I have a 1997 1/2 ton excab 4x4 5.9 automatic and on the drive home the engine light came on and the overdrive light came on also . I have changed the speed sensor and the filter/fluid and no changes. I disconected the battery to reset the codes but nothing changed . Tranny will not let me take off in Drive it just slips I have to start in low and manually shift it to drive.
You need to get an OBD-II code reader, and retrieve those codes. They'll tell you what's wrong. It sounds like your transmission has gone into limp mode, and without any other info., I'd guess your governor pressure sensor has crapped out.
If you're not comfortable with doing some pressure tests, dropping the pan, and changing some parts on the valve body, then take it to a transmission shop - it's not that expensive of a fix.
The last sentence points to a failed overrunning clutch (sprag), placing the shifter in 1 applies the rear band which performs the same function as the sprag.
Is there a "tinny" sound when attempting to take off in Drive? Was there any hard debris found when the pan was removed.
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