02 stuck in 4hi

[Torque46]

Hello all,

I took my 02 Explorer on the beach a few times this week and now cant get it to come out of 4wd and back to auto. #17 fuse was blown and I am not sure if the 4wd CM will do this or the trans case shift motor or less likely, the dash switches. The replacement fuse blew when I tried to reselect auto again. I have the 'Factory Service Manual' and it let me through some basic troubleshooting - it seems the dash MSS 4hi button is dead - totally open on the meter.

My OBD2 scanner doesn't log any codes (Acton CP9175). Will the $100 scan tools read the 4WD CM? I read the shift motor rebuild items and the motor has a slight odor of being burnt - I just haven't had enough time to rebuild or replace it yet and don't want to start shotgunning fairly expensive parts at it. I also found out that I can't manually select 2wd with this trans due to the 'auto' mode, so I am driving in wider arcs this week.

Does anyone have a link to good wiring diagrams and not just schematics? Most of the posts and my buddies seem to think the trans case shift motor is the most likely culprit. I do hear a clicking under the seats when I try to select auto or 4lo, but no shifts are made. The dash inidicates 4hi, but the button has no lights for the mode it is in. 4lo will blink when selected, but not actually shift.

Thanks, Chris

 

[Curtis]

I have no idea about wiring, but if you disconnect the 4x4CM you'll get 2wd for now until you figure this out.
Its simply 2 clips.
Drop the glove box by squeezing the sides
Find the module (4"x5"x1") black with 2 wire harnes clips on it. Disconnect both and let them hang

 

[Torque46]

Thanks, I will give that a try. Its raining here for the next few days and I am not exactly eager to lay on my back in a wet driveway while I play with the shift motor.

I actually already had this box changed a few years ago because it wouldn't shift into 4wd - Ford wouldn't cover it under the powertrain warranty because it wasn't 'oil lubricated'. It seems they cover the gears, just not the stuff that controls the gears.

 

[rrgone]

The small motor on the side of the transfer case is what shifts it in and out of 4 low. So unless your stuck in 4 low I doubt it's the problem. Sounds like a wiring issue somewhere - probably the harness to the transfer case is pinched somewhere. Either pull power fuses 17 and 18 or unplug the 2 conectors on the control module like Curtis said.

 

[Torque46]

I pulled the fuses, the CM and even disconnected the battery for 10 minutes and the front axle is still engaged. I thought the solenoid/magnetic clutch would release without power? Anyway, my next step is to chase the wires leading between the engine fuse block and the CM to see if I have any shorts. Does anyone know of a good place to get a wiring diagram?

 

[rrgone]

I pulled the fuses, the CM and even disconnected the battery for 10 minutes and the front axle is still engaged. I thought the solenoid/magnetic clutch would release without power? Anyway, my next step is to chase the wires leading between the engine fuse block and the CM to see if I have any shorts. Does anyone know of a good place to get a wiring diagram?

I thought the electromagnetic clutch would release without power too. Sounds like something is bound up in the t-case. I have never had one apart but read one story somewhere where one of those three steel balls that ride on the apply cam had gotten loose and jammed it up. Unless you are a pretty good mechanic and work on automatic transmissions I think you are gonna have to take it to a tranny shop. Please let us know what you find out. Good luck.

 

[Torque46]

Well I am making some progess now. It seems the clutch solenoid was hanging up a bit, but some gentle tapping on the case with my trusty hammer seems to have corrected the issue. It is firmly back in 2wd or at least not 4hi.

I did find the power input for the 4wd CM on the black connector seems to be shorted right as hits its first transistor/diode on the circuit board. This thing is too tight for me to attempt a resolder, so I am just going to buy a new CM tomorrow. I got a shop price of $150 from the parts place that supplies our vehicle maintenance shop at work, so I am hoping this is the final fix.

Thanks for the help so far. I've picked up a ton of info from this group in just a few days.

 

[rrgone]

Wow, glad that didn't turn out to be a messed up t-case. I wonder which came first, the burned board in the module or the sticking clutch in the t-case? Guess I'm thinking that if the clutch tends to stick it may burn out a new module again. I think I would change out the fluid in the t-case before installing a new module just as a precaution. Good luck.

 

[Torque46]

New fluid is probably a good idea and a fairly easy one now that I have spent so much time with the t-case and the repair manual. After rebuilding the trans last fall due to the 2-3 misshift, I was not looking forward to another major expense. Now I just need to chase down a loose ground in the driver's door and all will be well with the beast.

 

[Curtis]

Well I am making some progess now. It seems the clutch solenoid was hanging up a bit, but some gentle tapping on the case with my trusty hammer seems to have corrected the issue. It is firmly back in 2wd or at least not 4hi.

I did find the power input for the 4wd CM on the black connector seems to be shorted right as hits its first transistor/diode on the circuit board. This thing is too tight for me to attempt a resolder, so I am just going to buy a new CM tomorrow. I got a shop price of $150 from the parts place that supplies our vehicle maintenance shop at work, so I am hoping this is the final fix.

Thanks for the help so far. I've picked up a ton of info from this group in just a few days.

$150 is a damn good price...
glad you found the problem

 

[Torque46]

I got a shop rate via the vendor that supplies our automotive shop at work. They said the list was around $300. I'm putting in fresh fluid tonight.