Re: 1998 expedition 4wd switch NG
It's most likely a bad TCCM, or transfer case control module. It's utterly the 'electric motor' that switches the transfer case modes on your behalf. It's located under the dash between the driver and passenger footwells. You'd be best by searching local salvage yards for a replacement as getting a new unit from the dealer will be three times the price, and a used unit can last longer, or just as long as a new unit: RockAuto Auto Parts
This is the only drawback to electronic transfer cases, is the TCCM.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!