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Strange 4x4 switch problem


sunnyboy

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I have a very odd 4x4 switch problem with my 2008 Ranger FX4 (4.0L V6). All the various internet posts about 4x4 always talk about it 'not engaging'...

Well, mine engages immediately without any problem. HOWEVER, it does not easily DISENGAGE. If I put it in 4H, and then switch back to 2H, it stays in 4H for anywhere from 5 min to 10 min or more. I have to drive it (any speed) forward for that time until it finally 'releases' and goes back to 2H.

It's more annoying than serious, as I can always drive for a while in 4H as it's usually that kind of weather (snow) when I need it. But it's still frustrating.

I've read about the contact wipers inside the actuator of the transfer case getting dirty, but that's always related to the 4H 'not engaging', rather than the reverse.

Any suggestions? Thanks in advance.
 


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RonD

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In 2001-2011 the Ranger 4x4s have 3 parts used in electric shift
Switch
4x4CM, control module
Shift motor

The switch in the dash is just 3 resistors
4x4CM sends the switch 5volts on 1 wire, key on
If 4x4CM gets back 4volts on the other wire, then it knows switch is in 2WD setting
3volts is 4high setting
2 volts is 4low setting
So pretty simple 2 wire setup

The 4x4CM is the "brains", it has 2 relays to make the 2 shift motor wires + and - so it can turn it either way(like power window motor)
It has 5 contact wheel wires so it knows what position the transfer case shift rod is in

Shift motor is just an electric motor with reduction gear that turns the shift rod and contact wheel until 4x4CM turns off the +/-

So best guess would be 4x4CM is not reading switch voltage correctly
Possibly the switch but I think you would get unwanted activation not slow activation

In 2008 the 4x4CM is behind the radio, you could test voltage on the switch wires
test using a volt meter and a sewing needle to pierce a wire while its still connected to 4x4CM

If switch voltages read correctly then 4x4CM is the problem


2010 diagram is the same as 2006-2011
 

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sunnyboy

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Thanks for the great info! In my case I forgot to mention that when it won't switch back, you can move the switch from 4H to 2H and nothing happens. Then, while driving down the road a bit later I hear a click (the relay I bet) and then I'm in 2H.

That does sound like the 4x4CM.
 

RonD

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Its actually the most likely part to fail
The 2001-2005 4x4CMs were worse, Ford used a newer design for 2006-2011, but never did solve it completely, but way less failures

And just as a heads up, shift to 4high then 4low and back to 2WD once a month just sitting in the driveway, what causes the shift motors to fail is just sitting for months and months between use, the electric motor brushes lose contact so motor just stops working, and you won't know it until you NEED IT, lol
Using it once a month keeps the lube spread out, contact wheel clean and the brushes clean
 

sunnyboy

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Thanks Ron. Good info to know. Of course I haven't been exercising the 4x4 functions at the moment as it's no fun being stuck in 4L... ever! ;-)
 

RonD

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Worse case is you take off the shift motor, 3 or 4 bolts, and manually turn transfer case back to 2WD or 4high, which ever you want, then test shift motor while its off
 

Bracket racer

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Excellent info Ron. I had the same issue, sometimes wouldn't engage, other times wouldn't release.

My fix was to pull the motor and bolt a plate on locking it in 4low. (course it's an "off road only" crawler, LOL!)

36300
 

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