4WD lights/1998 Ford Ranger

I have a 1998 Ford Ranger that has four wheel drive. Two different times, the four wheel drive indicator lights have come on when the truck was being operated in 2WD. The lights flashed on and off several times and then turned off for a while and then flashed on, again. The check engine light is not lit during this coded process. The owner’s guide cryptically says soemthing about haiving the truck “serviced” when this happens. The first time that it happened, I took it to a dealer in Southern Cauliflowernia (where I was traveling at the time) who hooked it up to his computer reader and said that it happened because the gas cap wasn’t correctly installed on some previous trip to the gas station. He “reset the computer” and it didn’at flash the secret code any more for a few years. Last week, when my son was driving the truck, the curious message flashed on again. This happened right after he had stopped to refill the gas. He stopped and checked the gas cap and it was properly installed. After he brought it back home and parked it over night the message didn’t reappear any more. My local mechanic thinks that it’s a simple glitch in the little computer board that runs the four wheel drive controls. His recommendation is to “exercise” the 4WD control motor, periodically. My truck has a five speed manual stick shift. The four wheel drive control is operated by a dial on the dashboard that can be set for 2WD, 4WD High and 4WD Low.



Do any of you know what this is about? Can anyone give me a clue what is supposed to be “serviced” when this set of lights flash on and off?



Thanks for any help you can give me.

Try a new gas cap.

Thanks for the tip. I have been told that the flashing 4wd lights are a separate issue from the “check engine” light and that the gas cap should have activated the check engine light, instead of the 4wd lights, if the was the problem. The check engine light did not come on during this last episode.