NOTE Airflow meter may also be referred to as Mass Airflow MAF meter

Airflow meter measures intake airflow volume. Input signal for airflow volume is sent from airflow meter to Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance), for controlling fuel injection system and oxygen sensor heater. Airflow meter also contains an intake air temperature sensor which is used to measure intake air temperature. See INTAKE AIR TEMPERATURE SENSOR .

Battery Signal (Avalon, Camry, Camry Solara, Celica, ECHO, Highlander, MR2, Prius, RAV4, Sienna, Tacoma, Tundra 3.4L V6 & 4Runner)

Battery voltage is always present at BATT terminal of Engine Control Module (ECM). When ignition is turned on, voltage for ECM operation is applied through EFI main relay to +B terminal on ECM. EFI main relay may also be referred to as EFI relay.

Battery Signal (Corolla)

Battery voltage is always present at BATT terminal of Engine Control Module (ECM). When ignition is turned on, voltage for ECM operation is applied through EFI main relay to +B terminal on ECM. EFI main relay may also be referred to as EFI relay or F-HTR relay.

Battery Signal (Land Cruiser)

Battery voltaae is always present at BATT and +BM terminals of Engine Control Module (ECM). When

2001 ENGINE PERFORMANCE Theory & Operation ignition is turned on, voltage for ECM operation is applied through EFI main relay to +B and +B1 terminals on ECM. EFI main relay may also be referred to as EFI relay or ECD relay. Voltage is applied to IGSW terminal on ECM through IGN fuse.

Battery Signal (Sequoia & Tundra 4.7L V8)

Battery voltage is always present at BATT and +BM terminals of Engine Control Module (ECM). When ignition is turned on, voltage for ECM operation is applied through EFI main relay to +B and +B1 terminals on ECM. EFI main relay may also be referred to as EFI relay. Voltage is applied to IGSW terminal on ECM through IGN fuse.

Brakelight Signal (Avalon, Camry With A/T, Camry Solara With A/T, Celica With A/T, Corolla With 4-Speed A/T, ECHO With A/T, Highlander, Land Cruiser, MR2, RAV4, Sequoia, Sienna, Tacoma With A/T, Tundra With A/T & 4Runner)

Brakelight switch delivers an input signal to STP terminal of ECM to indicate when brakes are applied. Input signal is mainly used for controlling fuel cut-off engine speed, as engine speed is slightly reduced when brakes are applied. Brakelight switch may also be referred to as stoplight switch.

Camshaft & Crankshaft Position Sensors (Avalon, Highlander 3.0L V6 & Sienna)

Camshaft position sensors and crankshaft position sensor deliver input signals to ECM. Camshaft position sensors may also be referred to Variable Valve Timing (VVT) sensors. Camshaft position sensors are located at flywheel end of each cylinder head, just below valve cover. Crankshaft position sensor is located at front of crankshaft, near crankshaft pulley. ECM may use input signals for determining ignition timing (spark advance), and for controlling fuel injection system, engine idle speed control system, Acoustic Control Induction System (ACIS) and VVT system.

Camshaft & Crankshaft Position Sensors (Camry 2.2L 4-Cyl. CNG & Gasoline Models, & Camry Solara 2.2L 4-Cyl.)

Camshaft position sensor and crankshaft position sensor deliver input signals to ECM. Camshaft position sensor is located at timing belt end of cylinder head, on firewall side of engine. Crankshaft position sensor is located behind lower timing belt cover, near crankshaft sprocket. ECM may use input signals for determining ignition timing (spark advance), and for controlling fuel injection system and engine idle speed control system.

Camshaft & Crankshaft Position Sensors (Camry 3.0L V6 & Camry Solara 3.0L V6)

Camshaft position sensor and crankshaft position sensor deliver input signals to ECM. Camshaft position sensor is located at flywheel end of front cylinder head, just below valve cover. Crankshaft position sensor is located at front of crankshaft, near crankshaft pulley. ECM may use input signals for determining ignition timing (spark advance), and for controlling fuel injection system, engine idle speed control system, EGR system, heated oxygen sensor system and Acoustic Control Induction System (ACIS).

