Cruise Control: Testing and Inspection

ASCD CANNOT BE SET (CRUISE INDICATOR LAMP DOES NOT ON)

System Description
ASCD allows the driver to maintain speeds between 40 kph (25 MPH) and 144 kph (89 MPH) without using the accelerator pedal. ASCD control unit uses inputs from speedometer and controls ASCD actuator. ASCD actuator will use the signals from ASCD control unit to maintain the driver's desired set speed.
When ASCD main switch is depressed, ASCD control unit holds CRUISE condition and illuminates CRUISE indicator lamp.

Possible Cause
- ASCD steering switch (MAIN)
- Circuit open or short

Diagnostic Repair Procedure (for confirmed incidents)
1. Check power supply to ASCD control unit terminal 5: With ignition switch ON, battery voltage should exist.
2. Check ground circuit to ASCD control unit.
3. Check ASCD steering (MAIN) switch input signal: Use CONSULT-II DATA MONITOR, confirm that MAIN SW indicates ON when MAIN switch is pressed. Confirm that OFF is indicated when MAIN switch is released.
a. Check ASCD main switch: Continuity through the switch in ON position/No continuity in OFF position.
b. Check circuit between ASCD control unit and ASCD MAIN switch.

ASCD CANNOT BE SET (SET INDICATOR LAMP DOES NOT BLINK)

System Description
ASCD allows the driver to maintain speeds between 40 kph (25 MPH) and 144 kph (89 MPH) without using the accelerator pedal. ASCD control unit uses inputs from speedometer and controls ASCD actuator. ASCD actuator will use the signals from ASCD control unit to maintain the driver's desired set speed.
When ASCD main switch is depressed, ASCD control unit holds CRUISE condition and illuminates CRUISE indicator lamp.
When SET/COAST switch is pressed and released, ASCD is activated. SET indicator lamp will illuminate and vehicle will automatically maintain the speed of vehicle at the time the switch was pressed.

Possible Cause
- ASCD steering switch (SET/COAST RESUME/ACCEL, CANCEL)
- Vehicle speed sensor
- ASCD brake switch
- ASCD clutch switch (M/T)
- Stop lamp switch
- Park/neutral position relay (A/T)
- Park/neutral position switch (A/T)
- Circuit open or short

Diagnostic Repair Procedure (for confirmed incidents)
1. Check ASCD brake switch input signal: Using CONSULT-II DATA MONITOR, confirm that BRAKE SW indicates OFF when brake pedal or clutch pedal is pressed (M/T), or when brake pedal is pressed or A/T selector lever is in N or P (A/T). Confirm that ON is indicated when brake pedal and clutch pedal are released (M/T), or when brake pedal is released and A/T selector lever is not in N or P.
a. Check power supply to ASCD brake switch with ignition switch ON: Spec = Battery voltage.
b. Check ASCD brake switch: Continuity through it in the released position and no continuity through it in the depressed position.
c. Check ASCD clutch switch (M/T models): Continuity through it in the released position and no continuity through it in the depressed position.
d. Check power supply to park/neutral position switch (A/T models): Spec = Battery voltage.
e. Check park/neutral position switch (A/T models): Continuity through it in either P or N position, and no continuity through it in any other position.
f. Check park/neutral position switch circuit: Continuity/No shorts to ground.
g. Check park/neutral position relay (A/T models): Use normal methods for relay testing.
h. Check ASCD brake switch circuit: Continuity/No shorts to ground.
2. Check stop lamp switch input signal: Use CONSULT-II DATA MONITOR to confirm that STOP LAMP SW indicates OFF when brake pedal is released and ON when brake pedal is depressed.
a. Check power supply to stop lamp switch.
b. Check stop lamp switch: Continuity through it in the depressed position and no continuity through it in the released position.
c. Check between stop lamp switch and ASCD control unit: Continuity/No shorts to ground.
3. Check ASCD steering switch input signal: Use CONSULT-II DATA MONITOR, confirm that SET SW, RESUME/ACC SW and CANCEL SW indicates ON when each switch is pressed. Confirm that OFF is indicated when each switch is released.
a. Check power supply ASCD steering switch: This power supply comes through the coil of the horn relay. If horn operates properly power supply is OK.




