Cruise Control System
- Check fuse No. 6 (fuse No. 15 on 735i series vehicles) and contacts. Replace fuse or clean contacts as required. Check stop light bulbs and contacts. Replace bulbs or clean contacts as required. Ensure control cable is properly adjusted and not damaged. Ensure motor and strap operate with easy movement.
- 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 control unit.
- Using an ohmmeter, measure resistance (X) between ground and terminal No. 23 of connector. If reading is not zero ohms, repair ground connection.
- 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.
- Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 2 of connector. Voltmeter should display battery voltage. If not, check and repair cruise control switch, control unit, or wiring. Move cruise control switch to "OFF" position. Voltage reading should now be zero volts. If not, replace cruise control switch.
- Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 4 of connector. Voltmeter should display battery voltage. If not, check and repair cruise control switch, control unit, or wiring. Hold switch in "CONSTANT" position. Battery voltage should be present. If not, replace cruise control switch.
- Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 5 of connector. Voltmeter should display zero volts. If not, check and repair cruise control switch, control unit, or wiring. Hold switch in "RESUME" position. Voltage reading should now be battery voltage. If not, replace cruise control switch.
- Turn ignition on. Using a voltmeter, measure voltage between ground and terminal No. 9 of connector. Voltmeter should display zero volts. If not, replace brake switch.
- 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 zero ohms. Repeat procedure for clutch switch. Replace switch if readings are not as specified.
- Connect frequency meter between connector terminals No. 3 and 6. Raise vehicle and start engine. Place vehicle in gear and increase speed to about 30 MPH. Frequency reading should be about 84 Hz. If not, check speed transmitter and wiring.
- Connect wiring connector to control unit and disconnect 7-pin wiring connector at control motor. Connect voltmeter between terminals No. 3 and 4. Turn ignition on. Voltage reading should be about 8 volts. If not, replace control unit.
- With 7-pin connector disconnected, connect voltmeter between terminals No. 3 and 7. Turn ignition on. Voltage reading should be about 8 volts. If not, replace control motor.
- With 7-pin connector disconnected, apply battery voltage to terminal No. 6 (Green wire), and ground terminal No. 1 (White wire). Control motor clutch should be heard to switch. If not, replace motor.
- With 7-pin connector disconnected, apply battery voltage to terminal No. 5 (Black wire) and ground pin No. 2 (Blue wire). Control motor should operate. If not, replace motor.
- If steps 12) through 14) test okay, replace control unit.