ECD SYSTEM SYSTEM DESCRIPTION

1. Diesel Clean Advanced Technology (TOYOTA D-CAT) comprehensively regulates engine control (consisting of a catalytic system and a fuel injection system) that purifies both particulate matter (PM) and nitrogen oxides (NOx) discharged by diesel engines. The catalytic system purifies hydrocarbons (HC) and carbon monoxides (CO), and reduces PM and NOx with a catalytic converter with the Diesel Particulate-NOx Reduction system (DPNR). The fuel injection system adds fuel into the exhaust port using the exhaust fuel addition injector to produce a rich state for NOx reduction and maintain a proper catalyst temperature for DPNR catalyst regeneration.

   

   Text in Illustration

   *1	ECM	*2	Injector Driver (EDU)
   *3	Common Rail	*4	Fuel Pressure Sensor
   *5	Pressure Discharge Valve	*6	Fuel Supply Pump
   *7	VSV for EGR Cooler	*8	EGR Cooler
   *9	Injector	*10	EGR Valve Assembly
   *11	Diesel Throttle Body Assembly	*12	Turbocharger
   *13	Exhaust Fuel Addition Injector	*14	DPNR Catalytic Converter
   *15	Differential Pressure Sensor	*16	Exhaust Gas Temperature Sensor (B1S1)
   *17	Exhaust Gas Temperature Sensor (B1S2)	*18	Air Fuel Ratio Sensor
   *19	Oxidation Catalyst Converter	*20	Fuel Tank

2. TOYOTA D-CAT components:

   Component	Description
   DPNR catalytic converter	Reduces HC, CO, PM, and NOx.
   Exhaust fuel addition injector	Adds the fuel into the exhaust port in order to produce a rich air-fuel ratio for NOx reduction. Also raises the catalyst temperature for DPNR catalyst regeneration.
   Exhaust gas temperature sensor	Used for estimating the DPNR catalytic converter temperature and adjusting fuel addition by ECM while DPNR catalyst regeneration is performed. Also detects the DPNR catalytic converter temperature to prevent the catalytic converter temperature from rising too high.
   Differential pressure sensor	Detects the volume of PM deposits and any incorrect vacuum hose arrangement on the DPNR catalytic converter.
   A/F sensor	Used for controlling the air-fuel ratio. By controlling the air-fuel ratio, combustion control for low temperature combustion and DPNR catalyst regeneration are properly regulated.

3. Diagnostic Trouble Code (DTC) table for TOYOTA D-CAT:

   Tech Tips

   This table indicates typical DTC combinations for each malfunction occurrence.

   Trouble Area	Malfunction	DTC No.
   DPNR catalytic converter	Deteriorated or clogged	P2002, P1601, P1386*
   Exhaust fuel addition injector	Stuck open	P1386
   	Stuck closed	P1386, P2002*
   	Low fuel addition volume	P1386, P2002*
   	Open in exhaust fuel addition injector circuit	P1386, P2047, P2002*
   	Short in exhaust fuel addition injector circuit	P1386, P2047
   	Open or short in exhaust fuel addition injector circuit	P1386, P2047, P2002*
   Exhaust gas temperature sensor	Open in exhaust gas temperature sensor circuit	P0545, P0546, P1386, P2032, P2033
   	Short in exhaust gas temperature sensor circuit	P0545, P0546, P1386*, P2002*, P2032, P2033
   	Exhaust gas temperature sensor	P0545, P0546, P1386*, P2032, P2033
   Differential pressure sensor	Open in differential pressure sensor circuit	P2002*, P2454, P2455
   	Short in differential pressure sensor circuit	P2002*, P2454, P2455
   	Differential pressure sensor	P2002*, P2454, P2455
   	Differential pressure sensor clogged	P2002*, P2453
   	Incorrect vacuum hose arrangement of the differential pressure sensor	P2002*, P2453
   A/F sensor	Open or short in A/F sensor or heater circuit	P0031, P0032, P1386*, P2238, P2239, P2252, P2253
   	A/F sensor	P0031, P0032, P1386*, P2238, P2239, P2252, P2253
   Exhaust gas leaks	Exhaust gas leaks	P1386*, P2002*
   Fuel leaks	Fuel leaks in fuel addition injector	P1386*
   Fuel supply pump	Correct fuel pressure cannot be fed to the exhaust fuel addition injector	P1386*

   *: There may be no DTC output depending on the condition of the malfunction.

4. Diagnostic trouble code description for TOYOTA D-CAT:

   DTC No.	Description
   P0031	Open or short in A/F sensor heater control circuit (Low output)
   P0032	Open or short in A/F sensor or heater circuit (High output)
   P0545	Open or short in exhaust gas temperature sensor circuit (B1S1) (Low output)
   P0546	Open or short in exhaust gas temperature sensor circuit (B1S1) (High output)
   P1386	TOYOTA D-CAT fuel addition system malfunction
   P2002	DPNR catalytic converter malfunction
   P2032	Open or short in exhaust gas temperature sensor circuit (B1S2) (Low output)
   P2033	Open or short in exhaust gas temperature sensor circuit (B1S2) (High output)
   P2047	Open in exhaust fuel addition injector circuit
   P2238	Open or short in A/F sensor or heater circuit (Low output)
   P2239	Open or short in A/F sensor or heater circuit (High output)
   P2252	Open or short in A/F sensor or heater circuit (Low output)
   P2253	Open or short in A/F sensor or heater circuit (High output)
   P2453	Differential pressure sensor is clogged or has incorrect vacuum hose arrangement
   P2454	Open or short in differential pressure sensor circuit (Low output)
   P2455	Open or short in differential pressure sensor circuit (High output)

1. Common rail system:

   The common rail system uses high-pressure fuel for improved fuel economy. This system also provides robust engine power while suppressing engine vibration and noise.