Camshaft & Crankshaft Position Sensors (Celica, Corolla, ECHO, Highlander 2.4L 4-Cyl., MR2, Prius & RAV4)

Camshaft position sensor and crankshaft position sensor deliver input signals to Engine Control Module (ECM). Camshaft position sensor may also be referred to as Variable Valve Timing (VVT) sensor. On Celica, Corolla and MR2, camshaft position sensor is located just above intake manifold on cylinder head, at flywheel end of

2001 ENGINE PERFORMANCE Theory & Operation engine. On ECHO, Highlander, Prius and RAV4, camshaft position sensor is located on end of cylinder head at flywheel end of engine. On all models, crankshaft position sensor is located on front of engine, near crankshaft pulley. ECM may use input signals for determining ignition timing (spark advance), and for controlling fuel injection system, engine idle speed control system and VVT system.

Camshaft & Crankshaft Position Sensors (Land Cruiser & Sequoia)

Camshaft position sensor and crankshaft position sensor deliver input signals to Engine Control Module (ECM). Camshaft position sensor is located behind driver's side upper timing belt cover, near camshaft sprocket. Crankshaft position sensor is located at front of crankshaft, near crankshaft pulley. ECM may use input signals for determining ignition timing (spark advance) and for controlling fuel injection system.

Camshaft & Crankshaft Position Sensors (Tacoma 2.4L 4-Cyl. & 2.7L 4-Cyl.)

Camshaft position sensor and crankshaft position sensor deliver input signals to Engine Control Module (ECM). Camshaft position sensor is located at driver's side front corner of cylinder head, just in front of intake manifold. Crankshaft position sensor is located near crankshaft pulley, just above oil pan on driver's side of engine. ECM may use input signals for determining ignition timing (spark advance), and for controlling fuel injection system and heated oxygen sensor system.

Camshaft & Crankshaft Position Sensors (Tacoma 3.4L V6, Tundra 3.4L V6 & 4Runner)

Camshaft position sensor and crankshaft position sensor deliver input signals to Engine Control Module (ECM). Camshaft position sensor is located behind upper timing belt cover, near passenger's side camshaft sprocket. Crankshaft position sensor is located at front of engine, just above crankshaft pulley. ECM may use input signals for determining ignition timing (spark advance), and for controlling fuel injection system and heated oxygen sensor system.

Camshaft & Crankshaft Position Sensors (Tundra 4.7L V8)

Camshaft position sensor and crankshaft position sensor deliver input signals to Engine Control Module (ECM). Camshaft position sensor is located behind driver's side upper timing belt cover, near camshaft sprocket. Crankshaft position sensor is located at front of crankshaft, near crankshaft pulley. ECM may use input signals for determining ignition timing (spark advance) and for controlling fuel injection system.

Center Air Bag Sensor Assembly (Camry 2.2L CNG Models, Celica, Corolla, Highlander, MR2, RAV4, Sequoia & Sienna)

Center air bag sensor assembly delivers an input signal to Engine Control Module (ECM) if an airbag is deployed. If ECM detects that air bags are deployed, ECM will stop fuel pump operation by opening the circuit opening relay. This operation is referred to as fuel cut control. If fuel cut control has been activated, turning ignition switch from OFF position to ON position cancels the fuel cut control operation and fuel pump will operate. Center air bag sensor assembly may also be referred to as air bag sensor assembly.

Center Air Bag Sensor Assembly (Prius)

Center air bag sensor assembly delivers an input signal to Hybrid Vehicle (HV) control Electronic Control Unit (ECU) if an airbag is deployed. Hybrid vehicle control ECU is referred to as HV ECU. The HV ECU then

2001 ENGINE PERFORMANCE Theory & Operation delivers input signal to Engine Control Module (ECM). If air bags are deployed, ECM will stop fuel pump operation by opening the circuit opening relay. This operation is referred to fuel cut control. If fuel cut control has been activated, turning ignition switch from OFF position to ON position cancels the fuel cut control operation and fuel pump will operate. Center air bag sensor assembly may also be referred to as air bag sensor assembly.

EGR Gas Temperature Sensor (Camry 3.0L V6, Camry Solara 3.0L V6 & Tacoma 2.7L 4-Cyl. 3RZ-FE)

EGR gas temperature sensor monitors EGR gas temperature and delivers an input signal to Engine Control Module (ECM). EGR gas temperature sensor is located near EGR valve.

