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Cruise Control Systems: Description

WARNING: Vehicle is equipped with Supplemental Inflatable Restraint (SIR) system. When servicing vehicle, use care to avoid accidental air bag deployment. SIR system related components are located in various locations throughout interior and exterior of vehicle, depending on application. Do not use electrical test equipment on or near these circuits. Before attempting ANY repairs involving steering column, instrument panel or related components, or If necessary, deactivate SIR system before servicing components. See AIR BAG SAFETY PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS.
NOTE: For fuse locations, see FUSES & CIRCUIT BREAKERS article in ELECTRICAL.

System Outline 

The current is applied at all times through the STOP fuse to TERMINAL 2 of the stop light SW. For stop light switch terminal identification, see step 2 of DTC 12: ACTUATOR MAGNETIC CLUTCH CIRCUIT  under DIAGNOSTIC TESTS.

With the ignition SW turned to on, the current flows through the GAUGE fuse to TERMINAL 9 of the integration relay to terminal (A) 9 to Terminal (D) 2 of the combination meter and the current through the ECU-IG fuse flows to TERMINAL 9 of the cruise control ECU. See Fig 1.

When the ignition SW is on and the cruise SW is turned on, see Fig 2, a signal is input from TERMINAL 5 of the cruise control SW to TERMINAL 11 of the cruise control ECU. As a result, the cruise control ECU functions and the current flows from the ECU-IG fuse to TERMINAL 9 of the cruise control ECU to TERMINAL 16 of the cruise control ECU to GROUND, and the cruise control system is in a condition ready for operation.

At the same time, the current through the GAUGE fuse flows to TERMINAL 9 of the integration relay to TERMINAL (A) 9 to TERMINAL (D) 2 of the cruise control indicator light to TERMINAL (A) 7 to TERMINAL 4 of the cruise control ECU to TERMINAL 16 to GROUND, causing the cruise control indicator light to light up, see Fig 3, indicating that cruise control is ready for operation.

  1. Set Operation -  When the cruise control main SW, see Fig 2, is pushed with the vehicle speed within the set limit (Approx. 25 mph. (40 km/h) to 124 mph (200 km/h), a signal is input to terminal 10 of the cruise control ECU and the vehicle speed at the time the set SW is released is memorized in the ECU as the set speed.
  2. Set Speed Control -  During cruise control driving, the ECU compares the set speed memorized in the ECU with the actual vehicle speed input into TERMINAL 12 of the cruise control ECU from the speed sensor via combination meter, and controls the cruise control actuator to maintain the set speed.

    When the actual speed is lower than the set sped, the ECU causes the current to the cruise control actuator to flow from TERMINAL 15 of the cruise control ECU to TERMINAL 1 of the cruise control actuator to TERMINAL 2 to TERMINAL 7 of the cruise control ECU. As a result, the motor in the cruise control actuator is rotated to open the throttle valve and the throttle cable is pulled to increase the vehicle speed. When the actual driving speed is higher than the set speed, the current to the cruise control actuator flows from TERMINAL 7 of the ECU to TERMINAL 2 of the cruise control actuator to TERMINAL 1 to TERMINAL 15 of the cruise control ECU.

    This causes the motor in the cruise control actuator to rotate to close the throttle valve and return the throttle cable to decrease the vehicle speed.

  3. Coast Control -  During cruise control driving, while the COAST SW is on, see Fig 4, the cruise control actuator returns the throttle cable to close the throttle valve and decrease the driving speed. The vehicle speed when the coast SW is turned off is memorized and the vehicle continues at the new set speed.
  4. Accel Control -  During cruise control driving, while the ACCEL SW is turned on, the cruise control actuator pulls the throttle cable to open the throttle valve and increase the driving speed.

    The vehicle speed when the ACCEL SW is turned off is memorized and the vehicle continues at the new set speed.

