1996 Ford Thunderbird Owner's Manual - Page 100

Speed Control (If equipped) If your vehicle has speed control, you can automatically maintain a constant speed at or above 30 mph (50 km/h). Use of radio transmitting equipment that is not Federal Communications Commission (FCC) or in Canada the Canadian Radio and Telecommunications Commission (CRTC) approved may cause the speed control to malfunction. Therefore, use only properly installed FCC (CRTC in Canada) approved radio transmitting equipment in your vehicle. NOTE: When driving in hilly terrain, at high elevations, or when pulling a trailer, it may be desirable to drive with the transmission in the Overdrive off mode. This can be done by depressing the Transmission Control Switch on the transmission gear selection lever. Driving in this mode prevents the transmission from shifting excessively when ascending grades, and helps maintain speed when going down steep hills. NOTE: Do not shift to N (Neutral) when using the speed control. This will cause the engine to overspeed. When driving uphill, especially with a heavy load, significant speed drops may occur. If the speed drops more than 10 mph (16 km/h) the automatic speed control will, by design, be suspended. Some vehicles may require temporary resumption of manual speed control while ascending steep grades in order to maintain the selected speed. 97