Operation
1. OPERATION- The cruise control automatically controls vehicle speed and allows the vehicle to run at a constant speed without depressing the accelerator pedal.
- The cruise control module compares the actual vehicle speed detected by feedback signals from the speedometer with the speed set in the memory memorized when the set switch was turned on.
A signal is then transmitted according to the difference between the two speeds.
This signal is transmitted to the solenoid valve in the vacuum pump located at the engine compartment.
The movement of the actuator operates the throttle cam, thereby keeping the vehicle speed constant.
Component Location:
2. COMPONENT LOCATION
3. CONTROL AND OPERATION
Schematic:
4. SCHEMATIC
Cruise Control Circuit Schematic:
5. CIRCUIT DIAGRAM
System Construction:
6. SYSTEM CONSTRUCTION
7. VACUUM PUMP AND VALVE
- The vacuum pump activates when signal is emitted (current supply is ON) from cruise control module to supply the vacuum pressure to the cruise control system.
- The air valve shuts off the atmospheric pressure while the current supply is ON and retains the vacuum pressure in the actuator vacuum pressure chamber. When the current supply is interrupted, this valve opens and introduces the atmospheric pressure to the actuator chamber.
- The release valve blocks the atmospheric pressure while the current supply is ON, and introduces the atmospheric pressure when the current supply is OFF.
When cruise control is canceled, the air valve is opened simultaneously to introduce the atmospheric pressure for faster deceleration.
When the cruise control is out of operation, the air valve and release valve are opened and the vacuum pump is not activated. Therefore, the inside of the actuator is at atmospheric pressure, and the diaphragm does not operate.
During constant-speed driving with the cruise main switch ON, the air valve and vacuum pump are activated or not activated alternately while the release valve is closed in order to introduce a vacuum pressure or atmospheric pressure into the actuator.
In this condition, move the diaphragm, which operates the throttle cam to provide control over the vehicle speed.
How the vacuum pump and valves operate in response to signals from the cruise control module.
8. ACTUATOR
The diaphragm of actuator is operated by vacuum or atmospheric pressure applied through air valve or release valve, and this diaphragm movement actuates the cruise control cable via link to open or close the throttle valve. With the cruise control set to OFF (system OFF state), no diaphragm operation occurs as the atmospheric pressure governs inside the actuator.
9. MAIN SWITCH
- The main switch is the main power supply switch of the cruise control module and has a built-in power indicator and night illumination light.
- When the ignition switch is placed in the OFF position with the main switch at ON, the main switch is also simultaneously forced to OFF. In this condition, even if the ignition switch is placed in the ON position again, the main switch will stay in the OFF state.
10. COMMAND SWITCH
- When the vehicle is in the cruise control mode, the command switch controls its operation. It inputs SET/COAST signal, ACCEL/RESUME signal or CANCEL signal to the cruise control module.
- The command switch is located on the right side of the steering wheel and can be operated without releasing your hand from the steering wheel.
- The command switch is an auto return lever type.
- RESUME/ACCEL and SET/COAST switch
The switch is caused to be ON as long as the lever is kept pressed in any of the positions, and outputs it as a signal to the control module.
- CANCEL switch
The switch is caused to be ON as long as the lever is pulled toward CANCEL (toward you), and outputs RESUME/ACCEL and SET/COAST ON signals simultaneously.
11. CANCEL SIGNALS
The cancel signal cancels the cruise mode. When any of the following switches is operated, the cruise control module cancels the cruise mode.
- Stop light switch
- Brake switch
- Clutch switch (MT model)
- Inhibitor switch (AT model)
- Main switch
- Command switch (CANCEL position)
12. VEHICLE SPEED SENSOR 2
Vehicle speed sensor 2 is installed on the transmission, and sends signal to the cruise control module via speedometer.
13. ENGINE THROTTLE
- The throttle body is equipped with two throttle cams. One cam is used during acceleration and the other during cruising, in order to open or close the throttle valve.
- These cams operate independently of each other. In other words, while one cam operates, the other does not.
14. CONTROL MODULE
- Based on the signals from the individual switches, sensors, etc., the control module controls all of the cruise control functions described.
(Constant speed control, set control, deceleration control, acceleration control, resume control, manual cancel control, low speed limiter control, release valve control)
- To facilitate troubleshooting, provision has been made for compatibility with the select monitor.
15. FAIL-SAFE FUNCTION
1. Canceling function when CANCEL switch (signals) are in abnormal condition
- Group 1 switches: SET/COAST switch ON, RESUME/ACCEL switch ON and CANCEL switch ON.
- Group 2 switches: Brake switch OFF, Stop Light switch ON, Clutch switch OFF and Inhibitor switch ON
1. When at least one of the group 1 switches and one of the group 2 switches are operated simultaneously, the system is canceled and held in the non-operating state. When the switches in groups 1 and 2 are turned from ON to OFF (except brake and clutch switches which are turned from OFF to ON) and then the switches in group 1 are turned ON, the system starts operation.
2. If the cruise main switch is turned ON with at least one switch in group 1 turned ON, the system does not operate and remains in that state until the cruise main switch is turned OFF.
2. Canceling function when the system circuit is in abnormal condition
In the following states, the system is canceled and the memorized speed is also canceled. After cancellation of the system, the canceling function is held until the IG switch or cruise main switch is turned OFF.
1. The vacuum motor terminal is grounded or opened.
Or the vacuum motor driving circuit is shorted.
2. The air valve terminal is grounded or opened.
Or the air valve driving circuit is shorted.
3. The release valve terminal is grounded or opened.
Or the release valve driving circuit is shorted.
4. The vehicle speed signal varies more than ±10 km/h (6 MPH) per 350 m sec.
5. The fused internal relay is detected while the vehicle is not in cruise control operation.
6. The internal circuit of the cruise control module stops its operation is in abnormal condition.
7. There is a difference between memorized cruise speeds stored in two RAMs inside the cruise control module.
8. There is a difference between values showing output from the two RAMs inside the cruise control module.