   This system stores fuel in the common rail, which has been pressurized and supplied by the supply pump. By storing fuel at high-pressure, the common rail system can provide fuel at stable fuel injection pressures, regardless of engine speed or engine load.

   The ECM, using the EDU, provides an electric current to the piezo actuator in each injector to regulate the fuel injection timing and volume. The ECM also monitors the internal fuel pressure of the common rail using the fuel pressure sensor. The ECM causes the supply pump to supply the fuel necessary to obtain the target fuel pressure.

   In addition, this system uses a piezo actuator inside each injector to open and close the fuel passages. Therefore, both fuel injection time and fuel injection volume can be precisely regulated by the ECM.

   The common rail system allows a two stage fuel injection process. In order to soften combustion shock, this system performs "pilot-injection" prior to the main fuel injection. This helps to reduce engine vibration and noise.

   

   Tech Tips

   If there is a problem with a fuel return pipe, as bleeding air from the fuel system may not be able to be performed properly in certain instances, such as after replacing a fuel injector, etc., the engine startability may deteriorate.

2. Common rail system components:

   Component	Description
   Common rail	Stores high-pressure fuel produced by supply pump
   Fuel supply pump	Operated by crankshaft Supplies high-pressure fuel to common rail
   Injector	Injects fuel to combustion chamber based on signals from ECM
   Fuel pressure sensor	Monitors internal fuel pressure of common rail and sends signals to ECM
   Pressure discharge valve	Based on signals from ECM, opens valve when sudden deceleration occurs, or when ignition switch is off to prevent fuel pressure from becoming too high.
   Suction control valve	Based on signals from ECM, adjusts fuel volume supplied to common rail and regulates internal fuel pressure
   Check valve	Keeps pressure that discharges from injector

3. Diagnostic trouble code (DTC) table for the common rail system:

   Tech Tips

   This table indicates typical DTC combinations for each malfunction occurrence.

   Trouble Area	Malfunction	DTC No.
   Injector	Open or short in injector circuit	P062D, P1238, P0093*
   	Stuck open	P0093, P1238
   	Stuck closed	P1238
   Fuel pressure sensor	Open or short in fuel pressure sensor circuit or pressure sensor output fixed	P0087, P0190, P0191, P0192, P0193
   Pressure discharge valve	Open or short in pressure discharge valve circuit	P1271, P1272, P0088*, P0093*, P1229*
   	Stuck open	P0093
   	Stuck closed	P1272, P0088*
   Suction control valve	Open or short in suction control valve circuit	P0627, P1229, P0088*
   	Stuck open	P1229, P0088*
   EDU	Faulty EDU	P0093*, P062D*, P1238*, P1271*, P1272*
   Common rail system (Fuel system)	Fuel leaks in high-pressure area	P0093

   *: There may be no DTC output depending on the condition of the malfunction.

4. Diagnostic trouble code description for the common rail system:

   DTC No.	Description
   P0087	Fuel pressure sensor output does not change
   P0088	Internal fuel pressure too high (200000 kPa [2039.4 kgf/cm2, 29000 psi] or more)
   P0093	Fuel leaks in high-pressure areas
   P0190	Open or short in fuel pressure sensor circuit (output voltage is too low or too high)
   P0192	Open or short in fuel pressure sensor circuit (output voltage is too low)
   P0193	Open or short in fuel pressure sensor circuit (output voltage is too high)
   P062D	Open or short in EDU or injector circuit
   P0627	Open or short in suction control valve circuit
   P1229	Fuel over-feed

The ECM controls the fuel injection system through the EDU, injectors and supply pump.

The ECM determines the injection volume and injection timing based on signals from the accelerator pedal position sensor, crankshaft position sensor and camshaft position sensor. Based on the signals from the ECM, the EDU controls the injectors. The EDU also controls the suction control valve installed on the supply pump to help regulate fuel pressure.

The piezo type injector used in the 2AD-FHV engine makes noise when the engine is idling because this injector operates at high speed. Therefore, the EDU controls the injector to operate at low speed when the engine is idling based on signals from the ECM to achieve noise reduction.

The feed pump is used to pump fuel from the fuel tank to the supply pump.

The rotation of the eccentric cam in the supply pump causes the ring cam in the supply pump to push plunger A upward as illustrated below. The spring force pulls plunger B (located opposite to plunger A) upward. As a result, plunger B draws fuel in, and plunger A pumps fuel out at the same time.

1. Small opening of the suction control valve:

   
   

   1. When the opening of the suction control valve is small, the volume of supplied fuel is small.

   2. The suction volume becomes small due to the narrow path despite the plunger stroke being full. The difference between the geometrical volume and suction volume creates a vacuum.

   3. Pump output will start when the fuel pressure at (A) becomes higher than the common rail pressure (B).

      

2. Large opening of the suction control valve:

   
   

   1. When the opening of the suction control valve is large, the volume of supplied fuel is large.

   2. If the plunger stroke is full, the suction volume becomes large because of the wide path.

   3. Pump output will start when the fuel pressure at (A) becomes higher than the common rail pressure (B).