b. Check ASCD steering switch:
Check continuity between terminals by pushing each switch.
c. Check circuit between ASCD steering switch and ASCD control unit.
4. Check vehicle speed sensor input signal: Use CONSULT-II DATA MONITOR to confirm that VHCL SPEED SE indicates actual vehicle speed.
a. Check speedometer operation: It speedometer is not operating properly, repair as necessary.
b. Check circuit between ASCD control unit and combination meter: Continuity/No shorts to ground.

ASCD CANNOT BE SET (SET INDICATOR LAMP BLINK / FAIL-SAFE SYSTEM)

System Description
When the fail-safe system senses a malfunction, it deactivates ASCD operation. The SET indicator lamp in combination meter will then blink.

Possible Cause
- ASCD steering switch (SET/COAST, RESUME/ACCEL, CANCEL)
- ASCD pump
- Vehicle speed sensor
- ASCD brake switch
- ASCD clutch switch (M/T)
- Stop lamp switch
- Park/neutral position relay (A/T)
- Park/neutral position switch (A/T)
- Circuit open or short
- ASCD control unit

Diagnostic Repair Procedure (for confirmed incidents)
1. With ignition switch ON, turn ASCD main switch OFF and then ON and wait 1 minute. SET indicator lamp should not blink.
a. Check ASCD steering switch input signal: Use CONSULT-II DATA MONITOR, confirm that SET SW, RESUME/ACC SW and CANCEL SW indicates ON when each switch is pressed. Confirm that OFF is indicated when each switch is released.
b. Check power supply ASCD steering switch: This power supply comes through the coil of the horn relay. If horn operates properly power supply is OK.




c. Check ASCD steering switch:
Check continuity between terminals by pushing each switch.
2. While driving the vehicle at more than 40 kph (25 MPH) with ASCD main ON, press SET/COAST switch. SET indicator lamp should not blink.
a. Check vehicle speed sensor input signal: Use CONSULT-II DATA MONITOR to confirm that VHCL SPEED SE indicates actual vehicle speed.
- Check speedometer operation: If speedometer is not operating properly, repair as necessary.
- Check circuit between ASCD control unit and combination meter: Continuity/No shorts to ground.
b. Check power supply to ASCD pump from ASCD control unit: Use CONSULT-II DATA MONITOR to confirm that PW SUP-VALVE indicates ON when ASCD is operating and OFF when ASCD is not operating.
c. Check resistance of vacuum motor, release valve and air valve:
Vacuum motor = approx. 3 Ohm, release valve and air valve = approx. 65 Ohm.
d. Check circuit between ASCD pump and ASCD control unit: Continuity/No shorts to ground/No continuity to each other.
3. While driving vehicle with ASCD set, slowly press brake pedal for more than five seconds. SET indicator lamp should not blink.
a. Check ASCD brake switch input signal: Use CONSULT-II DATA MONITOR, confirm that BRAKE SW indicates OFF when brake pedal or clutch pedal is pressed (M/T), or when brake pedal is pressed or A/T selector lever is in N or P (A/T). Confirm that ON is indicated when brake pedal and clutch pedal are released (M/T), or when brake pedal is released and A/T selector lever is not in N or P.
b. Check stop lamp switch input signal: Use CONSULT-II DATA MONITOR to confirm that STOP LAMP SW indicates OFF when brake pedal is released and ON when brake pedal is depressed.

