97 Explorer 4 Wheel Drive dash lights flashing

[barmfield]

Hi All,
I am from Oregon and need some help. I have a 97 Ford Explorer, 4.0 lt engine, with 125,000 miles, with automatic 4WD.The 4WD and 4WDL dash lights keep flashing and my 4WD kicks on intermitantly for no reason. The dealer wants $770 to replace the "speed control motor, a wireing harness located by the transfer case (I think) and 2 wheel speed sensors". I want to do the work myself, but I am unsure of where these items are located on my vehicle, where to buy them, and if this is something I should tackle myself. Anyone have any experience with this stuff? Any suggestions?

 

[joe doe]

the reason it costs so much is because the wheel speed sensors are integrated into the front hubs .you have to buy the whole hub to get them.....at the dealer very expensive ..about 280.00 if i remember right ..each side ...i got one at autozone for 175.00.......you can check these yourself with a ohms meter .....find the leads coming off the front hubs and probe them with a ohms meter....if they are good they should read somewhere between 300-400 ohms ...the higher near 400 the better....check the threads here someone has the exact numbers ..but my new one read around 399 sooo...........not sure on the transfer case thing

 

[joe doe]

wait ,wait ,wait ...i know on my 2000 ex the speed control motor and abs sensor are the same thing ...its located in the rear axle.....cost me under 25.00 bucks at the dealer .i just replaced mine because my abs light was on all the time .same sensor though does both jobs i believe.read up on it

 

[ñòóKýçrÕôK]

Buy a Haynes or Chilton manual. They'll tell you exactly where every part on your vehicle is and how to check and replace them. I've used them for years.

 

[NHale623]

Unfortunately, the Haynes/Chilton manuals offer very little for the 4 wheel drive systems on these trucks. They don't even mention the speed sensors in the transfer case.

barmfield, the speed control motor and wheel speed sensors in your front hubs and rear differential have nothing to do with your transfer case. The shift motor on the transfer case is only for hi-lo range selection. There are two sensors for the front and rear driveshafts, they are on the back of the transfer case.

My suggestion would be to unplug the wiring harness located on the top of your shift motor, mounted on the back of the transfer case. Clean the connections well, plug it back in and see what happens. That connector is not only for the shift motor, but it also contains the connections for the two speed sensors.

If that doesn't fix the problem, remove the two sensors from the transfer case, clean and reinstall them. The sensor for the front driveshaft is behind the shift motor, so you'll have to remove it to gain access to that sensor. You don't have to drain the fluid from the transfer case, but you might drain and refill it while you're under the truck.

 

[barmfield]

Thanks NHale623 and Everyone else

Some very helpful advice here! I am really grateful.

 

[gijoecam]

I'd mirror all of what NHale said and add a couple things.

Indeed, start with the connector and some contact cleaner, looking for fuzzy green connections; a clear sign of water infiltration. When you reassemble it, be sure and use some dielectric grease to help seal out the elements.

It sounds to me like the mechanic is throwing parts at it without accurately diagnosing it. The flashing lights are an indication that the GEM has detected a problem with the system. Any mechanic worth his salt should be able to connect and read the GEM DTCs (AutoZone's scanner isn't capable of reading the GEM). That trouble code should pinpoint the problem right there. At the very least, he should be able to explain, in detail, what led him to the conclusion that you need all those parts replaced. (example: He did X, Y, and Z, and tested R, S, T, and V, and because this worked and that didn't, this thingy over here is bad) It doesn't sound like that's the case.

As they already mentioned, on a 97, both front and rear shaft speed sensors are mounted on the t-case. In 98 they did away with the rear sensor in favor of utilizing the rear axle speed sensor instead. (Guess it doesn't make sense to have two separate sensors monitoring the same thing) However on your 98, you still have both sensors on the t-case.

The front wheel speed sensors (if that's what he was referring to) are only tied into the ABS system.

Now, by 'the 4wd kicks in intermittently for no reason' do you mean that the 4high light comes on without turning the switch on, or do you mean that the automatic 4wd engages the front axle when making parking lot maneuvers or low speed turns, etc? It might help us decide where to focus our efforts.

Let us know and we'll see what we can do!

-Joe

 

[wynlee1]

my 4 wheel drive kicks on while Im driving down the road, and the car pulls to the right and makes this grinding noise, and the 4 wheel drive lights flash. somebody please help me!!

 

[drdoom]

1. Do all four of your tires match EXACTLY?

2. Try cleaning the OUTPUT sensors in the transfer case. One is hidden behind the shift motor, the other is more visible, up where the rear driveshaft connects. These are secured by a 10mm bolt. These are Hall Effect switches, so there are magnetic, and are known to pick up metallic sludge which can throw the readings off. Pull them out CAREFULLY...work them out, lubing & twisting a few degrees. Then clean them, and re-install.

Look at this photo, the sensors can be seen on the harness:

Here is another photo, showing the VSS (the speedometer). However, the rear OUTPUT sensor can be seen right below the driveshaft, directly above the fill plug.