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1997 XLT 4x4 Trouble


RonD

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YUP, if it still doesn't work when switching from 2WD to 4high then GEM is the issue at this point

4low requires other sensors to be active, but 2WD to 4high is "shift on the fly" so it just needs the 3v from switch and GEM should run the shift motor to 4high position

You could test in GEM is grounding a relay when 4high is selected
The Brown/pink wire at GEM or dual relay box should show 12v with key on
When you select 4high then that 12v should go away(brown wire grounded) and relay should click
This is assuming that diagram has correct rotation labels, lol

Shift motor should be moved Counter Clockwise(CCW) to get from 2W to 4high

If its mislabeled in diagram then the Grey wire would go to 0volts when GEM grounded it and relay clicked
 
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PeteFleck

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My only other question would be whether the wiring between the GEM and the 4x4 module could be the issue? Unlikely?

Thank you again for all your help.. would’ve been totally lost!!
 

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Sorry Ron.. add one other question to that.. if I go ahead and purchase a used GEM with the same part number (F67B-14B205-EA), there should be no issue plugging it straight in? No programming or anything wild like that required?
 

RonD

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The relay would still "click" if the shift motor was the problem, or the wiring to the shift motor

In 1997 there would be no programmable differences
Just 1998-2000 GEMs needed tire size changes for speedometer calibration

F6 = 1996 so you have an early build 1997, not that it matters, but that same part number could have been used in 1996 and 97, that would be my guess since there were no changes in those 2 years

The EA at the end would be the digits that need to match

F67B = 1996 (7)Ranger/Mazda (B)electric part
14B205 = Ford part number for GEM module in ANY Ford Model
EA = Revision number, also can be software code loaded when new
 

RonD

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Worth testing the two wires, grey and Brown/pink
 

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Morning Ron,

I’d be testing these wires for ground? Correct?

Presumably, if I’ve done the other tests correctly and ruled out the switch and the relay as being bad, this test will fail, and confirm that the GEM is not communicating with the relay?


Thanks again,

Pete
 

RonD

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Well yes if testing live, key on, both wires should show 12volts, that's the power passing thru the coils of the relays from fuse 27 to the light green/orange stripe wire

Then the 12v will drop to 0v on one wire if GEM grounds that wire

But you could also just test continuity of the two wires
 

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Hi.. I’ve seen and read lots of posts on this particular problem, I just want to clarify a couple of things to hopefully save myself some time..

I have the classic issue of the 4x4 lights flashing 6 times every 20 seconds or so, indicating a 4x4 issue. 4x4 will not engage.

I started with fuses in driver’s side panel as well as distribution box under hood. All good. Next, I took a gamble on the transfer case shift motor being bad, switched it out, no change.

Everything now points to an issue with the GEM, or the Electric Shift Control Module, both centred behind the dash so I’m led to believe.

I haven’t been in there yet, but I started researching whether I could track down either of those parts, as both are obsolete from the dealer.

I can get a GEM, but nowhere can I seem to find a replacement Electric Shift Control Module (which I’ve read is essentially a couple of relays in a small box located close to the GEM).

Does anyone have any suggestions? Also, my gut instinct tells me that if it was the GEM that had failed, I would be seeing other issues with my trucks electrical functions besides the 4x4?

Any help greatly appreciated!

- Pete
Have you checked the hubs? Try shifting the T-case manually.
 

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Morning Ron,

Thought I’d send you an update!

I ran those tests you described above and found 12V at both the Grey and the Brown/Pink wire at the relay.. when the switch was turned from 2WD to 4Hi neither wire was grounded.

I also ran the resistance and voltage tests on the switch again to double check it. All good there.

So.. I have ordered a GEM module (same part number) from FN99 in Campbell River, astronomic shipping to get it up here, but it is on its way!! I will keep you posted..


Thanks again for all your help,

Pete
 

RonD

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Good stuff, nice testing
 

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Evening Ron,

Brace yourself.. bit of an update..

So.. the GEM from FN99 finally arrived a couple of days ago, but it took me until this evening to find time to install it. I disconnected the battery, removed the old GEM, installed the new one and.. still no 4x4, and now I also have intermittent wipers and flashing dome and glove box lights!

The GEM from FN99 must be faulty?

This leads me on to my next discovery. While I was waiting for the new (used) GEM to arrive, I noticed that when I fired my truck up I could hear 4 clicks coming from behind the dash before the 4x4 lights begin to flash. What I’m now wondering is whether once the GEM establishes that there is a fault with the 4x4 system, it will not try and activate the shift motor when you turn the switch until you turn-off the engine and start the sequence over, which is when you hear the relay clicking as the GEM tries again to activate the 4x4? Does that make some sort of sense?

If this was the case, firstly, the tests I ran between the GEM and the relay would fail (unless I did them immediately after firing up the truck while the GEM was trying to activate the 4x4) and secondly, it would point to the issue being further down the chain.. probably back with the shift motor which was where I started?