EGR Position Sensor (Camry 3.0L V6 & Camry Solara 3.0L V6)

EGR position sensor monitors movement of EGR valve and delivers an input signal to Engine Control Module (ECM). ECM uses this input signal to obtain the correct amount of EGR valve opening in relation to the engine operation. EGR position sensor may also be referred to as EGR valve position sensor. EGR position sensor is mounted on EGR valve.

Electrical Load Signal (Avalon, Camry 3.0L V6, Camry Solara 3.0L V6 & Sienna)

An input signal is delivered to ELS and ELS2 terminals of Engine Control Module (ECM) to indicate when high electrical output is required. This signal is delivered when items such as headlights or rear window defroster are turned on. ECM may use input signal to maintain proper engine idle speed.

Electrical Load Signal (Camry 2.2L 4-Cyl. CNG & Gasoline Models, Camry Solara 2.2L 4-Cyl., Land Cruiser, RAV4, Sequoia, Tacoma 2.4L 4-Cyl. & 2.7L 4-Cyl., & Tundra 4.7L V8)

An input signal is delivered to ELS terminal of Engine Control Module (ECM) to indicate when high electrical output is required. This signal is delivered when items such as rear window defroster or headlights are turned on. ECM may use input signal to maintain proper engine idle speed.

Electrical Load Signal (Corolla)

An input signal is delivered to ELS and ELS2 terminals of Engine Control Module (ECM) to indicate when high electrical output is required. This signal is delivered when items such as rear window defroster or headlights are turned on. ECM may use input signal to maintain proper engine idle speed.

Electrical Load Signal (ECHO)

On vehicles equipped for cold areas, an input signal is delivered to ELS terminal of Engine Control Module (ECM) to indicate when high electrical output is required. This may occur when HTR SUB1 relay is energized to provide voltage to Positive Temperature Coefficient (PTC) heater. PTC heater is a small electrical heater located in the heater core. PTC heater will be turned on when engine coolant temperature is less than 176°F (80° C), engine speed is greater than 1050 RPM, generator power ratio is less than 95 percent and heater temperature control switch is positioned in maximum heat range. ECM may use input signal to maintain proper engine idle speed.

Engine Coolant Temperature Sensor

2001 ENGINE PERFORMANCE Theory & Operation

Engine Coolant Temperature (ECT) sensor contains a built-in thermistor in which resistance varies according to engine coolant temperature. ECT delivers an input signal to THW terminal of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance), and for controlling fuel injection system, engine idle speed control system, heated oxygen sensor system (if equipped), EGR system (if equipped) and operation of electronically controlled transaxles/transmissions (if equipped). For ECT sensor location, see appropriate REMOVAL, OVERHAUL & INSTALLATION article.

Engine Cranking Signal (Avalon, Camry, Camry Solara, Celica, Corolla, ECHO, Highlander, Land Cruiser, MR2, RAV4, Sequoia, Sienna, Tacoma, Tundra & 4Runner)

While engine is cranking and voltage is applied to the starter, an input signal is also delivered to STA or NSW terminal of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance), and for controlling fuel injection system.

Fuel Pipe Fuel Pressure Sensor (Camry 2.2L 4-Cyl. CNG Models)

Fuel pipe fuel pressure sensor delivers input signal to Engine Control Module (ECM). ECM may use input signal to determine fuel line pressure for fuel gauge operation. Fuel pipe fuel pressure sensor may also be referred to as fuel pressure sensor (fuel pipe). Fuel pipe fuel pressure sensor is located near fuel pressure regulator located in the fuel line between fuel tank and the fuel rail, just below the brake booster. See Fig. 44 .

2001 ENGINE PERFORMANCE Theory & Operation

1992 Toyota Tercel Fuel Rail Install
Fig. 44: Locating Fuel Pipe Fuel Pressure Sensor, Fuel Pressure Regulator, Oil Separator & Fuel Pressure Regulator Fuel Shutoff Valve (Camry 2.2L 4-Cyl. CNG Models) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fuel Rail Fuel Pressure Sensor (Camry 2.2L 4-Cyl. CNG Models)

Fuel rail fuel pressure sensor delivers input signal to Engine Control Module (ECM). ECM may use input signal to help correct the fuel injection volume. Fuel rail fuel pressure sensor may also be referred to as delivery pipe fuel pressure sensor or fuel pressure sensor (delivery pipe). Fuel rail fuel pressure sensor is located on timing belt end of fuel rail, near discharge valve.

