I have a 99 expedition. The issue that I am having trouble with is that the 4x4 and low range light is on but the vehicle is not in 4x4. Also the speedometer will only register going 20 mph even thought the vehicle is traveling fast then that. Any help would be great thanks.

 

Where you stopped and in neutral when you shifted into 4WD low?

 

Nope. The vehicle hasnt been in 4 high or 4 low in years.

 

I guess I assumed you tried going in and out of 4low just to see if the light would reset.

 

No your correct. I did try that. I also drove it in reverse for 100 yrds. I know with some 4x4 the transfer case would show 4 high and won't unlock unless you reverese for a few feet. But this one the dash shows its locked in and the speedomoter is acting like it is but the vehicle drive normal.

 

Inspect the electrical wiring going to the shift motor on the back of the transfer case. It's possible the wiring harness got snagged and was damaged. It's the contacts down in the shift motor that control the 4WD related lights on the dash.

 

The 4x4 Low Range dash light on, and the symptom of the vehicle NOT being in 4x4, driving "fine", but the speedometer working incorrectly (reading much lower (at approx 1/3 to 1/4 actual speed) is typically caused by the Transfer Case Motor's external controller failing. They seem to fail commonly, and the most common cause is moisture penetrates the supposedly "sealed" electronics in that controller. Replacement is more of a hassle than it should be because Ford went "cheap" on the transfer case portion of the wire harness and the harness in IMHO has one to few connectors that would make the job relatively easy. Instead, you unplug one connector, but the other connector is a "shared" connector. So you have to unplug the second connector, take a picture to "memorize all pin locations", release the red lock-piece that holds the connector together, and replace the individual pins that go to the Transfer case shift motor. (U--tube has some videos). Most autoparts stores stock replacements (or you can get it for much less from rockauto.com). Replacement can be done at home on flat ground by shimmying under your vehicle. I assume you have fixed yours, or sold the vehicle by now, so I am posting for other readers with the same question. Access is challenging, but patience prevails.

The symptoms are caused because when the motor controller fails, it often reports the wrong "state" to the GEM and instrument cluster, reporting that the vehicle is on 4x4 Low range mode, when it is not. That lights the dash light. However, it ALSO changes the multiply/divide formula used by the electronic speedometer in the '97-2002 F150 (and Expy). Because when in "actual 4x4 Low range (vs. the electronics malfunction)" the transmission output shaft revolutions to wheel revolutions are lower (a different Low Range ratio, for high climb power) so, the speedometer calculates speed differently for each output shaft revolution. When the truck is ACTUALLY NOT in 4x4 mode (but thinks it is because of the shift motor controller malfunction and short), the speedometer uses the Low Range ratio when you are NOT in low range, and so the speed is misreported by the difference in the Regular range and the Low Range ratio. (That is somewhere between 3-4 times difference, so the speed reads about 1/3 to 1/4 the actual speed.)