Re: 98 Mazda b4000/is it a ford ranger
does it have vacuum hubs? if it does the outer hub will be plastic and you will find a vacuum line going to the inner hub. When resetting the computer (flashing 4wd light) unhook the negative battery terminal only, leave it off for 30 seconds and reattach, this will reset everything. vehicle may run rough for a short period of time until the computer readjusts to the vehicle. Unhooking the positive terminal before unhooking the negative terminal can fry the computer. No need to unhook positive terminal to reset. you also have a small electric motor on the back of the transfer case that engages your 4wd, check the electric terminals at this motor for corrosion partial broken wire etc. sounds like your problem could be in this area. I dont think this unit costs over $200 if it has to be replaced. If the problem was at the hubs, light would show 4wd engaged. Hope this helps. Oh not exactly a Ranger, but same running gears as far as I know.