I hoping someone could shed some light on this one. I picked up a 95 Ranger to give to my nephew who just turned 16. I got it cheap, it needs a few things. In any event I wanted to get it working properly for him. First problem, it will not go into 4x4. It has the switch on the dash to engage it. The 4x4 and 4x4 Lo lights are both on. Switching to 2H, 4h, OR 4L has no effect on anything. The first thing I did was buy the Ford Shop manual and electrical troubleshooting manual from Helm. I reviewed the circuit in the manual and checked all the fuses. It calls a Generic Electronic Module, which takes input from the switch and other items and turns on the dash lights as well as the motor on the transfer case to make the switch. I figure the first place to check to find out the problem is to back probe the connector on the GEM, except I can't find the GEM. Manual claims it is in the center of the I/P(Instrument Panel) so I dig around, and take some of the lower shielding off the dash, as well as the glove box and I see no GEM. Am I just not seeing it or can someone give me hint at where it is? Better yet, anybody had this problem and know the quickest way to troubleshoot and fix. I am getting frustrated fast here. One other item, how does the plastic panel around the radio and heater come off? I took off two bolts under radio, but it won't let go, what is the trick here?
Thanks in advance
JWR

 

If there's a GEM, then it's behind the radio.

 

Ok, I found the Gem module and started some pinpoint testing. If I ground the outputs, for the 4 wheel drive cw relay and ccw relays, the transfer case shifts and the truck can go in and out of 4x4. I checked the switch and it has the proper resistances in the three positions. What other inputs are necessary to make the Gem switch to 4x4? I should check all inputs before condemming the Gems. Do the Gem modules go bad, is this common? I feel there is some input reason why the Gem will not command the relays to switch? Any hints on this one?
Thanks
JWR

 

before you go into the whole electric thing...

is it manual or automactic locking hubs?

do you have a selector on the front 2 wheels, that you can turn? one saying locked, one side saying unlocked or something similar... if thats the case, turn the selector to locked, and then try it again...

if it has automatic locking hubs, try driving about a block, after turning on the 4wd button.... if it STILL doesnt work, it could just be the automatic hubs are bad... or arent ingaging, which does tend to be a problem with atleast s-10 blazers and trucks... i know i know this is a ford we are talking about, but it could also be the reason for you...

 

I can engage and disengage the 4 wheel drive by grounding the CW and CCW relay coils. This is the output of the GEMS module. The hubs are working. When I try to engage with the switch on the dash, no lights on the dash to show it is in 4x4 and the Gems is not grounding the relays to make the switch. This is most definitely an electrical problem. My question is what other criteria is necessary for the Gems to engage the 4x4 besides the switch position? If there is nothing, obviously the Gems is bad. Anybody been down this road before?
Thanks
JWR

 

I have a 1998 ranger with the switch on the dash, I locked mine into 4 low and it wouldn't shift out, and both my 4high and 4 low light's were flashing, it turned out to be the motor on the transfer case was bad.

 

Electronic Shift Operation, Ranger

The transfer case is equipped with a magnetic clutch, similar to an air conditioning compressor clutch, which is located inside the transfer case adjacent to the lockup sleeve. The clutch is used to spin up the front drive system from zero to vehicle speed in milliseconds. This spin-up allows the shift between 2H and 4H to be made at vehicle speeds listed in the vehicle owner's guide. The spin-up engages the front lock hubs. When the transfer case rear and front output shaft reach synchronous speed, the spring-loaded shift collar mechanically engages the mainshaft lockup hub to the chain-drive sprocket and the magnetic clutch is then deactivated. Shifts between 4H and 4L can only occur with the transmission safety switches closed. The vehicle's speed must also be within specified limits as determined by the Generic Electronic Module (GEM).

The electronic shift control system consists of a rotary switch control system, a GEM, an electric shift transfer case shift motor with an integral shift position sensor, a clutch pedal position switch or transmission range sensor, and a brake signal input switch.

Switch Control System

When the switch on the instrument panel is turned, there is a one second delay, then the electronic control module verifies the transfer case positions (2H, 4H or 4L). Next, the GEM looks at the shift position sensor and the transmission range sensor or clutch pedal position switch (depending on transmission type) and brake pedal switch. If all conditions are correct to allow the desired shift, the electronic control module will tell the electric shift transfer case shift motor to execute the shift. After the shift has been made and the electric shift transfer case shift motor is off, the control module again looks at the shift position sensor to make sure the proper shift has been accomplished. Finally, the dash indicator light on the control panel will be illuminated by a signal from the GEM indicating the desired shift has been completed.

GEM

The generic electronic module controls the operation of the transfer case in response to inputs to the rotary control by the vehicle operator, the shift position sensor, the transmission range sensor and the brake pedal switch.

Shift Position Sensor

The shift position sensor, an integral part of the electric shift motor, tells the GEM module the shift position of the transfer case.

Electric Shift Motor, Ranger

The electric shift motor, mounted externally at the rear of the transfer case, drives a rotary helical cam which moves the 2W-4W shift fork and 4H-4L reduction shift fork to the selected vehicle drive position.

 

Thanks Rockledge, This is the information I need. It's time to check the switches in the transfer case, brake and clutch switch operation.
Thanks again, I will let you know the results.
JWR

 

I finally fixed my problem. After checking the switches in the motor assembly at the Gems connector, it was found the switches were not changing if the motor was activated. I purchased a rebuilt motor and switches now work correctly and I have 4wd and 4wd low working fine. Thank you all for your assistance.
JWR