LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> BMW >> 1984 >> 633CSi Standard >> Repair and Diagnosis >> Accessories & Equipment >> Cruise Control Systems >> Testing >> Cruise Control System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Cruise Control System

  1. Check fuse and contacts. Replace fuse or clean contacts as required. Check stop light bulbs and contacts. Replace bulbs or clean contacts as required. Ensure cruise control cable is properly adjusted and not damaged. Ensure motor and strap operate with easy movement.
  2. Ensure brake and clutch switches are properly adjusted. Check all wires and wiring connectors for damage and proper fit. Repair or replace as required.
    NOTE: Steps 3) through 10) are performed with wiring connector disconnected at cruise control unit.
  3. Using an ohmmeter, measure resistance value between ground and terminal No. 23 of connector. If reading is not 0 ohms, repair ground connection.
  4. Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 1 of connector. Voltmeter should display battery voltage. If battery voltage is not displayed, repair power supply circuit.
  5. Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 2 of connector. Voltmeter should display battery voltage. If voltage is not as specified, check and repair cruise control switch, control unit, or wiring. Move cruise control switch to "OFF" position. Voltage reading should now be 0 volts. If voltage reading is not as specified, replace cruise control switch.
  6. Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 4 of connector. Voltmeter should display 0 volts. If voltage is not as specified, check and repair cruise control switch, control unit, or wiring. Hold switch in "CONSTANT" position. Voltage reading should now be battery voltage. If voltage reading is not as specified, replace cruise control switch.
  7. Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 5 of connector. Voltmeter should display 0 volts. If voltage is not as specified, check and repair cruise control switch, control unit, or wiring. Hold switch in "RESUME" position. Voltage reading should now be battery voltage. If voltage reading is not as specified, replace cruise control switch.
  8. Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 9 of connector. Voltmeter should display 0 volts. If voltage is not as specified, replace brake switch.
  9. With ignition on and voltmeter connected as in step 8), depress brake pedal. Voltmeter should display battery voltage. If voltage reading is not as specified, pull both plugs from stop light switch. Connect ohmmeter and depress brake pedal. Ohmmeter reading should display 0 ohms. Repeat procedure for clutch switch. Replace switch if readings are not as specified.
  10. Connect frequency meter between terminal Nos. 3 and 6 of connector. Raise vehicle and start engine. Place vehicle in gear and increase speed to about 30 MPH. Frequency reading should be about 84 Hz. If reading is not as specified, check speed transmitter and wiring.
  11. Connect wiring connector to cruise control unit and disconnect 7-pin wiring connector. Connect voltmeter between terminal Nos. 4 and 3. Turn ignition on. Voltage reading should be about 8 volts. If reading is not as specified, replace control unit.
  12. With 7-pin connector disconnected, connect voltmeter between terminal Nos. 3 and 7. Turn ignition on. Voltage reading should be about 8 volts. If reading is not as specified, replace cruise control motor.
  13. With 7-pin connector disconnected, apply battery voltage to connector; ground to No. 1 terminal (White wire) and positive to No. 6 terminal (Green wire). Cruise control motor clutch should be heard to switch. If not, replace motor.
  14. With 7-pin connector disconnected, apply battery voltage to connector; ground to No. 2 terminal (Blue wire) and positive to No. 5 terminal (Black wire). Cruise control motor should be heard to operate. If not, replace motor.
  15. If steps 12) through 13) test okay, replace control unit.
scientia non olet · About LEMON Manuals