4x4 module may be bad

[IZwack]

Well be sure to drop by your mechanic and give him some ice cream -- nothing like ice cream to brighten one's arduous day

 

[gadge]

Actually I brought them all frenchy baked goods.

 

[IZwack]

Oh fantastic -- I like your taste in pastry

 

[fled]

thank you for the post was very usefull. now i know what to look for ... hope its rear sensor on the transfer case motor so that will be my first fix try.

 

[ExpoGirl]

My problem is cured!

Well, I had my Explorer to the mechanic a week or so ago, and they tested it, but were unsure yet whether it was the 4WD Module or the 4WD motor. As the computer wasn't able to communicate with the whole thing. So, we tried the Module...and guess what...it is working great!!!!!!!!!:exp:

 

[mac999993]

Questions:

My 4x4 is not working.... No lights when I press 4x4Lo, 4x4hi or 4x4Auto... no noises from the xfer case... nothing ( soi I presume the signal is not commanding either the clutch solinoid to engage or the swith motor to move). I discovered through another thread that it is possible that my 4x4 Control Module is failed... (02 Explorer 4x4 CM's can fail from disconnecting the battery (Beleive that!? It's TRUE! See this thread : http://www.explorerforum.com/forums/showthread.php?p=1993131&posted=1#post1993131 ).

1) Anyway... I'd like to confirm that it is the CM that is bad.. How can I troubleshoot this?

2) Also, is it possible for 4x4 to be on if there is a failed CM... ie. could 4x4 be engaged due to a failed CM? I have front end vibrations and the 4x4 doesn't work, that's why I'm suspicious.. Any help would be greatly appreciated..

 

[tkmondy]

I have a 02 Explorer 4.6L with A4WD. I had a problem where my 4X4 Hi/Lo can't remember light was flashing intermittently, when cold. Ultimately a week or so later my transmission disengaged at a stop sign and I had to have it towed. I noticed that my speedometer would still register even though the transmission wasn't engaged. So I went straight for the Shift motor. You should be able to hear the motor spin with the Key-ON Engine Off, transmission in neutral and your foot on the break while alternately pressing the 4x4 HI and 4x4 Low buttons with the window open and radio off.
The shifter motor can easily be tested by removing it from the transfer case, locating the power pins and applying a voltage (12VDC) across the pins (the polarity of the applied voltage determines the direction the motor spins). Be advised that the 2 connectors at the 4X4 control module should be disconnected as a precaution and avoid touching any other pins as you might damage a sensor.
I wasn't able locate my problem, after reassembly the problem went away. But here is what I do know. The Dash panel lamps are illuminated under control of the PCM. What this means is the Lamp function is decoupled from the 4X4 Dash mode switches. On a properly functioning unit the Lamps illuminate only after the transaxle is fully engaged in the selected mode. That being said, the Shift motor has a gear encoder switch that reports the position of the transfer case gear cam. Mine just happened to have stopped in the (dealer installed option) neutral position which I don't have. I removed the grear encoder switch and Ohm'ed it out, not really knowing exactly what to expect. I spun it several times, the 4 internal switches all opened and closed but I don't know if there is a particular sequence to look foe (i.e. binary encoding). So back to the flashing Dash lights, it is the gear encoder that signals the 4X4 control module the state of the transfer case. So the problem has to be this gear encoder or the 4X4 control module, or a connection problem. Remember, the gear encoder is that sealed gray colored disk with 5 wires mounted to the shift motor and the connector from the 4X4 controller is exposed to the weather. The most likely culprit is the connector connection. To test the motor don't worry about disconnecting the sensors and all, just support the motor so as to releave the strain on the wires. If you can switch between auto and 4X4 High that is a good sign that your 4X4 control module is at least partially working, I would suspect a fues, the motor or the connector first. Also the shift motor gets it power directly from the 4X4 control module, this is due to the fact that it is a directional motor, these motors represent a significant load to the 4X4 control module. Just the motor drive circuit could be bad, which could be due to attemping driving a bad motor. So test the motor before replacing the 4X4 control module so that you don't blow the new one when you install it.

 

[rtrhea]

I have a 2002 XLT with Automatic 4WD. I bought it used and the 4WD lights on the dash do not come on. (the 4WD doesn't engage either). So I started searching the forums and asking mechanics at the dealership what they thought about it - and most things lead to the Shift Motor. I tried tapping it, taking it off, inspecting it for damage, put it back on, still doesn't work. Two days after doing this is I was driving down the road and heard the shift motor revving up intermittently. My speedometer changed, but my engine was running fine with no RPM change or anything weird like that. Talked to some mechanics again and they said to disconnect my battery because the computer gets weird sometimes and needs reset. I did that and it drove perfectly fine for at least 200 miles.

However, I drove it yesterday and heard the high-rpm-revving sound coming from the Shift Motor again. But when I got back in the car after eating lunch it wouldn't go in reverse!!! I pushed it back and drove away. My next trouble was in the Home Depot parking lot when I put the car in park and noticed it rolling across the parking lot as I walked inside!!! Lastly, I drove the car home and parked it in the driveway and found out later in the afternoon that Forward wouldn't work either. Now it won't engage the transmission for any gear. Help!!