I need help with my 4x4

[ER21]

I just bought a 1994 XLT stock and the 4x4 doesn't kick in when i push the buttons. I put the truck in neutral and set the 4x4 button but no response or any lights, i don't seem to find what's wrong. Any advice/help?

 

[Iron Weasel]

First off, make sure you don't have any blown or missing fuses. If you need a diagram I can post one up.

When you push the 4x4 button, do you hear a "click" from the left (drivers side) rear wheel well area? If not, then you need to check the Electronic Shift Control Module (ESCM).

You didn't say if you have a 2 or 4 door, but on the 4 door models if you take off the cover where the jack is, it's in the rear cargo area on the drivers side, the Electronic Shift Control Module is located back there. It's above the rear left wheel well in both 2 and 4 door models though. Anyway, it should have two electrical connectors at the rear of the module. Disconnect those and then push the little white button - you'll need the ignition in the ON position.

- If the LED doesn't illuminate , the Module is dead and must be replaced.
- If the LED comes on and stays on for 30 seconds , there is an error condition and the module will have to be replaced.
- If the module is OK the LED will flash 4 times.

Normally when the first gens won't shift into 4WD, it's one of two problems. Either the shift motor is "lost" or the module craps out. The buttons themselves can also go bad, but it happens far less frequently than the ESCM or the shift motor issues.

If the shift motor were lost, then the lights next to the buttons and on the dash would come on for a second or two, you would hear the ESCM click, then the lights would turn off and you'd hear another click.

 

[DeRocha]

Also check out the 4x4 Troubleshooting guide for more info at the top of the Stock 91-94 explorer forum.

 

[MudRunner90]

if yours does click but not engage, this happened to me try hiting the transfer caes motor, not to hard. it may not have been used for a long time and got gummed up with dirt and what not.

 

[Xeek]

is it possible to push 4x4 when the truck is ON but not running? cuz by myself i just can not hear back there and push at the same time.
from my testing the module does blink 4 times but i cant hear any clicking, no dash light or 4x4 light

 

[Iron Weasel]

Yeah, you can do it with just the ignition on.

 

[Xeek]

i cant hear anything. maybe ill get lucky and the buttons arnt plugged in? anyone have a link to remove that part of the dash, hopefully very easy?

edit: well getting the button assembly out was easy, sadly no easy fix, it was plugged in. now how can i test the buttons themselfs?

 

[DeRocha]

If you still don't have anyone to help you can put your cell phone on video mode and and leave it near the back to pick up any noise.

In my experience the Dash button rarely go out. When then do it is often from someone with a broken shift motor bushing pushing with extreme force thinking if they push harder 4x4 will engage..

 

[Iron Weasel]

Having another person to help you is always a good idea unless you have superhuman hearing.

If that's not an option for whatever reason, I've found that another method is to roll all the windows up, remove the cover where the module is at, shut all the doors / liftgate, turn the radio off and then lean back as far as you can while still being able to reach the button. If you want to take it one step further, find a long stick or something that will reach from the end of your arm to the button and then sit in the cargo area next to the module and tap the 4x4 button with a stick.

To check shift switches:

1) Make this check with the ignition ON.

2) DISCONNECT the "B" and "C" connections to the Sensors, so that their data won't confuse the diagnosis.

3) Now check POWER at the C1 connection at the Module.

4) There should be 5 volts coming from the Shift Control Module to the 4H and 4L switches.

5) Check C1, C2, and C3 for short to ground.

6) Check the Switches themselves by DISCONNECTING C1 and checking CONTINUITY across C1 to C2, and C1 to C3 .

7) If current passes when the switch buttons are PUSHED, the switches are OK.

8) Finally, check for a short between C2 and C3 by bridging between them and activating the 4H and 4L buttons. There are situations where wiring harnesses get crushed in such a way that TWO wires are crushed together and short, even though there is no short to ground.

To check shift motor operation:

1) To check if the Transfer Case Shift Motor is actually functioning (because it may be hard to hear it in a noisy shop) attach a voltmeter to A4 and A5.

2) Have someone activate a shift and look for a brief (one second) increase in voltage, and listen for the relay to click ON, then OFF.

3) If there is power present , then the Control Module is trying to run the Motor. At this point, unbolt the motor and have someone activate a shift again.

4) If the motor doesn't actually turn , it is malfunctioning and must be replaced.

5) If there is no power to the Motor, check both the POWER CIRCUITS again and the SENSORS.

6) If there is incorrect sensor data, the Module won't power the Motor .

 

[Xeek]

diagram is good, my problem is i dont know howto do most of that stuff with a meter or anything.
i need to be told howto check continuity, short fro ground, etc. that i dont understand.

i had someone from work push the button while i listened and nothing. being the module checked itself ok then it has to be the wiring from buttons to module.

 

[DeRocha]

I would try disconnecting the battery for 10 minutes or so.. It will reset all the computers in the Truck and may enable the shift module to start making noise.

 

[Xeek]

i havent done that specificly for 4x4 testing, but ive had the battery unplugged many times before. maybe tomorrow if i take the cargo carpet out and i need to unplug the battery in the process cause my my air tank. the first thing ill try is 4x4 again

 

[Iron Weasel]

diagram is good, my problem is i dont know howto do most of that stuff with a meter or anything.
i need to be told howto check continuity, short fro ground, etc. that i dont understand.

i had someone from work push the button while i listened and nothing. being the module checked itself ok then it has to be the wiring from buttons to module.

Here ya go - several sites that give you a basic rundown of how to use a DMM:

This site.
This site.
And this one too.

 

[richarddews]

I have a '91 4x4 4.0 4dr. Have already replaced auto hubs with rebuilt ones from ebay, and they work great. In this recent cold weather, here is what my 4x4 system has started doing: Pressing 4x4 works great, engages without problems and stays with appropriate indications until 25mph. Almost exactly at 25mph, the 4x4 bottom dash light and little orange led next to the 4x4 switch start flashing erratically. They ultimately both go out at even higher speeds, while flashing briefly on rare occasions. No unlocking or disengaging sounds from drivetrain, through. Once I slow to that magical 25mph, all lights come full on again. What must I check/change? Thanks!