1997 XLT 4x4 Trouble

[PeteFleck]

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

 

[RonD]

Welcome to TRS

I assume you have disconnected battery to reset all the electronics?

Yes, if it was the GEM then the 4WD lights wouldn't flash most likely, because the GEM is what does that

The dual relay box is behind the GEM, its what you should hear "click" when transfer case shift motor is used
There is 1 relay for 1 shift motor wire, so 2 relays
Both shift motor wires are grounded when relays are off
So the GEM only needs to activate 1 relay to change that 1 wire from ground to 12volt, which causes the shift motor to move clockwise(other wire is already a ground)
Then activate the other relay to move shift motor counter clockwise

It is possible the GEM is not activating the relay but wouldn't expect the flashing 4WD lights in that case
The flashing lights usually mean GEM has activated a relay but shift motor(contacts) are not changing position, no motor movement

So if you are not hearing the "click" from the relay then either GEM is not activating it or relay is not working or unplugged
The 2 Relays send the 12volts from the one fuse in engine bay fuse box to the shift motor, the cab fuses power the GEM

Try this part number: F57B-6912-AA

Should be the same for 1995-2000 Rangers and Mazda B-series 4x4s

Explorers used similar from 1995-1998 but has a different revision number, F57B-6912-BA
Same housing and connector but not sure on wiring, they don't cross reference

Wrecking yards might have these but just don't pull them out so check if they have 1995-2000 ranger/mazda 4x4 and you may get lucky
It is not a common failure part, so used is usually a safe bet

 

[PeteFleck]

RonD.. thank you so much for your speedy reply! Really helpful. I will get to work and report back!

 

[PeteFleck]

Hi Ron.. pulled the dual relay box.. anyway to test with a multimeter? Or would that not necessarily identify it as the problem?

 

[RonD]

Yes, you can use an OHM meter and a 9v battery to test

1997 wiring diagram below

It does have a mistake in that the upper relays "load" pin should be connected to the Black Ground wire same as lower relay shows, but not important for testing

Its a 10 pin connector and you can use the Black wire to ID pin 1 and Orange wire to ID pin 10 so you will know pin numbers from that

The light green/orange wire on pin 5 will have 12v with key on, then the GEM uses grey wire(pin 8) as a ground to activate that relay
Then Brown/pink wire(pin 9) to ground the lower relay activating it

So if you ohm pin 5 to pin 8 you should see under 50 ohms, same for pin 5 to pin 9
If not relays coil is bad

Or you can connect battery to pin 5 and 8 and should hear relay "click" and same for 5 and 9 should get "click" from other relay
There is no polarity on a relay's coil, as long as one pin is + and the other - the relay will "click" closed

You can test other pathways thru the relays load side, but if you are not hearing the "click" when changing 4WD switch position the fault would be on a relays coil side, not the load side, for now anyway
Or in the GEM not grounding pins 8 or 9 to activate relay
And check green/orange wire(pin 5) for 12v key on, if no 12v then no relays

 

[PeteFleck]

Hey Ron,

Again, hugely helpful. Thank you.

The ohm reading between pin 5-8 and pin 5-9 gave readings of 102 and 103.3 respectively.. would we take this as definitive that this is the culprit?

Thanks,

Pete

 

[RonD]

Actually that should be fine, never test those relays but as long as they are not "open", 3,000+ ohms, then they should be OK
Was thinking solenoids, 50-300ohms for 12volt relays is OK

Test with 9v or 12v to make sure

And since relay coils look good check if you have 12v key on at light green/orange wire

 

[PeteFleck]

Hey Ron,

I have 12V with key on at green/orange wire.. I haven’t tested relay with 9V yet..

Where do I go next?


Thanks,

Pete

 

[RonD]

I would try testing with 9v battery or the 12v(pin 5) and ground(pin 1) wires on 10 pin connector with jumper wires to pins 5 and 8 and then 5 and 9 to see if relays "click"

Plug the relay box back in and then try shifting to 4WD and back to 2WD, see if relays "click"

 

[PeteFleck]

Morning Ron..

Okay, tested the relay as described.. it clicks! Plugged back into truck/GEM, shifted between 2WD and 4WD.. nothing, just flashing lights on dash, same as before.

What’s the next step/what do you suggest?



Thanks,

Pete

 

[RonD]

Its looking like GEM module issue

You can test the switch at the GEM module wires to see if it has the correct OHM readings
From a member here
3.86v and 3,870 ohms for 2wd,
2.94v and 1,090 ohms for 4wd high
1.76v and 357 ohms for 4wd low

Or you can test voltage

The switch uses a 5v scale but its a pull down circuit

Test OHMs with Key OFF
At the GEM there is a grey/red wire on pin 21 on Connector 221
And a white/light blue wire on pin 8 C224

Unplug these connectors and put OHM meter between the 2 wires
Move the 4WD switch to its 3 positions and you should see above OHMs

This tests the wires and the switch
So would confirm GEM is "seeing" correct change in voltage when switch is moved, or confirm its NOT

If switch is working and Dual Relay box is working.............................then you are down to GEM not working, but it really surprises me that it flashes the 4WD lights if its in a failure mode

 

[PeteFleck]

Hi Ron,

So, just before I saw your reply, I tested the dash switch for continuity...

With the switch in 2WD position, there was continuity between the 12V pin and the 2WD pin.. when I then changed the switch to the 4WD High and 4WD Low positions, there was no continuity between the corresponding pins and the 12V pin.. does this tell me I have a faulty dash switch?

If so, would it correlate with the flashing lights on the dash? I.e. would the GEM recognise the failure of the dash switch?

Thanks,

Pete

 

[RonD]

12v pin(red/black wire) on 4WD switch is for the back light, illumination

Grey/red and white/blue wires are signal, they should read OHMs as above or "continuity" in all 3 positions if that's all you have
As said its a 5volt circuit

 

[PeteFleck]

Hi Ron,

Okay, so I went back in behind the dash and here’s what I found..

Ran a continuity test on the grey/red wire and the white/blue signal wires.. they checked out good.

Next, with key OFF, I set my multimeter to 200ohms and tested resistance between the grey/red and white/blue wire, shifting the dash switch between 2WD, 4Hi & 4Lo as I went. I got nothing, no reading.

I then turned key ON and tested for voltage on the grey/red and white/blue wires. Again nothing.

Does this point to my dash switch? Would a faulty dash switch cause the GEM to flash the 4X4 lights?


Thanks,

Pete

 

[RonD]

Set OHM meter at 20,000 ohms, 20k ohms

Yes, if the GEM doesn't see any voltage passing thru the switch when key is on that would be a fault that would cause lights to flash

Test grey/red wire for DC Volts, should be about 5volts, put meters black probe on a good ground, dash metal, Red probe on grey/red wire, key on
Then move red probe to white/blue wire