under the dash above the emergency brake pedal is a light blue colored box, inside that is a reset button that you can insert a small screwdriver to press it and the light will be reset.
From inside the trunk.
Disconnect the negative battery cable for five minutes. This will reset the light, but if the problem that caused the light to be set is not repaired the light will just come back on.
The sensor is threaded into the head to the left of the thermostat housing and has a single wire connector on it. Thanks Malcolm
Disconnect the neg cable from the battery for a moment or two. This will reset the light but it will come back on if the reason the light came on in the first place wasn't fixed.
disconnect the battery for a few minutes
get a new transmission
Disconnect the battery for 20 minutes. This should reset the light. Of course if you do not repair the problem that caused the light to come on in the first place, it will just come back on.
Take it to Autozone (or your local parts store) and they will connect the scan tool to your truck, then you will press reset.
Disconnect the battery for 5 minutes. This should reset the light. It will however come right back on unless you have found and repaired the problem that caused the computer to set the light in the first place.
Disconnect the negative battery connection for 30 minutes and the light will reset. However it will come back on if you have not repaired the problem that caused it to come on in the first place.
pull down glove box small relay on right side slide push in small red button to reset