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Cruise Control System (5-Series)

  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 At servo motor 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. 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 servo motor 7-pin connector disconnected, ground terminal No. 1 and apply battery voltage to terminal No. 6. Cruise control motor clutch should be heard switching. If not, replace servo motor.
  14. With servo motor 7-pin connector disconnected, ground terminal No. 2 and apply battery voltage to terminal No. 5. Cruise control motor should be heard running. If not, replace servo motor.
  15. If steps 12) through 13) test okay, replace control unit.
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