4wd 4wdlow lights flash 6 times

[Cstoliker]

95 Explorer XLT Manual transmission. The 4wd and 4wdLow lights flash 6 times every couple of minutes. When I first got the truck nothing seamed to happen when the selector was moved from 2wd/4wd/4wd low. I disconnected the battery and now when I put it in 4wd the 4wd light comes on like it should sometimes, other times I need to shut off the truck, select 4wd then start it again for the light to come on. With the light on the 4wd does not seam to be working though. ( I took it off road for a quick test and got stuck rather easily) I can get it in 4wd low occasionally, the indicator lights do not change but the ratio does. Problem is when in low it starts out fine then hear and feel a Bang and it goes back in hi range.

After a short time (real short) the 4wd system is back the way it was before I disconnected the battery. I assume the computer disabled it. From what I have read a bad hall effect speed sensor is the likely cause? If so, there are 2 is there a way to determine which is bad?

 

[joecrna]

Only with expensive code readers. Your 4WD sounds like its going into limp home mode which means the GEM is recieving conflicting sensor data (often not always). This is frequently the Hall effect sensors or the GEM itself. Can't tell without the scanner.

 

[Cstoliker]

Thanks,
Here is another question. Assuming the transfer case is mechanically OK. I was planning to do the brown wire mod anyway. If I did the mode before I get the sensors straitened out would this completely by pass the GEM and give me 4x4 high in case I get into trouble before I get the sensors fixed?

 

[joecrna]

No, the BWM completly eliminates 4WD under all circumstances regardless of the dash switch position. Power will only go to the rear wheels.

 

[Cstoliker]

Hmm.. I thought the BWM engaged 4wd making it 4x4 instead of 4wd auto or disengaged 4wd so you can get 2wdlow.

I brought the truck to a local garage and they plugged in a code read and got "no codes present", I think this was an OBD II code reader and to my understanding tranfer case problems are not stored in the OBD II computer. Is it just a dealer that can get the codes?

 

[joecrna]

Yes, its a completly different code reader. You also need a tech that knows how to properly use one, many do not. Reread the BWM thread to understand what it will do for you. When the brown wire is interupted (switch flipped) the ball ramp electromagnetic clutch in the TC will not function. The front output shaft is never engaged under any circumstances.

 

[sport'96]

same problem

my 96 sport did the same thing, only 4wd wouldnt engage at all and got stuck in the field. took it to a local ford dealer and they checked the axle over from end to end and the transfer case. then they plugged it into a code reader (not OBD II) and found that the switch had been unhooked. that fixed it and it works great now.

 

[Cstoliker]

Yea on the 97-01 models the BWM disengages the front axle giving the option for 2wd. On my 95 (witch comes with 2wd) it is designed to not only disengage but also.

"bypass all the GEM-controlled electronics and, using a simple switch, apply power directly to the transfer case clutch coil, again via the brown wire."

Making it true 4x4 instead of control track (torque on demand) 4wd auto. So I believe it should work for me even though the 4wd system is disabled as long as the selector switch still activates the CAD and locks the front half shaft when the selector is set to 4wdauto. (which I believe it does)

 

[Cstoliker]

I did the BWM today. I used a lighted switch and the first thing I noticed was the switch lighted dimly when 4wdAuto was selected and bright when the back wheels spin as it is supposed to. But neither with the switch on or 4wdAuto selected did the front wheels engage.
I jacked the back end of the truck so the rear tires were off the ground, put it in gear while in 2wd the front drive shaft spins. I assume this is because of friction inside the transfer case. In 4wd the front drive shaft still spins so the CAD must not be functioning or the front wheels should have pulled the truck off the jack.

So now the question is, would a problem with the CAD trigger the indicator lights to blink 6 times or does the GEM disable the 4wd by disabling the CAD. In other words is the CAD the problem or the result of another problem?

 

[joecrna]

Wow, we're deep into the electronics now. I don't have an exact answer for you but your train of thought has been spot on thus far. The GEM gets info from several redundant sources and it wouldn't be unusual that it could control the CAD as well as the TCCC. If you jack up both ends of the truck, do the front wheels spin or just the front drive shaft?

The friction inside the TC with the electromagnetic clutch coil disengaged is minor. If the front wheels spin in the air, the CAD is working. When lowered, if the fronts stop, its just internal friction. If when in the air, the front wheels don't spin and the front drive shaft does, then the CAD is not engaging.

The 6 blinks are not a specific code. Its just the "alarm" to tell you there is some code stored for the TC. The 4WD does however go into a limp home mode, disengaging the front wheel drive so the drive train doesn't bind and cause mechanical damage. I learn towards a bad GEM, but its a $350 guess (thats what my local dealer charges for a GENM). When I got to this kind of point with the electronics in mine,I paid the dealer for the diagnostics.

I may be the best of two bad options.

 

[gijoecam]

Ultimately it's the GEM that controls both the t-case and the CAD. Unfortunately, it's not an easy thing to rig up manual control of the CAD, although it is, in fact, possible.

Now, as for the problem, as already mentioned, withot knowing what the GEM is seeing for inputs and outputs, there's no way to tell for sure, but I like to start with the simple stuff I can check. In this case, start at the switch, and check the resistances through the switch using a digital multimeter. If the GEM never gets the signal to go to 4auto, it won't even try.

Could also be the fuses... don't have the schematics for a 96 in front of me, but that could do it, for sure.

Could also be the afore-mentioned sensor on the CAD. If it never sees the CAD engage, it'll never lock the t-case. In your case, the CAD obviously isn't locking, otherwise, the BWM switch set to send power down the pipe would cause the 4wd to engage.

-Joe

 

[Cstoliker]

Thanks everyone
The CAD is not engaging as the front driveshaft spins while the front wheel are on the ground. I believe the GEM is actually working because of the lighted switch I used for the BWM seams to indicate power being sent to the TCCC normally (with the switch off) This would also rule out a switch or fuse problem.

I guess the bottom line is I need to get the codes read. I would rather avoid dealers.(Dealers are more likely to tell me my head light fluid is low or muffler bearings are seized.) Can someone tell me what is needed to read 4wd codes? I'll call some local garadges but I need to know what kind of equipment I'll need to ask if they have. (obviously the codes are not stored as part of the OBD II system)

 

[joecrna]

They are referred to as NGS or WDS scanners. My understanding is that they, or at least their software are manufacturer specific. They cost several thousand dollars and are thus prohibitively expensive for all but dealers. I've also been told that finding someone that can interpret the data they provide isn't a simple task either. Don't know how true this is, but its something worth considering.

Apparently you get info like "lack of continuity in ABS circuit" and need to know how this impacts the GEM and thus where to look for a faulty part in the 4WD system. Doesn't seem too hard to me but I am just relaying what I've been told.

 

[BigBlackMerk]

a friend of mine has a 97 x and all he did to make it 2wd was pull out the fuse for the 4wd. at lease thats what he told me. is that posible? and so what fuse # is it

 

[antitheone]

hello

you guys seem to be really helpful and i have a similar situation could you check it out for me?

http://www.explorerforum.com/forums/showthread.php?p=2321242#post2321242