'91 Explorer 4wd relay location
 

I'm having trouble getting my Explorer in 4 high or 4 low. I've been told there's a relay that operates the selector motor. I've had the motor out, tested it, and turned the lug on the transfer case, and gotten it in any range. No binds, but when I push the selector swithc, it flickers, and goes out. I found a relay above the gas pedal, under the dash, but can't verify if it's the right relay. Anyone have any experience in this area? Thanks!

Chris, does this sound right? It is from AllData, for a four-door:
The Electronic Shift Control Module is located at the rear of vehicle, over the left wheel well.

That looks like what I'm looking for! Mine is a 2-door, but I think the control mudule is in the same place! Thanks!

my ford ranger 4wd would not work yesterday and the 4wd
motor died--on the back of the transfer case.
dave

2-door slight difference
 

Chris, the 2-door looks a bit different, but in the same location:

Ken, I got it out, hooked it up, tried to get it into 4wd, the relays pick, and release, but no lights, and no 4wd. I'm not sure if it's the controller, or possibly a wiring problem. I'm gonna try and get a schematic, check voltages, and see what I end up with. Thanks again for your help.

Sorry that wasn't the problem, I have no idea what would be the problem. Let me know if I can help...good luck!
Here's some more "stuff"...

ECM test procedure
The Electronic Control Module (ECM) has a diagnostic capability of its internal circuitry. Self test procedure is as follows:
Remove the Five-Wire Connector and the Eight Wire Connector from the ECM.
Turn ignition switch to the RUN position.
Control Module Self Test
Activate the system self-test by pressing and releasing the self-test switch. Note the results as indicated by the indicator light: NOTE: The self test switch and indicator light are located on the ECM.
A FLASHING Indicator Lamp, (approximately one flash per second) indicates that the ECM is functioning properly.
A STEADY Indicator Light indicates that the ECM is inoperative and must be replaced.
ECM Circuit testing
There are three wiring harnesses connected to the Electronic Control Module (ECM) :
The Eight-Wire Pigtail Harness Connector.
The Five-Wire Harness Connector.
The Eight-Wire Harness Connector.
To check the integrity of these circuits, disconnect the harnesses from the ECM and perform the following checks:

EIGHT-WIRE PIGTAIL HARNESS CONNECTOR
Eight-wire Pigtail Harness Connector (Electronic Shift)
Connect a voltmeter between terminal 8 and ground . The voltmeter should indicate battery voltage at all times.
Connect a voltmeter between terminal 7 and ground , then turn ignition switch to RUN position. The voltmeter should indicate battery voltage. CAUTION: In the following sections where the usage of an ohmmeter is specified, always remember that an ohmmeter should NEVER be connected into a "live" or powered circuit. If the ohmmeter is subjected to a powered circuit, severe damage will be done to the instrument. The vehicle's battery should be disconnected before performing checks on any circuit with an ohmmeter to prevent any accidental damage to the instrument.
Connect an ohmmeter between terminal 6 and ground . The ohmmeter should indicate less than 10 ohms resistance .
Connect an ohmmeter between terminals 4 and 5 . The ohmmeter should indicate less than 10 ohms resistance .
Connect an ohmmeter between terminal 3 and ground . The ohmmeter should indicate 0 ohms .
Connect an ohmmeter between terminal 2 and ground . The ohmmeter should indicate 0 ohms .

FIVE-WIRE PIGTAIL HARNESS CONNECTOR
Fig. 7 Five-wire Pigtail Harness Connector (Electronic Shift)
Connect an ohmmeter between terminals 1 and 2 , then DEPRESS the 4x4 (2H-4H) switch . The ohmmeter should indicate a very "low" resistance value (less than 50 ohms) while the switch is being DEPRESSED.
Connect ohmmeter between terminals 1 and 3 , then DEPRESS the Low Range switch . The ohmmeter should indicate a very "low" resistance value (less than 50 ohms) while the switch is being DEPRESSED.
Connect a test lead between terminals 4 and ground , then turn ignition switch to RUN position and observe the indicator lights. The light in the instrument panel and Low Range Bar should illuminate .
Connect a test lead between terminal 5 and ground , then turn ignition switch to RUN and observe the indicator lights. The lights in the instrument panel and 4x4 Bar should illuminate .

EIGHT-WIRE HARNESS CONNECTOR
Eight-wire Pigtail Harness Connector (Electronic Shift)
Connect an ohmmeter between terminal 1 and ground . On a vehicle equipped with a Manual Transmission (M/T) , DEPRESS the clutch pedal and observe the ohmmeter. The ohmmeter should indicate a "low" resistance (less than 50 ohms) while the clutch pedal is being depressed. If vehicle is equipped with an Automatic Transmission (A/T) , shift the transmission into the "NEUTRAL" position and observe the ohmmeter. The ohmmeter should indicate a "low" resistance (less than 50 ohms) while the transmission selector lever is in the "NEUTRAL" position.
Connect an ohmmeter between terminals 2 and 3 . The ohmmeter should indicate a "low" resistance (200-350 ohms) . This will check the continuity of the speed sensor that is located in the transfer case. The speed sensor picks up the rotating speed of the output shaft from two notches that are cut in opposite sides of the outer ring of the clutch housing assembly.

Checking Ohmmeter Reading For Shift Motor Position Sensor (Electronic Shift) Connect an ohmmeter between terminal 8 and terminals 4, 5, 6 and 7 , respectively. Refer to the illustration for the appropriate ohmmeter readings in each transfer case position.

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Wow! Thanks so much! I printed this info, will try it tonite, and let you know how it turns out. Really appreciate the help!

I have just been through this with my wifes car. I was losing power at a connection above the drivers feet to the module. It needs power to the module for it to work which it sounds like it might be losing. If the motor runs when you hot wire the orange and yellow wires (you can do this at the motor or at the module) then keep swimming upstream till you find it. I have a spare switch and control module if you want to try them. The Explorer forum is a useful site also. Well it's a lot more useful than the generic circuit diagrams in the book and nowhere near as good as the Alldata info you're getting. It sounds like you're close with the relay you first had see if those wires match the terminal 7 and 8 at the module and are getting power. Good hunting.

I performed the first test, and it won't even turn the light on! It's been cold, and I haven't tested further, but, I would like to try your spares. I will check the power between the two terminals, but, I'm sure there is power, if I hook up all the connectors, and hit the reset, it flashes. Let me know how you want to handle the spare thing, I really appreciate the offer! Thanks!

Hi Chris, if you want to pay for shipping I can just send them to you to try. I don't know what your preferred shipping method is. I have a spare switch available now the other switch and module are on e-bay right now. If you want we can send them to you this week and if they sell you could ship them from your place.
Cheers Nick

Nick, I have continuous power at pin 8 on the pigtail, but no key on power at pin 7. I think that may be the problem. Now, to figure out where that wire originates. I may still take you up on your offer, but want to track this down first. Thanks!

Sounds like your after it now. Check that relay and connection above the drivers feet for power. Let me know if I can help further. Mr0077 has provided you a welath of info, we'll get it between us!
Cheers Nick.