I recently bought a 91 explorerXL. When we first got it we noticed the 4x4 wouldn't work. We bought a manual and found out the Electronis control shift module was missing. Anyway bought one of them and installed it and no 4 wheel drive. We thought it might have been the 4x4 switch on the dash since it wouldn't light up. Bought one of them and 4 wheel drive still doesn't work. Changed the fuse in the power distributation box. Still no 4 wheel drive and switch on dash still doesn't light up. HELP! momto5

 

Many places talk about cleaning the shift motor. It's commonly needed on these, especially when the shift motor isn't used very often.

 

Does anyone know if the test described at the top of this article is accurate? If so I think I know what's wrong.

I was having some trouble with my 1991 Ford Explorer transfer case and talked with a service tech up hear in Alaska about it. He told me about a test you can perform to the processor board that is located in the rear left access panel next to the jack and rear windshield washer container. In has 2- wire harness pin connectors attached to it on the left side. If you remove the 2- wire harness pin connectors and turn on your ignition switch. Now you can push the white square button on the bottom edge of the processor board and it will turn on a red LED right next to the button. If the red light flashes this means you have a problem with your actuator motor assembly. If the red light stays bright this means you have a problem with the processor board. I found a problem with a the actuator motor assembly. I followed the instruction from your web page on Transfer case problems. I found it helpful but would like to add some info to it. I didn't need to remove the harmonic balancer nor drain the fluid. The 4 bolts that hold the actuator to the case were removed, the magnetic pickup sensor and I cut the one brown wire going into the case. I opened up the actuator and removed the armature. Cleaned it up with some 400 grit carborundom paper and washed it down with some CRC contact cleaner. I pull the brush holder springs out and put a little more tension on them because they seemed to only apply a little tension to the brushes that were worn to a length of about 1/4". I polished up the armature shaft where it comes in contact with the bronze oil impregnated bushing with the 400 grit carborundom paper. I install some graphite grease on the worm drive shaft and gear and bushing surfaces. I installed some RTV sealant on the cork gaskets before assembling. I removed the 3 -8/32 X1/2 " anti-theft screws on the gear cover and cleaned the face of the gear with the foil trace circuits on it and the 5 copper contact surfaces on the cover with CRC contact cleaner and 400 grit paper. I used some RTV sealant on the cork gasket before installing the cover. I also installed some RTV sealant on the 5 wires that go through the cover rubber grommets that don't do a good job at keeping out the fine dust that was found on the contact surfaces within. This I feel is the root of the problem! Now I cleaned up the transfer case and actuator surface where it meets the case and installed some ATV sealant on it and bolted it back together. I install a #14-16 pin connector male and female on the wire I cut and put some heat shrink tubing over it to seal it up. After 1 hour of tinkering I am back on the road. Wala- a simple push of the button and I was in 4 wheel drive again. The first snowfall in Alaska this year has now come and I am ready for it. With 4 studded tires I can drive on the glacier roads at 55MPH and feel safe.



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Thanks. I'm looking forwaed to your answers.momto5

 

Well, I seen that white square-shaped button on the bottom of the processor board. I have no problems with four wheel drive engagement, but this LED now lights up permanently -- just all the time ignition is in the ON position.

But ALLDATA says that normally this LED shouldn't light. I have been pretty confused upon discovering this fact, but the system works just fine so I don't bother myself with this LED.

But I must conclude that the procedure that guy from Alaska described could be not 100% accurate. Though there is direct connection between this LED and 4WD engagement ability.

With best regards,
Yuri,
Moscow, Russia

 

Thanks Yuri, I've had some missgivings about the validity of this test. For one thing I don't have a plug back there that has only two wires on it. katieangelamber

 

No problem, glad to help you!

About lost connector, it seems you have power connection terminal missing.

As I remember (I fixed my 4WD some time ago), the processor board has three terminals: A, B, and C.

One, the most large connector is for communicating T-Case shift motor and its position sensor.

Another (6 or 7 pins maybe, don't remember for sure) operates dash buttons and indicator lights.

And the third, the lesser terminal is the power supply for the processor board. It seems that you have this one missing.

With best regards,
Yuri

 

Hi Yuri. I have all 3 plugs plugged in. It's just that none of the plugs has 2 wires. The test said to us the plug that has 2 wires. None of my plugs has 2 wires. All the plugs have more than 2 wires. momto5

 

I have a 1989 Bronco that does not have the 2-wire plug that is commonly mentioned. To test the transfer case shift control module disconnect the two wire harnesses at the bottom of the module one has 5 wires the other has 8 wires. (There are 7 wires molded into the top of the module that cannot be removed) Next, turn the ignition to the run position, push the white button, a flashing red light (1/sec) indicates the module is functioning properly, a steady light means the module is inoperative and needs to be replaced.

 

alright, lets back up here. First of all, the controller self test simply tells you if the controller is working or not. If the LED flashes it indicates that the control module is functioning properly. If it is steady the control module malfunctioned.

Second, if you remove the shift motor, you can disassemble the pin with the speed sensor by removing the red piece in the connector and pulling the wire out. This is much better than cutting it and splicing.

The shift motor rebuild fixes many problems. The part that is most important is replacing the rubber washer that goes around the stop underneath the cover of the motor. This rubber deteriorates over time and breaks up causing the control module to not know what the t-case is in (4hi, 4lo, etc).

I rebuilt my shift motor once but the screws holding the cover on snapped so I had to RTV/glue the cover back on. This held for a month or so but it ended up coming loose again. My local Napa had a reman motor for $80 or so with a 1 year warranty or a new one with a lifetime for $130. Its not worth screwing around with the stock motor when you can just buy a new or reman for that cheap. I never have to worry about my shift motor again since I put the reman on there.

I can provide the Ford diagnostic procedure for troubleshooting the 4x4 system if you guys would like. It takes a multi-meter and some time but is the best way to narrow down the problem.

 

Man.............I have to say this is the best thread to answer probably hundreds/thousands of posts in this forum. I have had the same issue and have tried many differnent searches in the forum to find "I used 4 wheel in dash light"
Is there a main topic board that this post can be on so the multitudes can get an answer without doing mass searches.

For my problem I needed a quick fix. I installed "WARN" manual hubs just to keep in 2 wheel drive so I could get to work. It was slipping into 4W drive as I drove down the road. I will use some of this thread to fix when I get time.