I get the 4wd/4wdLo light flashing like other explorer owners, but mine start to flash above 35 MPH. They start flashing and then stop. But the lights (4wd & 4wdLo) stay off. I've done what other users have suggested on other postings, cycling the 4Wd Auto and 4Wd Lo switch after turning off/on the car. After I turn it on, if I engage the 4Wd Auto the light is on and working properly, until I go over 35 MPH, then it starts again.
But one thing that I have noticed is that when I'm in 4Wd Auto and turn full lock (like in a parking lot manuever) the wheels feel as they where dragging fully engaged in 4Wd. Isn't the system supposed to engage the front axle when it detects that the rear wheels are slipping?
Based on the posting of other Explorer owners, would this mean the following:
1.- That the rear transfer case HALL speed sensor is faulty, due to the fact (I imagine) that the front axle is engaged when in 4Wd Auto all the time. It does not matter if the 4Wd / 4Wd Lo lights are blinking or not, the front axle feels engaged, and drags in slow turns (almost full lock turns).
2.- Does the 4Wd system default to fully engaged 4wd in the event of a HALL sensor failure? If so, this would explain the dragging while steering at slow speeds.
3.- What are the probable effects or causes of the 4wd/4wdLo light coming on at speeds above 35 MPH?
4.- After engaging the 4wd Auto, it does not matter if the 4Wd light is on normally, or if it's blinking, the front axle feels engaged all the time.
Any help with all these questions would be greatly appreciated.
Thanks in advance to all.
Sincerely,
Art Toscano

 

Hello people, I would appreciate your help on this issue. Aren't we supposed to help each other with our experiences?
Please, help, before I commit truck hara-kiri!
Thanks in advance to all who answer!
Sincerely,
Art

 

Since it appears that you are able to somewhat get it to go into and out of 4WD that would eliminate a faulty shift solenoid. My initial suspicions is that it is a faulty speed sensor. I have heard that the '95 & '96 Explorers default to locking the front and rear together when something fails. On the '97 and up though it disables the system and defaults to 2WD mode. I have also read that on all '95-'01 Explorers with Control Trac, the system goes into 2WD at 35 MPH. It is interesting that you are having your problems at 35 MPH. Without reading the fault codes everything will be a guess. Here are two more guesses though. Since it happens at 35 MPH, it could be the computer not being able to take it out of Auto mode or it could also be the shift solenoid failing to take it out of Auto. The speed sensors, shift solenoid and GEM (General Electronics Module) are easy enough for a "do-it-yourselfer" to replace. Unfortunately you could waste a lot of money trying to find the right part without checking the codes first. A final though is how is your transfer case fluid (full and clean)?

 

 

Thanks for your response and excuse my delay in responding to your questions. I had the transfer case oil checked at the dealer aproximately a year and a half, and was told that it was in good condition and did not need to be replaced. I'm thinking of taking the Explorer over to Autozone and see if they can read any service codes from the computers memory that would point to a failure in the speed sensors. I cleared the computer memory (disconnected the battery for about 15 minutes) and got both lights to blink again after 35 MPH. After turning the Explorer off and on (after selecting 2Wd), the lights where off and I was driving normally with no light blinking on and off. The lights (4Wd and 4WdLo) blink after going over 35 Mph and don't come on while I'm driving normally in 2Wd.
Do you know how to test the speed sensors (rear in particular) or know where I can download info on this off the internet?
I think the rear sensor might have a problem, since I believe it's the one that enables the 4Wd and activates the front axle.
Thanks again for your response and I promise I'll get back to you sooner.
Sincerely,
Art

 

Per my '97 Service Guide the transfer case fluid should be changed every 30K miles. I would have it done, regardless of how good it looks. It is easier to change the transfer case fluid than it is to do an oil change provided you have a pump to pump the new fluid back in the fill hole on the side of the transfer case. Since you don't get the error when in 2WD, then it almost certainly points to a faulty speed sensor. It could be either one though since the GEM monitors both the front and rear driveshaft speed sensors to watch for differences in speeds. If the rear seems to be turning faster than the front the GEM will divert power to the front, figuring that the rear tires are slipping. It will increase the power to the front until either both speed sensors detect the same speed or all of the power that it is able to divert has been directed to the front. If that happens, but the rear still seems to be turning faster than the front, the GEM figures that this is an impossible situation and will flash your 4x4/Low lights to warn you of a problem. A failure of either speed sensor can cause this problem. Autozone will not be able to read your codes if all they use is the OBD-II scanners that they sell. The GEM doesn't provide codes via the OBD-II data port. It will take a Ford NGS Star tester or equivalent to extract the codes. The flashing does symbolize a code though but I don't have a source to decipher them. I don't know of any procedure to test the speed sensors either. They are just a hall-effect sensor that detects the metal gears inside the transfer case going by.