Brake Switch (Cruise Control): Testing and Inspection

Perform this test only when brake application will not disconnect the speed control system.
1. Check operation of stop lamps by applying approximately 6 lbs. of pressure to brake pedal. If more than 6 lbs. is required, check brake pedal actuation and stop lamp switch.
2. If stop lamps do not function properly, check bulbs, circuit fuse or stop lamp switch.
3. If stop lamps function properly, check for battery voltage at 6 way connector using black wire w/green stripe on 1980 models, 1981-83 E-100-350 and 1984-87 E-150-350 series, or white wire w/pink stripe on 1981-82 F-100-350 and Bronco series, or white wire w/purple stripe on 1983 F-100-350, Bronco and Ranger, 1984-87 F-150-350, Ranger, 1984-87 Bronco II and 1986-87 Aerostar.
4. Depress brake pedal until stop lamps are illuminated. Check voltage at red wire w/black stripe on 1980 models, 1981-83 E-100-350 and 1984-87 E-150-350 models, or the light green wire on 1981-83 F-100-350 and Bronco, 1984-87 F-150-350 and Bronco, 1983-87 Ranger, 1984-87 Bronco II and 1986-87 Aerostar. The difference between the two voltage readings must not exceed 1.5 volts. If voltage is greater, a high resistance exists in the circuit and must be found and corrected.