Fuel Rail Fuel Temperature Sensor (Camry 2.2L 4-Cyl. CNG Models)

Fuel rail fuel temperature sensor delivers input signal to Engine Control Module (ECM). ECM may use input signal to help correct the fuel injection volume. Fuel rail fuel temperature sensor may also be referred to as delivery pipe fuel temperature sensor or fuel temperature sensor (delivery pipe). Fuel rail fuel temperature sensor is located at center of the fuel rail.

Fuel Tank Fuel Temperature Sensor (Camry 2.2L 4-Cyl. CNG Models)

2001 ENGINE PERFORMANCE Theory & Operation

Fuel tank fuel temperature sensor delivers input signal to Engine Control Module (ECM). ECM may use input signal to determine fuel tank temperature for fuel gauge operation. Fuel tank fuel temperature sensor may also be referred to as fuel temperature sensor (fuel tank). Fuel tank fuel temperature sensor is located on end of fuel tank behind the rear seat, near fuel tank fuel shutoff valve. See Fig. 45 .

Dendor Maf Toyota Hilux Engine 3rz
Fig. 45: Locating Fuel Tank Fuel Temperature Sensor, Fuel Tank Fuel Shutoff Valve & Fuel Tank Valve Assembly (Camry 2.2L 4-Cyl. CNG Models) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Heated Oxygen Sensor (All Models)

Heated oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system. Some models may be equipped with more than one heated oxygen sensor. A heater is used to warm oxygen sensor to improve heated oxygen sensor detection operation. Heater is controlled by ECM.

2001 ENGINE PERFORMANCE Theory & Operation

Intake Air Temperature Sensor (Avalon, Camry 3.0L V6, Camry Solara 3.0L V6, Celica, Corolla, ECHO, Highlander, Land Cruiser, MR2, Prius, RAV4, Sequoia, Sienna, Tacoma, Tundra & 4Runner)

Intake air temperature sensor is located in airflow meter. Intake air temperature sensor measures incoming intake air temperature and delivers an input signal to THA terminal of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system.

Intake Air Temperature Sensor (Camry 2.2L 4-Cyl. CNG & Gasoline Models, & Camry Solara 2.2L 4-Cyl.)

Intake air temperature sensor is mounted in air cleaner housing. Intake air temperature sensor measures incoming intake air temperature and delivers an input signal to THA terminal of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system.

Knock Sensor (Avalon, Camry 3.0L V6, Camry Solara 3.0L V6, Highlander 3.0L V6, Land Cruiser, Sequoia, Sienna & Tundra 4.7L V8)

Knock sensors No. 1 and 2 monitor ignition knock conditions and deliver input signals to KNKR and KNKL terminals of Engine Control Module (ECM). ECM may use input signals for determining ignition timing (spark advance) and for controlling fuel injection system. For knock sensor location, see REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.

Knock Sensor (Camry 2.2L 4-Cyl. Gasoline Models, Camry Solara 2.2L 4-Cyl., Celica, Corolla, ECHO, Highlander 2.4L 4-Cyl., MR2, Prius, RAV4 & Tacoma 2.4L 4-Cyl. & 2.7L 4-Cyl.)

Knock sensor monitors ignition knock conditions and delivers input signal to KNK or KNK1 terminal of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system. For knock sensor location, see REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

Knock Sensor (Tacoma 3.4L V6, Tundra 3.4L V6 & 4Runner)

Knock sensors No. 1 and 2 monitor ignition knock conditions and deliver input signals to KNK1 and KNK2 terminals of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system. For knock sensor location, see REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.

Manifold Absolute Pressure Sensor (Camry 2.2L 4-Cyl. CNG & Gasoline Models, & Camry Solara 2.2L 4-Cyl.)

