a strange question, but i have a manual lever shift 4x4, and wish to convert to ESOF. I have an 03 5.4L FX4. What sorts of parts would entail this conversion, and would you happen to have acess to part #'s and cost? I realize that the reliability of the ESOF is always questioned, however, I do engage it regularly, and would like to get that stick out of the floor. I also realize that I will lose Neutral, as ESOF doesn't have it, but i am willing to make the sacrifice. I asked this on another ford forum, and was basically told it was a dumb idea, etc w/o being given an answer.

 

I am not sure how much it would cost but from looking at the service manual you would need to get a new t-case, the switch for the dash, and the wiring harness and that is just for starters. I am sure it is possible to convert your truck to ESOF but it would cost much $$$$.
As for the reliability of ESOF I have never had any problems with the ESOF on any Ford vehicles. The only difference between the manual t-case and the ESOF is that the ESOF t-case uses a motor to apply the low range instead of the mechanical linkage in the manual. Both t-cases engage the front driveshaft in high range the same way.

 

LastSplash....so what you are saying is that the electic shift motor does not engage the T-case into 4H...only into 4L?
Rich

 

Thanks for all the info . The problem is fixed.The new shift motor was bad.We instaled a ford shift motor and all is well now, Jeff

 

I've been having the same problem. 4x4 stopped working out of the blue, of course at the worst time. Started as a simple problem of no 4x4, then worked long enough to shift into 4Lo, but not out. Had to pull motor to shift back to 2Hi. Had some problems with the GEM last year (not 4x4 related) which went away when I had the windshield resealed. Thought it might have gone bad from corrosion from last year's incident, so I replaced it. I changed out the GEM module, but the problem still exists. The switch checked out OK with the ohm meter, with all readings within specs. Unfortunately, all the new GEM did was move the transfer case back into 4Lo. Gonna have to crawl back under, pull the shift motor, and manually shift it back into 2Hi. The last time I had to do this, I was able to move the slot on the motor to align with the shift **** on the transfer case by applying power to the orange and yellow wire connectors on the motor. Would this eliminate the motor as the problem?

The only other possible problem source I can see would be the transfer case shift relay module. It appears that it's located in the dash, which would coincide with the 5 clicks that I'm hearing when I try the switch. I pulled the oval panel off the top of the dash, but could not see it through the opening. Is there a trick to getting to it? If it's one of those impossible to reach parts, is there a way to test it from other connector points? Does Ford have a tester that will narrow it down to the correct component?

 

Minimonster,,,why on earth would you want to change over to the switch on the dash ? Both system's are Shift On the Fly, On the 97' and up F-150, and you have the most reliable setup now,,the manual shift !

If it's stiff, or hard to shift,,,get under there and spray the linkage with WD-40 or your favorite lube.

Theres probobly a 50 : 1 ratio, for post's on here of ESOF troubles, compared to manual shift, or MSOF, Most truck's/ Suv's have the ESOF,,and when the Electric part quits,,,most all would love to have a shifter, to grab and engage or disengage when needed !

My son lucked out and found a MSOF on the first truck we called about, 4x4 did not work,,,it was a $36 oil switch,,and it works great now!

 

I love the convenience of SOTF. You need 4x4 to get out of the subs and onto the main roads since that's all the money they have to spend.

 

Does anyone know where the 4X4 shift relays are located, I was told there located under the dash, but does anyone know how to get to them???? and what they look like