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98 4x4 module/GEM wiring


freestyletrev

15+ Year Member

Joined
Jun 30, 2015
Messages
6
Points
1,501
Vehicle Year
1998
Transmission
Manual
Hello,
I've posted about this before, but in a less specific way.

I have a 98 xlt, 4x4 5spd. I can shift into 4 high fine. When switched to 4 low, no relay clicks, no flashing lights. I've taken the motor off and it will turn either way with 12v and the tc can be turned in 4 low. I imagine this is a sensor issue. (speed, brake, clutch switch)

My brake lights work, and I can start the truck only with the clutch pushed in fully, so I imagine those sensors are fine. The speed sensor is probably/ hopefully the culprit.

Can anyone tell me what wires going into the GEM are for the speed, brake, and clutch sensors so I can just run ground/12v to them when I want to shift to 4 low?
 
Here ya go.
Clutch switch isn't just one switch, there are 3 switches in it, so in theory one of the switches could be broken and engine would still start, but longshot
 

Attachments

Thank you so much for the diagrams!

Would you happen to have diagrams for the 4x4 module also?

I don't see where the GEM has a clutch sensor input; just brake and speed. I know the clutch switch that I know of is located on the clutch pedal assembly. Where are the other parts of it? Included inside that assembly?
 
Some of the diagrams wiring don't match up. I will have to wait until I can look at my wiring on my truck this weekend. This might be a life saver for me though! Thank you so very much!
 
RonD said:
Here ya go.
Clutch switch isn't just one switch, there are 3 switches in it, so in theory one of the switches could be broken and engine would still start, but longshot
Click to expand...
Hey Ron, new here and doing some research and came across your pdf links and on the 98 GEM 2 pdf, I have a question if you don't mind me asking. On the C223 plug, terminal 12, yel/wht wire color, 4WD output. When that is plugged into the GEM, I get 0 ohms (short) between ground and that yel/wht wire. If I unplug this plug from the GEM, the short goes away. I started checking at the transfer case motor connector first for the short to ground on the yel/wht wire and found the plug under the seat, so that's when I unplugged it there and checked from there back to the GEM. Again, the short goes away if I unplug the yel/wht wire from the GEM. Is this normal? The reason I ask is I installed a new transfer case motor. I checked to make sure it worked before mounting it and it did. After mounting it I started getting the blinking 4WD High and 4WD Low lights on the dash, six times every 2 minutes. So I took the transfer case motor off and tried to work it with the 4WD selector switch and it did not work. 1998 Ranger 4.0L XLT
 
RonD hasn't been online in over a year. Unlikely we'll hear from him again.
 
Depending on the state of the relays in the controller (GEM), you could see a ground reading in that yellow wire. That wire goes through a relay to the motor windings, then back through the other relay to be connected to either ground or 12volts, depending on which direction the motor needs to spin.
 
Curious Hound said:
Depending on the state of the relays in the controller (GEM), you could see a ground reading in that yellow wire. That wire goes through a relay to the motor windings, then back through the other relay to be connected to either ground or 12volts, depending on which direction the motor needs to spin.
Click to expand...
Thanks, yeah I finally figured out after studying the wiring diagram that this can show up as a short. I've been researching a little more and have learned more about "switched ground" and "switched power". Just makes it more confusing for a guy that has done alternating current all of his life. I did get around to doing a continuity test on the 4x4 selector switch and also checked the three different voltages as you switch between 2H, 4H, and 4L on it also, all were good. Checked the solder joints on the electric shift control module, they looked good as well. I was able to get the shift motor to work when I cleared the codes and operated the 4wd mode selector switch while the relays in the shift control module were clicking, but after the relays stopped clicking, I'd get the 4wd high and 4wd low lights blink on the instrument cluster 6 times every 2 minutes. I changed the shift motor about a week ago. I'm leaning towards that shifter motor even though it's new or the wiring between the GEM and the shifter motor.
 
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