CONSTRUCTION AND OPERATION

SYSTEM OUTLINE

The cruise control section in engine-ECU calculates the auto-cruise control operation condition based on the signals sent from switches and sensors. Based on the calculation, the cruise control section outputs the target accelerator pedal opening angle signal to the engine control section, and "CRUISE" indicator ON/OFF signal to the "CRUISE" indicator light. If either one of the stoplight switch or clutch switch of the cancel system is turned ON, the "CRUISE" indicator light ON/OFF signal is turned OFF, and then the "CRUISE" indicator light goes out. Therefore, the auto-cruise control is cancelled.
The engine-ECU calculates the auto-cruise control system operation status when the control section of the auto-cruise control system inside the engine-ECU receives the input signals of the auto-cruise control switch, vehicle speed, and cancel system (stoplight switch and clutch switch). To the engine control section it sends the target accelerator angle value for auto-cruise control system, and to the gauge it issues an ON/OFF command for the "CRUISE" indicator light.
In the engine control section, the injector operating time is calculated based on the target accelerator pedal opening angle signal from the cruise control section and the actual accelerator pedal opening angle signal, and the vehicle speed is controlled by controlling the fuel injection amount from the injector.
In the engine control section, the target throttle angle value is calculated from the target acceleration value for auto-cruise control system and the actual accelerator angle value, and the vehicle speed is controlled by applying the injectors.
BLOCK DIAGRAM

"SET/COAST" SWITCH FUNCTION

SET FUNCTION

1.While driving in the vehicle speed range of approximately 40 to 200 km/h, press down the auto-cruise control switch, and then release the hand from the switch.
2.The cruise control stores the vehicle speed when the switch is released, and then performs a constant speed driving at the stored vehicle speed.
3.When the switch is operated within the vehicle speed range of approximately 200 to 210 km/h, the vehicle speed of approximately 200 km/h becomes the new stored speed, and then the constant speed driving is performed at that speed. When the switch is operated while driving at the vehicle speed of approximately 210 km/h or faster, the constant speed driving is not performed.

COAST FUNCTION

1.When the auto-cruise control switch is pressed down for 0.5 seconds or more during the constant speed driving, the vehicle is decelerated while the switch is pressed up.
2.After that, when the hand is released from the switch, the vehicle speed of that time is newly stored, and then the constant speed driving is performed at that speed.
3.In addition, when the auto-cruise control switch is pressed down for less than 0.5 seconds, the vehicle speed is decreased by 1.6 km/h from that of the constant speed driving. The decelerated speed is newly stored, and then the constant speed driving is performed at that speed.
4.When the auto-cruise control switch is pressed down and held, and the vehicle speed is decelerated to approximately 35 km/h or less, the set function and coast function are released, and the constant speed driving is cancelled.

"ACC/RES" SWITCH FUNCTION

RESUME FUNCTION

1.During the constant speed driving, pull the auto-cruise control switch toward you or depress the brake pedal to cancel the constant speed driving.
2.Afterward, when the auto-cruise control switch is pressed up while driving at a vehicle speed of approximately 40 km/h or more, a constant speed driving is performed at the vehicle speed stored when the constant speed driving was cancelled.

ACCEL FUNCTION

1.When the auto-cruise control switch is pressed up for 0.5 seconds or more during the constant speed driving, the vehicle is accelerated with the specified acceleration while the switch is pressed up.
2.After that, when the hand is released from the switch, the vehicle speed of that time is newly stored, and then the constant speed driving is performed at that speed.
3.In addition when the auto-cruise control switch is pressed up for less than 0.5 seconds, the vehicle speed is increased by 1.6 km/h from that of the constant speed driving. The accelerated vehicle speed is newly stored, and then the constant speed driving is performed at that speed.
4.It is possible to accelerate the vehicle speed to approximately 200 km/h or more by pressing up and holding the auto-cruise control switch. However, after the hand is released from the switch, the vehicle speed of approximately 200 km/h becomes a newly stored vehicle speed, and then the constant speed driving is performed at that speed.

CANCEL FUNCTION

When any of the following conditions occur, the auto-cruise control is cancelled.

When the "ON/OFF" switch at the auto-cruise control switch is pressed to stop the auto-cruise control system.
When the "CANCEL" switch at the auto-cruise control switch is pressed to stop the auto-cruise control system.
When the brake pedal is depressed.
When the clutch pedal is depressed.
When the vehicle speed becomes approximately 35 km/h or less.
When the vehicle speed is decreased by 15 km/h or more from the starting speed of the constant speed driving.
When an abnormality occurs in the vehicle speed signal.
When TCL/ASC is activated.
When the engine coolant temperature becomes abnormally high.
When an abnormality occurs to the engine-ECU.

FAIL-SAFE FUNCTION

When any of the following conditions are met and do not activate auto-cruise control, and if the requirements are met during auto-cruise control, auto-cruise control is cancelled instantly. At this time, after the regular state is restored, auto-cruise control is possible again.

"SET" or "RESUME" switch held ON for 60 seconds or more.
Fault in cancel state holding circuit.
If vehicle speed is 40 km/h or more, vehicle speed signal fails to be input for 0.1 second or longer.
When an abnormality occurs to the stoplight switch.
When an abnormality occurs to the clutch switch.

When any of the following conditions are met, until the ignition is switched OFF once, do not activate auto-cruise control. If the requirements are met during auto-cruise control, auto-cruise control is cancelled instantly.

Defective engine-ECU
Defective accelerator pedal position sensor
CAN communication abnormality between engine-ECU and ABS-ECU or engine-ECU and TCL/ASC-ECU

SELF-DIAGNOSIS AND SERVICE DATA OUTPUT FUNCTIONS

To simplify the system check, the following functions that can be diagnosed using M.U.T.-III are provided.

Diagnosis code set
Diagnosis code erase
Service data output

DIAGNOSIS CODE CHART

Code No.	Major contents of diagnosis
P0504	Brake switch correction
P0573	Brake switch high
P0578	Cruise control switch stuck
P0579	Cruise control switch range
P1574	Engine-ECU

note

When reading the diagnosis code using M.U.T.-III, do not select the item under "CRUISE CONTROL," but select the item under "ENGINE." Then, check the above diagnosis code among the engine-related diagnosis codes.

HOW TO ERASE DISPLAY DIAGNOSIS CODE

Erase the diagnosis code using M.U.T.-III.

SERVICE DATA OUTPUT

The service data output is shown in the following.

Items No.	Service data item		Unit
1D	Auto-cruise control switch	"MAIN"	ON/OFF
		"SET/COAST"	ON/OFF
		"RESUME/ACCELERATING"	ON/OFF
		"CANCEL"	ON/OFF
	Auto-cruise control operation		ON/OFF
	Clutch pedal position switch		ON/OFF
	Brake switch		ON/OFF
	Stoplight switch		ON/OFF
01	Vehicle speed signal		km/h
04	Accelerator pedal position sensor		mV
12	Cancel code		Displays a cancel code number.

note

If two or more actions are taken at the same time, codes are set in ascending order of code number.