ASCD STEERING SWITCH (SET/COAST, RESUME/ACCEL, CANCEL) WILL NOT OPERATE

System Description
ASCD steering switch allows the driver to supply power to ASCD control unit to control ASCD operation.
When SET/COAST switch is pressed, power is supplied to ASCD control unit.
- When SET/COAST switch is pressed and released, ASCD is activated. SET indicator lamp will illuminate and vehicle will automatically maintain the speed of vehicle at the time the switch was pressed.

- When SET/COAST switch is depressed during cruise control driving, vehicle set speed is reduced until the switch is released. ASCD will keep the new set speed.
- If SET/COAST switch is pressed and released quickly during cruise control driving, vehicle set speed will be reduced by 1.6 kph (1.0 MPH).
When RESUME/ACCEL switch is pressed, power is supplied to ASCD control unit.
- When RESUME/ACCEL switch is depressed after cancelling operations other than depressing MAIN switch, vehicle speed will return to last set speed.
- If RESUME/ACCEL switch is pressed and released quickly during cruise control driving, vehicle set speed will increase by 1.6 kph (1.0 MPH).
- When RESUME/ACCEL switch is depressed during cruise control driving, vehicle set speed increase until the switch is released. ASCD will keep the new set speed.
When CANCEL switch is pressed, power is supplied to ASCD control unit.
- Pressing CANCEL switch will cancel cruise operation.

Possible Cause
- ASCD steering switch (SET/COAST, RESUME/ACCEL, CANCEL)
- Horn relay
- Circuit open or short

Diagnostic Repair Procedure (for confirmed incidents)
1. Check ASCD steering switch input signal: Use CONSULT-II DATA MONITOR, confirm that SET SW, RESUME/ACC SW and CANCEL SW indicates ON when each switch is pressed. Confirm that OFF is indicated when each switch is released.
a. Check power supply ASCD steering switch: This power supply comes through the coil of the horn relay. If horn operates properly power supply is OK.




b. Check ASCD steering switch:
Check continuity between terminals by pushing each switch.
c. Check circuit between ASCD steering switch and ASCD control unit.

LARGE DIFFERENCE BETWEEN SET SPEED AND ACTUAL VEHICLE SPEED AND/OR SET SPEED HUNTS

System Description
ASCD allows the driver to maintain speeds between 40 kph (25 MPH) and 144 kph (89 MPH) without using the accelerator pedal. ASCD control unit uses inputs from speedometer and controls ASCD pump. ASCD pump will use the signals from ASCD control unit to maintain the driver's desired set speed.
ASCD pump consists of a vacuum motor, an air valve and a release valve. Input signals from the ASCD control unit controls ON/OFF operation of the vacuum motor, air valve and release valve. The pump is connected to ASCD actuator by vacuum hose. When the ASCD pump is activated, the ASCD pump vacuums the diaphragm of ASCD actuator to control throttle cable.

Possible Cause
- ASCD actuator
- ASCD pump
- Vehicle speed sensor
- ASCD control unit

Diagnostic Repair Procedure (for confirmed incidents)
1. Check vacuum hose between ASCD actuator and hose: No cracks or leaks.
2. Check ASCD wire: Smooth operation and adjustment.
3. Check ASCD actuator: Use a hand vacuum pump to apply -40 kPa (-40.2 kg/sq.cm, -5.8 psi). Wait 10 seconds and confirm that vacuum pressure decrease is less than 2.7 kPa (0.028 kg/sq.cm, 0.40 psi).
4. Check resistance of vacuum motor, release valve and air valve:
Vacuum motor = approx. 3 Ohm, release valve and air valve = approx. 65 Ohm.




5. Check ASCD pump operation: Disconnect vacuum hose from ASCD pump connector. Then connect vacuum gauge to ASCD pump and apply 12 V direct current to ASCD pump.
6. Check vehicle speed sensor input signal: Use CONSULT-II DATA MONITOR to confirm that VHCL SPEED SE indicates actual vehicle speed.
a. Check speedometer operation: If speedometer is not operating properly, repair as necessary.
b. Check circuit between ASCD control unit and combination meter: Continuity/No shorts to ground.