ASCD Cannot Be Set (Set Indicator Lamp Does Not Blink)

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
- Stop lamp switch
- Park/neutral position relay
- Park/neutral position switch
- 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 is pressed or A/T selector lever is in N or R Confirm that ON is indicated 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 power supply to park/neutral position switch: Spec = Battery voltage.
d. Check park/neutral position switch: Continuity through it in either P or N position, and no continuity through it in any other position.
e. Check park/neutral position switch circuit: Continuity/No shorts to ground.
f. Check park/neutral position relay: Use normal methods for relay testing.
g. 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: If speedometer is not operating properly, repair as necessary.
b. Check circuit between ASCD control unit and combination meter: Continuity/No shorts to ground.