1996 Ford F150 Owner's Manual - Page 105

If you drive up or down a steep hill, your vehicle may momentarily slow down or speed up, even though the speed control is on. This is normal. NOTE: If your speed increases above your set speed while driving in j (Overdrive) on a downhill grade, you may want to depress the transmission control switch located on the shift lever to turn off overdrive to reduce vehicle speed. Speed control cannot reduce the vehicle speed if it goes above your set speed on a downhill grade. For the best fuel economy during normal driving conditions, leave the shift select in j (Overdrive), or resume as soon as practical. RWARNING Do not use the speed control in heavy traffic or on roads that are winding, slippery, or unpaved. In mountainous areas, at higher elevations, or when pulling a trailer, the speed control may not be able to maintain the preset speed with the transmission in overdrive. If your vehicle comes with a 5-speed manual transmission, you may prefer to drive in 4 (Fourth) gear, in mountainous areas or at high altitudes, to improve speed control performance. In order to downshift (with a manual transmission) with the speed control operating, you must press either the brake or clutch pedal long enough to disengage the speed control. Wait a second before depressing the clutch again and making the shift so that the speed control can fully return to the idle position. 103