Manifold Absolute Pressure (MAP) sensor monitors intake manifold intake air volume and delivers an input signal to Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system. For MAP sensor location, see REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

Park/Neutral Position Switch (Avalon, Camry, Camry Solara, Celica, Corolla, ECHO, Highlander, Land Cruiser, RAV4, Sequoia, Sienna, Tacoma, Tundra & 4Runner)

Park/Neutral Position (PNP) switch is used only on A/T models. PNP switch delivers an input signal to Engine

2001 ENGINE PERFORMANCE Theory & Operation

Control Module (ECM) to indicate transaxle or transmission gear position. ECM may use input signal to control engine idle speed and fuel injection system. PNP switch is located on side of transaxle or transmission.

Park/Neutral Position Switch (Prius)

Park/Neutral Position (PNP) switch is used only for the hybrid vehicle control system, which controls the electric transaxle. PNP switch delivers an input signal to Hybrid Vehicle (HV) control Electronic Control Unit (ECU) to indicate transaxle gear position instead of the Engine Control Module (ECM) like all other models. Hybrid vehicle control ECU is referred to as HV ECU. The HV ECU uses input signal for controlling vehicle movement. PNP switch is located on end of shift lever assembly on steering column and may also be referred to as shift position sensor.

Power Steering Pressure Sensor (ECHO)

Power steering pressure sensor delivers an input signal to ECM to indicate power steering pressure. ECM may use input signal to control engine idle speed. Power steering pressure sensor may also be referred to as power steering oil pressure sensor. Power steering pressure sensor is located on side of power steering pump.

Power Steering Pressure Switch (Avalon, Camry, Camry Solara, Celica, Corolla, Highlander, RAV4, Sienna, Tacoma, Tundra 3.4L V6 & 4Runner)

Power steering pressure switch delivers an input signal to Engine Control Module (ECM) to indicate power steering pressure. ECM may use input signal to control engine idle speed. Power steering pressure switch may also be referred to as power steering oil pressure switch. Power steering pressure switch is located on power steering pump or near pressure hose at power steering pump.

Temperature Control Switch (ECHO)

On vehicles equipped for cold areas, temperature control switch operates a maximum hot switch which provides an input signal to Engine Control Module (ECM) for controlling Positive Temperature Coefficient (PTC) heater. PTC heater is a small electrical heater located in the heater core. Maximum hot switch may also be referred to as MAX HOT switch. For additional information on PTC heater, see POSITIVE TEMPERATURE COEFFICIENT HEATER under MISCELLANEOUS CONTROLS.

Throttle Position Sensor (Avalon, Camry, Camry Solara, Celica, Corolla, ECHO, Highlander, 2000 MR2, 2001 MR2 With Standard Type Manual Transaxle, RAV4, Sienna, Tacoma & Tundra 3.4L V6)

Throttle Position (TP) sensor is located on throttle body. TP sensor delivers an input signal indicating throttle position to Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance), and for controlling fuel injection system, idle speed control system and various other systems.

Throttle Position Sensor (Land Cruiser, 2001 MR2 With Sequential Manual Transaxle, Prius, Sequoia, Tundra 4.7L V8 & 4Runner)

Throttle Position (TP) sensor is used with Electronic Throttle Control System (ETCS) for control of the throttle operation. See ELECTRONIC THROTTLE CONTROL SYSTEM under AIR INDUCTION SYSTEMS for additional information.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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Responses

  • Otho
    Where is the oil pressure valve located 2004 toyota tundra?
    7 years ago
  • KATRIN
    Where is fuel pressure regulator on 1998 Toyota Camry 2.2L?
    7 years ago
  • s
    Where is the ocv circuit on a 2001 toyota sienna 3.0 L?
    5 years ago
  • ona
    How to change a 2001 tacoma 4cyl temperature coolant sensor?
    4 years ago
  • uwe
    Is the intake side camshaft sensor the same as the mass airflow meter sensor?
    3 years ago
  • weronika
    Where to find open circuit relay hilux 2.7l?
    3 years ago
  • tewelde
    How to install petrol pipes of corolla 1992?
    2 years ago
  • temesgen
    Where is the fuel pressure regulator on a 2001 toyota camry 2.2?
    2 years ago
  • Olli-Pekka
    Where is thecòolant temperature sensor located on a 3rz engine (Toyota)?
    2 years ago

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