stuck in 4 low

[john cris]

Hello,
I put my 03' explorer in 4 low this morning coming up the boat ramp and can't get it to disengage. It's stuck in 4 low. This Explorer has a the automatic 4WD system with the 3 switches on the dash (4L, 4 auto and 4hi). How can I check the control module to see if it's working correctly?
Thanks,
Jcris
Here are the symptoms:
actuate 4 low switch and indicator light on switch flashes
light stops flashing after a few moments and then stays on
If I select 4 hi or auto the 4 low light stays on and does not shift

I hope that makes sense. I just want to figure out how to get it out of 4 low. Then I can at least use the vehicle until I figure out whats wrong.

 

[Machine090767]

Please tell me you have the brakes applied when switching back to 2wd from 4wd Low.

 

[TechGuru]

Well you can do the brown wire mod to use the vehicle in 2WD low up to 30mph without destroying the transfer case.

First I would check fuses related to 4x4 system.

Main two things that allow the gear change to start is brake pedal switch activated (brake pedal position sensor) and neutral switch activated (range sensor). I'd move the shifter around and try again.

If verified that both these things are working I'd set the parking brake and chock the wheels and have someone tap on the transfer case motor with a hammer while you push the 4x4 auto button repeatedly while in N and foot on brake because the next most likely thing I can think of would be the motor got stuck.

Here is the wiring:

 

[john cris]

Yes brakes applied. I was able to get it out of 4 low by tapping on the shift motor. Problem averted for the moment.
The transmission shifter on this truck is suspect. When I put it in drive the indicator needle doesn't rest in the middle of the "D" as it should. Sometimes I have to mess with it to get to drop into gear. I still need to check those sensors though

 

[TechGuru]

This is why I always say cycle all of your non daily used motors at least once a month. All windows + 4x4 hi/lo motor. What happens is corrosion develops between the motor's brush and commutator then electricity don't flow between them.

 

[john cris]

Point taken tech guru
I'll be taking it apart to see if it's repairable this weekend. Local parts place had reman for $162

 

[TechGuru]

Point taken tech guru
I'll be taking it apart to see if it's repairable this weekend. Local parts place had reman for $162

Probably just needs to be cleaned and lubricated. It's not like these get used enough to wear out very often.

 

[imp]

Yes brakes applied. I was able to get it out of 4 low by tapping on the shift motor. Problem averted for the moment.
The transmission shifter on this truck is suspect. When I put it in drive the indicator needle doesn't rest in the middle of the "D" as it should. Sometimes I have to mess with it to get to drop into gear. I still need to check those sensors though

Don't worry about the indicator needle. It is moved back and forth by a thin piece of cable, actually string of some fiber kind, returns to "P" driven back there by a tiny spring. Slightest amount of dust gets in there, or spring weakens, or breaks, needle will not return to P. If sticking, it may indicate wrong position, too. Ya gotta take the shrouds off the column to get at it, once seen it becomes pretty self-explanatory. But important thing is, it has nothing to do with the actual selection of the gears. imp

 

[john cris]

Thanks Imp

 

[john cris]

Thanks Imp

Well I got the shift motor out and took it apart being careful to mark for reassembly. This motor looks excellent. I don't see any signs of issues. The stop piece is not plastic. It appears to be a metal bushing to my old eyes. If it is plastic it's in good condition. There are no broken bits or shavings to be found anywhere. So I'm guessing the problem lies in the shift module. Are there 2 of those modules?
One in the glove compartment area and one also at the rear of the cabin, back near the hatch behind one of those covers? How can I test those modules?
Thanks for the help,
Jcris

 

[john cris]

Hey tech guru,
Thanks for the print, it really helped me verify correct location for re-pinning connector

 

[john cris]

I took a look at the control module in the glove compartment area and there's no self test indicator lights . So testing it comes down to a checking power in and out. I've checked some online content and see checks for early model explorers but not something newer.
Idea's?
Thanks,
Jcris

 

[rrgone]

Check to see if you have a good ground on the system. Ground wire (black) comes out of the pigtail on shift motor and attaches to frame. It has been known to rust and rot at mounting point on the frame. That can cause problems, not necessarily like what you are having, but worth a look.

 

[john cris]

hey rrgone,
Yup I checked that ground wire and it's good.
I'm going to pull that control module and open it up for a physical inspection.

 

[TechGuru]

I really think your motor just got stuck due to corrosion on the commutator which would explain why hitting it with a hammer fixed it. I've had the same thing happen with window motors if they do not get used frequently enough.

 

[john cris]

Well I installed a known good shift module yesterday and still have the problem. Now I can hear a distinct clicking sound coming from the shift module which I didn't hear before. Unfortunately it still gets stuck in 4 low, brakes applied with trans in neutral. Do you think it would be worth while to remove the shift motor and then try shifting it?

Just checked again and now the system seems to be working normally.
System will not shift when in Park.
With trans in neutral and brake pedal depressed:
1) When 4 low switch on dash is pressed the led on the switch begins to blink, then I hear a click from control module after which the 4 low light on the instrument cluster illuminates and the 4 low led on the switch stops blinking and stays lighted. Now it's in 4 low
2) With 4 low engaged if I press the 4 high switch, the instrument panel light for 4 low begins to blink and the shift module clicks and then the 4 high light on the instrument panel lights up. Now it's in 4 high.
3) When the 4 auto switch is engaged the 4 high switch light goes out and returns to 2 wheel drive
4) If brake pedal is not depressed during switching system will not shift
Now I need an off road test to make sure it remains consistent