98 4WD kicks in when turning at low speed

[shogun]

1998 AWD Mountaineer Problem where the front wheels go into 4WD when turning corners on the road or into parking spaces, Auto Hi is selected. 63,000 miles on odo, transfer case fluid is fresh and full. This started happening within the last 6 months, wife noticed it after new tires were installed, (may be believed or not). Anyway, it as if the sensor(s) are reporting that the front tire(s) are spinning too fast and sending drive to the front end. Happens when turning left or right. Any thoughts on this? Thanks.

 

[Jason_25]

Then your mountaineer is 4x4, not AWD. There is a big difference.

Do you ever notice the 4x4 lights flashing?

Does it work fine in 4high and 4low?

Are the tire pressures equal?

 

[shogun]

Hey Jason, it's AWD, I'm no SUVer, it's her truck, but it's got a rotary selection switch with Auto, High 4 and Low 4. Yes, I put all the pressures to 33 psi, I had them at 35/30 per the factory, no change. 4 Hi and low both work. The problem is identical to turning sharp on pavement in 4 High, the front end binds up.

 

[Jason_25]

What I would do then is go to your local Ford dealer and ask them if there are any TSB's on your model year truck on the front end binding up. Or alternatively, you could search the net for them. If you want to see them in full though, you will need to pay www.alldata.com.

There are two possibilites here.
1.One or more of your transfer case speed sensors have failed or are failing
2.The GEM needs reprogramming

The TSB's will tell you if the GEM needs reprogramming. If there are no TSB's on your truck for the GEM then I would go and replace the transfer case speed sensors.

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Ok School Time:
Your Mountaineer is not, in fact, AWD. AWD is only available with V8 explorers. AWD means that both axles are getting power all the time. 4x4 means that the front axle only gets power when you select 4x4 or the GEM determines that your rear wheels are slipping. Thus, the "Auto4x4" mode that you are having trouble with.

 

[shogun]

Jason - Gotcha! Hmmm, or not. In Auto mode I thought that the fronts were getting mimimally 5% of the drive up to 35mph, or at least that's what I read. Oh well, at least I know it's got a problem. I'm much more familiar with C5 Vettes. : )

 

[TPLYNCH]

Shogun, you are correct about the power to fronts up to 35MPH. But because the system goes to 0, it is not AWD since the fronts are not powered at all times. That's also why the Explorer is considered a Part-time 4x4 system.

As for your problem, you can try cleaning the speed sensors on the t/f case. They are little magnets. I believe they can be pulled out of the case. You can run a search. If the problem is not the sensors, then the GEM is most likely the culprit.

 

[dogfriend]

replace driveshaft sensors?

I had to remove and replace one because it was leaking where it goes into the t-case. Not too difficult, but you have to remove the shift motor from the t-case to get to one of them. You have to remove the electrical connections from the shift motor connector shell which was tricky. Dead Link Removed

The part cost about $32 for one (there are 2). It is a Hall-effect sensor which means that it translates a changing magnetic field into a changing electrical signal which is interpreted by the computer as a driveshaft speed.

I would try to verify that all of the wiring and connectors look ok before replacing the sensor because the sensor itself is a pretty basic design with not much to go wrong. If you decide to replace it, be sure to call it the driveshaft speed sensor, not the vehicle speed sensor because that is different and you will confuse the parts guy to no end.

 

[Buds007]

I had the exact same problem you described. All I did was a TT and Shackles/aal. It took the problem away, and made the suspension much tighter, more like a truck. Now the back is softer. But RS9000s will fix that.