FUEL SYSTEM (DFI) 3-43

Self-Diagnosis

Backups

○The ECU takes the following measures to prevent engine damage when the DFI, ignition or immobilizer system parts have troubles.

	Service	Parts	Output Signal Usable	Backups by ECU
	Codes		Range or Criteria
				If the main throttle sensor system fails (the
		Main Throttle	Output Voltage	output voltage is out of the usable range,
	11			wiring short or open), the ECU locks ignition
		Sensor	0.2 4.8 V
				timing into the ignition timing at closed throttle
				position and sets the DFI in the D-J method.
		Inlet Air	Inlet Air Pressure	If the inlet air pressure sensor #1 system fails
				(the signal is out of the usable range, wiring
	12	Pressure	(Absolute)
				short or open), the ECU sets the DFI in the
		Sensor #1	Pv = 100 900 mmHg
				α-N method (1).
		Inlet Air	Inlet Air Temperature	If the inlet air temperature sensor system fails
	13	Temperature		(the signal is out of the usable range, wiring
			Ta = – 47 + 178°C
		Sensor		short or open), the ECU sets Ta at 40°C.
		Water		If the water temperature sensor system fails
			Water Temperature	(the signal is out of the usable range, wiring
	14	Temperature
			Tw = – 30 + 120°C	short or open), the ECU sets Tw at 80°C and
		Sensor		the radiator fan operates.
		Inlet Air	Atmospheric Pressure	If the inlet air pressure sensor #2 system fails
				(the signal is out of the usable range, wiring
	16	Pressure	(Absolute)
				short or open), the ECU sets Pa at 760 mmHg
		Sensor #2	Pa = 100 900 mmHg
				(the standard atmospheric pressure).
		Crankshaft	Crankshaft sensor must	If the crankshaft sensor fails, the engine stops
	21		send 22 signals to the ECU
		Sensor	at the 1 cranking.	by itself.
		Speed	Speed sensor must send 8	If the speed sensor system fails (no signal,
	24		signals to the ECU at the 1	wiring short or open), the speedometer shows
		Sensor
			rotation of the output shaft.	0.
		Gear	Output Voltage	If the gear position switch system fails (no
	25	Position		signal, wiring short or open), the ECU set the
			0.2 4.8 V
		Switch		top (6th) gear position.
				If the vehicle-down sensor system has failures
		Vehicle	Output Voltage	(the output voltage is out of the usable range,
	31	-down		wiring short or open), the ECU shuts off the
			0.10 4.84 V
		Sensor		fuel pump relay, the fuel injectors (primary and
				secondary) and the ignition system.
				If the subthrottle sensor system fails (the
		Subthrottle	Output Voltage	output voltage is out of the usable range, wiring
	32			short or open), the ECU drive the subthrottle
		Sensor	0.15 4.84 V
				valve to the full closed position, and it stops
				the current to the subthrottle valve actuator.
		Oxygen	The oxygen sensor is
			active and sensor must
		Sensor		If the oxygen sensor is not activated, the ECU
	33		send signals (output
		(Equipped		stops the feedback mode of the oxygen sensor.
			voltage) continuously to
		Models)
			the ECU.

3-44 FUEL SYSTEM (DFI)

Self-Diagnosis

	Service	Parts	Output Signal Usable	Backups by ECU
	Codes		Range or Criteria
		Exhaust		If the exhaust butterfly valve actuator sensor
				system fails (the output voltage is out of the
		Butterfly
			Output Voltage	usable range, wiring short or open), the ECU
	34	Valve
			0.1 4.8 V	drive the exhaust butterfly valve at full open
		Actuator
				position near, and it stops the current to the
		Sensor
				exhaust butterfly valve actuator.
		Immobilizer
	35	Amplifier	–	If the immobilizer system fails (no signal, wiring
		(Equipped		short or open), the vehicle is no start and run.
		Models)
		Master or
	36	User Key	The user or master key	If the blank key or broken key is used, the
		(Equipped	must use register key.	vehicle is no start and run.
		Models)
			The ECU send the data
	39	ECU	(for gear position, service	–
			code and key registration)
			to the meter unit.
			The stick coil primary	If the stick coil #1 primary winding has failures
	51	Stick Coil #1*	winding must send	(no signal, wiring short or open), the ECU
			signals 20 or more times	shuts off the injector #1 to stop fuel to the
			continuously to the ECU.	cylinder #1, though the engine keeps running.
			The stick coil primary	If the stick coil #2 primary winding has failures
	52	Stick Coil #2*	winding must send	(no signal, wiring short or open), the ECU
			signals 20 or more times	shuts off the injector #2 to stop fuel to the
			continuously to the ECU.	cylinder #2, though the engine keeps running.
			The stick coil primary	If the stick coil #3 primary winding has failures
	53	Stick Coil #3*	winding must send	(no signal, wiring short or open), the ECU
			signals 20 or more times	shuts off the injector #3 to stop fuel to the
			continuously to the ECU.	cylinder #3, though the engine keeps running.
			The stick coil primary	If the stick coil #4 primary winding has failures
	54	Stick Coil #4*	winding must send	(no signal, wiring short or open), the ECU
			signals 20 or more times	shuts off the injector #4 to stop fuel to the
			continuously to the ECU.	cylinder #4, though the engine keeps running.
		Radiator Fan	When the relay OFF
	56		condition, the fan relay is	–
		Relay	open.
		Subthrottle	The actuator operates	If the subthrottle valve actuator fails (the
			open and close of the	signal is out to the usable range, wiring short
	62	Valve
			subthrottle valve by the	or open), the ECU stops the current to the
		Actuator
			pulse signal from the ECU.	actuator.
		Exhaust	The actuator operates	If the exhaust butterfly valve actuator fails (the
			open and close of the
		Butterfly		signal is out to the usable range, wiring short
	63		exhaust butterfly valve by
		Valve		or open), the ECU stops the current to the
			the pulse signal from the
		Actuator		actuator.
			ECU.
			The air switching valve
		Air Switching	controls the flow of the
	64		secondary air by opening	–
		Valve	and shutting the solenoid
			valve.

				FUEL SYSTEM (DFI) 3-45
	Self-Diagnosis
	Service	Parts	Output Signal Usable	Backups by ECU
	Codes		Range or Criteria
		Oxygen	The oxygen sensor heater	If the oxygen sensor heater fails (wiring short
		Sensor
			raise temperature of	or open), the ECU stops the current to the
	67	Heater
			the sensor for its earlier	heater, and it stops the feedback mode of the
		(Equipped
			activation.	oxygen sensor.
		Models)
		Oxygen	The oxygen sensor is
			active and sensor must
		Sensor		If the oxygen sensor is not activated, the ECU
	94		send signals (output
		(Equipped		stops feedback mode of the oxygen sensor.
			voltage) continuously to
		Models)
			the ECU.

Note:

(1) α-N Method: the DFI control method from medium to heavy engine load. When the engine load is light like at idling or low speed, the ECU determines the injection quantity by calculating from the throttle vacuum (inlet air pressure sensor #1 output voltage) and engine speed (crankshaft sensor output voltage). This method is called D-J method. As the engine speed increases, and the engine load turns middle to heavy, the ECU determines the injection quantity by calculating from the throttle opening (main throttle sensor output voltage) and the engine speed. This method is called α-N method.

*: This depends on the number of stopped cylinders.