On my 2002 ford explorer when it shifts from first to 2nd it hesitates and the o/d light flash on my dashboard it just started like 3 days ago what could be the problem?

If the 2002 Ford Explorer is having an issue with the gearbox, otherwise called the transmission, then any of these symptoms may be present. You may notice that the gears slip or slam when they are shifting and that they tend to shift late or early. Basically when You would expect them to they won't, and when they do it won't sound right. There can also be a grinding sound coming from the hood of the car, which is the sound of the gears rubbing on each other. If You leave the car parked for a period of time You might find a puddle of transmission fluid under it, due to a line leak. Finally, the car simply may not drive at all as the transmission has seized up and ruined the car. The OD light is simply the overdrive light, which means the care is running in lower RPMS to save wear and tear. This is meant to be used at high speeds on the highway. Make sure the overdrive is not on when You are driving normally,