ASCD Cannot Be Set (Set Indicator Lamp Blinks/Fail-Safe System)

ASCD CANNOT BE SET (SET INDICATOR LAMP BLINKS/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
- Stop lamp switch
- Park/neutral position relay
- Park/neutral position switch
- 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 is pressed or A/T selector lever is in N or P. Confirm that ON is indicated 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.