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

[1930]

Hi
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

I would think that I would or should test that the motor is getting power or something like that before I assume the motor is bad.

I doubt the motor has been even rarely used

 

[1930]

Got to be a way to test the motor by giving power to it I just am unsure how to do these things

 

[Denisefwd93]

Got to be a way to test the motor by giving power to it I just am unsure how to do these things

Please re read post #4

 

[1930]

Ok sorry if I missed it already

 

[1930]

I read that post many times, thanks. So I need to look at schematic again, determine the wire colors leaving the fuse panel, check for continuity of these wires down to whatever the next device will be.

I'm assuming (don't have schematic in front of me ) that the wires will run down to the relay.

I need to see that relays open and close as they should and then continue to follow schematic checking for power.

 

[1930]

I'll look at it better tonight and see what I can see

 

[RonD]

If you have a Volt meter set it for DC volts

Unplug the shift motor connector and connect volt meter's 2 probes, one to the Yellow wire and one to Orange wire
Those are the 12v/Ground wires that power the motor
Key on
Change 4WD switch setting and see if volt meter shows +12v or -12v that means GEM is activating 4x4 Module and its relay is working, but shift motor is not

If you don't get +12v or -12v then 4x4 module is likely problem

The +12v or -12v will only be for a second or two, and it might come up +12 and then quickly change to -12, or visa versa.

The GEM expects instant feedback from the contacts inside the shift motor housing when it activates the relay, since the shift motor is not moving the contact wheel, the GEM stops sending voltage and sometimes reverses polarity to move motor back to its 'original position', because if contact wheel was the problem and motor was working then the driver repeatedly changing the knob would get 1 or 2 seconds of power at the motor and the transfer case rod would move, and could end up in between "gears" or even in Neutral.

So start at the motor end and see if wiring there is getting +12v or -12v on the yellow and orange wires

 

[1930]

If you have a Volt meter set it for DC volts

Unplug the shift motor connector and connect volt meter's 2 probes, one to the Yellow wire and one to Orange wire
Those are the 12v/Ground wires that power the motor
Key on
Change 4WD switch setting and see if volt meter shows +12v or -12v that means GEM is activating 4x4 Module and its relay is working, but shift motor is not

If you don't get +12v or -12v then 4x4 module is likely problem

The +12v or -12v will only be for a second or two, and it might come up +12 and then quickly change to -12, or visa versa.

The GEM expects instant feedback from the contacts inside the shift motor housing when it activates the relay, since the shift motor is not moving the contact wheel, the GEM stops sending voltage and sometimes reverses polarity to move motor back to its 'original position', because if contact wheel was the problem and motor was working then the driver repeatedly changing the knob would get 1 or 2 seconds of power at the motor and the transfer case rod would move, and could end up in between "gears" or even in Neutral.

So start at the motor end and see if wiring there is getting +12v or -12v on the yellow and orange wires

Very clear direction. Exactly what I was looking for

 

[1930]

I have a pretty good V.M at my shop. (Which I'm not familiar with using ) I'll drive out there and get it. Will post results tonight.

Thanks again

 

[RonD]

4x4 relay module is in the dash, it has the 2 relays inside it

The GEM module is behind the Radio, 4x4 relay module may be there as well, but could also be behind glove box, not sure in 1996
GEM module is working, i.e. flashing 4wd lights

Do you hear relay "CLICKS" when you change the knob positions?
If so relay box is working


If you tap on the motor part of the shift motor assembly you can sometimes break loose a stuck brush, this will get motor working again, but it is temporary, needs to be rebuild or replaced

 

[1930]

4x4 relay module is in the dash, it has the 2 relays inside it

The GEM module is behind the Radio, 4x4 relay module may be there as well, but could also be behind glove box, not sure in 1996
GEM module is working, i.e. flashing 4wd lights

Do you hear relay "CLICKS" when you change the knob positions?
If so relay box is working


If you tap on the motor part of the shift motor assembly you can sometimes break loose a stuck brush, this will get motor working again, but it is temporary, needs to be rebuild or replaced

When I turn the knob I hear absolutely nothing

 

[1930]

So does the truck have to be moving running and driving for anything to happen because up until now I didn't think anything was happening but I'm driving along now and I switched it from 2 wheel drive to 4 wheel drive high and I heard the relays click in the 4 wheel drive light Dash came on

 

[RonD]

Then you most likely will need to pull off the center console cover and pull out the radio.
Best guess is the 4x4 relay module is in that area
GEM will be on the left side, lots of wires and larger module
4x4 relay module is probably on the right, much smaller, maybe 3" square, and just a few wires, look for wiring colors on the diagram

 

[1930]

Then you most likely will need to pull off the center console cover and pull out the radio.
Best guess is the 4x4 relay module is in that area
GEM will be on the left side, lots of wires and larger module
4x4 relay module is probably on the right, much smaller, maybe 3" square, and just a few wires, look for wiring colors on the diagram

C post above

 

[1930]

Things seem eratic, I've never heard anything up to now when I turned knob