Cruise Control

POWER SUPPLY VALVE, VACUUM PUMP, AIR VALVE OR RELEASE VALVE

System Description
The 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 the ASCD actuator to control the throttle cable.

Possible Cause
- Vacuum motor
- Air valve
- Release valve
- Circuit open or short

Diagnostic Repair Procedure (for confirmed incidents)
1. 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.
a Replace ASCD control unit.
2. Check resistance of vacuum motor, release valve and air valve: Vacuum motor = approx. 3 Ohm, release valve and air valve = approx. 65 Ohm
3. Check circuit between ASCD pump and ASCD control unit: Continuity/No shorts to ground/No continuity to each other.

VHCL SP-S/FAIL SAFE

System Description
ASCD control unit receives an input signal from the speedometer. ASCD control unit uses this input signal to set the selected cruise speed and maintain it.

Possible Cause
- Vehicle speed sensor
- Speedometer
- Circuit open or short

Diagnostic Repair Procedure (for confirmed incidents)
1. 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

CONTROL UNIT

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.

Possible Cause
- Control unit

Diagnostic Repair Procedure (for confirmed incidents)
1. Erase SELF-DIAG RESULTS.
2. Test drive vehicle using ASCD functions.
3. Recheck SELF-DIAG RESULTS: If CONSULT-II displays CONTROL UNIT, replace ASCD control unit.

BRAKE SW/STOP/L SW

System Description
ASCD operation is canceled by pressing the clutch or brake pedal or by shifting A/T selector lever to P or N position.
For M/T models power is supplied to control unit through ASCD brake switch and ASCD clutch switch. For NT models power is supplied to control unit through ASCD brake switch and park/neutral position relay. If this power is cut at any point in the circuit ASCD operation is canceled.
When brake pedal is pressed, power is supplied from stop lamp switch to ASCD control unit. This will also cancel ASCD operation.

Possible Cause
- 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.

COMMAND SW

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. And 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 cancel operation other than depressing MAIN switch is performed, vehicles 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 increases until the switch is released. And 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: Using 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.

ECM
System Description
During ASCD cruise, ASCD control unit controls A/T shifting to avoid uncomfortable shifting. This control is
used throttle position sensor signal from ECM and A/T shift solenoid valve A signal.

Possible Cause
- ECM
- Circuit open or short

Diagnostic Repair Procedure (for confirmed incidents)
1. Check circuit between ASCD control unit and ECM.
2. Check ECM.