When I installed the new shift motor.. a while ago now, lying in a puddle under my truck, it proved to be quite a struggle as the keyway was very tight on the shaft? I also did not take the time to pull the old one apart and check to see if the nylon ‘stop’ bushing had failed (I believe that this is normally the issue), and so I can’t confirm that the old shift motor was either bad or good. I just took a punt.

I now questioning whether the shift motor wasn’t the problem after all, and whether the new one I put on isn’t bad as well?


If you can make any sense out of my ramblings I would appreciate any ideas you had.


Thanks in advance,

Pete
 

RonD

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New GEM reads like it is bad

Yes, if the GEM can't "see" what position the shift motor is in with key on it would flash 4x4 lights and yes it would not shift because it doesn't know where to move the shift motor, its "lost"

There are 5 wires on shift motor's contact plate, contacts show what "gear" transfer case is in, 2wd, 4high, neutral, 4low, yes there is a neutral position just not select-able on the switch, there was a kit you could buy to add Neutral, mainly used for flat towing behind an RV, it was a button added just below the dash

Contact wheel seen here: https://www.explorerforum.com/photopost/data/500/27133Tcase08.JPG
Contacts seen here: https://www.explorerforum.com/photopost/data/500/27133Tcase04.JPG

Only 5 contacts are used, needed
You can see in the 1997 4WD drawing the Yellow/white wire is the "voltage", the OUT
Then there are 4 wires for Contacts A, B, C and D that will be closed, sending voltage back to GEM on their 1 wire

I can't say I have ever tested what contact or contacts are "closed" in each position

Shift motor does not need to be bolted to transfer case for testing, so you could pull off the shift motor and plug it into the harness, then turn key on and see if it will move a bit as relays click, and GEM tries to "see" starting position of shift motor

The wires are the same colors from 8 pin connector to GEM so you could test each wire for continuity, maybe one is bad
Also with GEM plugged in and key on test the yellow/white wire at connector, I am curious to see if its 5v or 12v or maybe even a Ground reference and not voltage at all
 

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Morning Ron,

The latest from Haida Gwaii.. so, I finally got around to doing some more tests. When I removed the shift motor and worked the dash switch, there was a little movement from the motor before the lights on the dash began their flashing sequence?

Any thoughts on where to go from here? A friend of mine mentioned to me that he had heard of a few instances where the dash switch had checked out as okay with the various multimeter tests, but when it had been changed out with a new one the problem was solved?! If this was the case with my truck, if the switch was in fact faulty, would I still be seeing this movement in the shift motor?

I guess my other thought is that there might be a cracked/damaged wire ‘downstream’ from the control module/relay, allowing some power to reach the shift motor, but not enough to actually allow it to function properly? Do you know where that wiring runs in my truck?

Any suggestions on where to go from here would be much appreciated!


The mystery continues.. cheers,

Pete
 

RonD

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Flashing 4WD lights mean either the shift motor is not moving when GEM tells it to, or the GEM is not seeing the Contacts in the shift motor changing

Have a look here: https://www.therangerstation.com/tech/rebuilding-a-ford-transfer-case-shift-motor/

In the 1st and 2nd pictures you can see the 7 wires for shift motor
The yellow and orange wires are the 12volt and Ground wire that power the motor itself

The other 5 wires are the Contacts, "position sensor"
Picture 5 shows the contact plate that turns when motor and transfer case shift rod turns
Picture 6 shows the Contacts that sit on that plate
The GEM module uses the contacts "opening" and "closing" as they touch the metal parts of the plate to "see" the position of the transfer case, 2H, 4H and 4L

So GEM powers the motor then "watches" for contacts to open and close, if it doesn't see that instantly, it will shut off the power and flash the 4WD lights, because it is Lost and doesn't want to damage anything

I would first pull out the shift motor unit so you can test the motor by giving it 12volt and ground, the motor turns in BOTH directions, same as power window motor does
Yellow wire 12v
Orange wire Ground(battery negative)
Will turn motor one-way
Reverse these, Y = N, O = 12v and motor turns the other way

The motor does have a STOP just under the contact plate, seen in picture 8, motor can get stuck there if it rotates too far

So test if the motor can move in BOTH directions using car battery
(if there is a brown wire on connector cut it so you can get shift motor out, then splice it back together on reinstall, its for the electric clutch inside transfer case)

If motor seems to move just fine then you will need to open up the top and have a look at the contact plate and contacts, clean BOTH so you have good metal on metal contacts
Plug shift motor back in to harness and test if will now work

With key on, if switch was left in 2WD position then GEM should move the shift motor to 2WD position, so it doesn't matter where you left the shift motor after testing, it should "reset" to switches position if motor/contacts and GEM are all working as they should
Then try 4high, and 4low(4low does require foot on the brake and trans in Neutral)

The shift motor case doesn't need to be grounded to the vehicle to work, just FYI
Brown wire doesn't need to be reconnected until shift motor is reinstalled on transfer case, it won't prevent shifting when testing
 
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