Transmission Problem

I have a 99 ext cab 4X4 new body style. I was driving home and out of the blue it shifts into Drive and won't shift back into OverDrive. When I came to a stop and took off it was in 2nd so I shifted it into 1st and it was like it was gone. Then the service engine light came on. I was wondering if there is a shift sensor for each gear or a fuse. Thanks for any info, Jim

Sounds like a problem with 1-2 shift solenoid. It must be energized for 1st and energized for 4th. It is not energized for 2nd or 3rd. You could have it scaned to check for codes or you could pull the pan and check the solenoid and connection. The two square soleniods toward the back are the 1-2 and 2-3 shift solenoids. Sorry I don't know which is which but check the connections on both. The connectors get brittle from heat and can become loose. If the connections look good I would check or replace the solenoids.