I have a 99 Ram 2500 with the 24 valve cummins and 4 spd auto, the overdrive off button on my truck does not work, so if it has to kick down it kicks way down instead of simply being able to take it out of overdrive, i cannot find any fuses blown under the hood or in interior box, I tow a jeep on a 20 ft flatbed and it just kills me to pull hills. My truck has a small lift and 35 inch tiresl, it doesnt do anything when thei hit the button, no light on the dash,would it be just the switch or could my problem be more trouble, perhaps a sylenoid on the tranny?