My son has a 1999 Ford Ranger Single Cab Long Bed. He got in his truck the other day and when the truck shifted into second gear it jerked and the overdrive light began flashing, Fluid looks good and doesnt smell burnt, While applying the brake you can shift through all the gears and there is no noises at all. What could cause this to happen? Please help??

 

Use the search button for the term "valve body gasket" . That seems to be a common issue.

 

My '99 ranger short bed does the same thing...at least similar. It doesn't want to shift into 3rd without letting off the gas. When I let off the gas for a second it will shift up. Then seemingly at random times while driving the O/D light will begin flashing. When that happens it does not downshift when coming to a stop. To accelerate from a stop I need to shift down manually to 2nd. The O/D shifting problem goes away if I simply restart the engine.

But I don't know what the problem is.

 

Bad bad things are happening when that light is flashing. look at my trans post