  5. Resume Control -  Unless the vehicle falls below the minimum speed limit (Approximately 25 mph. (40 km/h.)) after cancelling the set speed by the cancel SW, pushing the resume SW, see Fig 5, pushing the resume SW will cause the vehicle to resume the speed set before cancellation.
  6. Manual Cancelling Mechanism -  If any of the following operations occurs during cruise control operation, the magnetic clutch of the actuator turns off and the motor rotates to close the throttle valve and the cruise control is released.
    • Placing the shift lever to positions except "D" position (Park/Neutral position SW except "D" position)(A/T), Depressing the clutch pedal (Cruise control clutch SW off)(M/T). "Signal is not input to TERMINAL 3 of the ECU".
    • Depressing the brake pedal (Stop light SW on). Signal input to TERMINAL 2 of the ECU".
    • Pushing the cancel SW (Cancel SW on). "Signal input to TERMINAL 10 of the ECU".
    • Pushing the CRUISE SW off "signal input to TERMINAL 11 of the ECU".
  7. Tap-Up Control Function -  When the difference between the actual vehicle speed and the set speed is less than 3 mph (5 km/h), the set speed can be increased 1.0 mph (1.6 km/h.) each time by operating the RESUME/ACCEL SW quickly within 0.6 seconds. See Fig 5.
  8. Tap-Down Control Function -  When the difference between the actual vehicle speed and the set speed is less than 3 mph (5 km/h), the set speed can be lowered 1.0 mph (1.6 km/h.) each time by operating the SET/COAST SW quickly within 0.6 seconds.
  9. Auto Cancel Function - 
    1. If any of the following operating conditions occurs during cruise control operation, the set speed is erased, current flow to the magnetic clutch is stopped and the cruise control is released. (CRUISE SW turns off).

      When this occurs, the ignition SW must be turned off once before the main CRUISE SW will turn on.

      • When current continued to flow to the motor inside the actuator in the throttle valve "OPEN" direction.
      • The motor does not operate despite the motor drive signal being output.

    2. If any of the following operating conditions occurs during cruise control operation, the set speed is erased, the current flow to the magnetic clutch is stopped and the cruise control is released. (CRUISE SW turn off).

      When this occurs, the cancel state is cleared as the CRUISE SW will turn on again.

      • Over current to transistor driving the motor and/or the magnetic clutch.
      • Open circuit in the magnetic clutch.
      • Momentary interruption of vehicle speed signal.
      • Short circuit in the cruise control switch.
    3. If any of the following conditions occurs during cruise control operation, the set speed is erased and the cruise control is released. (The power to the magnetic clutch is cut off until the SET SW is "ON" again.)
      • When the vehicle speed falls below the minimum speed limit, approx. 25 mph (40 km/h).
      • When power to the cruise control system is momentarily cut off.
  10. Automatic Transaxle Control Function - 
    • In overdrive. If the vehicle speed becomes lower than the overdrive cut speed (set speed minus approx. 2.5 mph (4 km/h.)) during cruise control operation, such as driving up a hill, the overdrive is released and the power increased to prevent a reduction in vehicle speed.
    • After releasing the overdrive, if the vehicle speed becomes higher than the overdrive return speed (Set speed minus approx. 1.2 mph. (2 km/h)) and the ECU judges by the signals from the actuators potentiometer that the upward slope has finished, the overdrive is resumed after approximately 2 seconds.
    • During cruise control driving, the cruise control operation signal is output from the cruise control ECU to the engine control module. Upon receiving this signal, the engine control module changes the shift pattern to normal.

      To maintain smooth cruise control operation (on a downward slope etc.), the lock-up release to the transaxle when the idling point of the throttle position is "ON" is forbidden.

Fig 1: Identifying ECU Terminals & Voltages
G00368730Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Identifying Cruise Control On & Off Button (Main Switch)
G00330434Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 3: Locating Instrument Panel Cruise Control Indicator Lamp
G00368727Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 4: Identifying Set/Coast Setting
G00330436Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 5: Identifying Res/Acc Setting
G00330437Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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