1999 Navigator Control Trac AWD

[pokeeto2]

:shifty: You know that Automatic A4WD thing Ford put on the Expeditions, & Navigators in 1999. On 4WD's, from 1999 & up they replaced the 2WD selection with A4WD.

My 1999 navigagator, for some reason when I take off from any stop and up to 35 MPH the Automatic A4WD always kicks in, even when the tires don't slip and in normal driving. I know it's that cuz when I put it on 4WD Hi & 4WD Low, it doesn't do it. I have had other 99 and a 2000 Expedition, I never had this issue.

Anyone Know????????????
Though, the truck does have a slightly smaller tire size. the truck was supposed to use 255/75SR17. And it has a set of 255/70SR17. Can this be the cause?????????

 

[2001LS8Sport]

It sounds to me like you have a speed sensor in the transfer case that's bad. It thinks you're spinning a tire.

 

[pokeeto2]

It Makes sence, Is this the only part on the truck called a speed sensor, I see a good price from Napa.

 

[2001LS8Sport]

It Makes sence, Is this the only part on the truck called a speed sensor, I see a good price from Napa.

No! It has sensors for the ABS, and the VSS (vehicle speed sensor) too. Now, it's possible they double up the use of one sensor, so some homework would be in order. This isn't an uncommon problem and a trip to the dealer might not hurt if you don't have the diagnostic tools needed to check the sensor outputs. Might save you money in the long run. It could be something like a module instead. A good diagnosis will tell you for sure. But I'm betting on the sensor.

 

[pokeeto2]

I guess thats what I might do, Only the dealer diagnostics test, I'm comfortable changing these this myself.