Powertrain control module (RSM)
19. Based on the information it receives from the sensors described above, the PCM controls the pulse width of the fuel injectors (cyclic feed), idle speed, ignition timing, ignition coil primary current flow time, EVAP canister purge, and many other functions and parameters. It does this by controlling the output agents. The following is a brief description of the purpose, location, and operation of each of the important output actuators.
Output actuators
20. Variable valve timing oil control valve - Variable valve timing oil control valve is an element of an intelligent variable valve timing system (WT-t), which changes the opening or closing of the valves depending on the operating conditions of the engine, in order to increase torque, reduce fuel consumption and reduce harmful emissions. The intake valves are advanced or retarded using a hydraulic device, known as the WT-i controller, which is installed at the end of each intake camshaft. The variable valve timing oil control valve contains a spool valve that controls the flow of oil supplied to the advance or retard side of the controller on each intake camshaft. The spool valve is controlled by a coil located inside the oil control valve. On four-cylinder engines, there is one variable valve timing oil control valve. It is located on the right rear corner of the cylinder head (where is the timing chain located) next to the WT-i controller which is mounted on the right end of the intake camshaft. V6 engines have two variable valve timing oil control valves located at the left end of the cylinder heads (on the driver's side) next to the WT-i controllers, which are mounted on the left ends of the intake camshafts. For more information about the WT-i system, see chapter 2A (four-cylinder engines) or 2B (V6 engines).
21. Canister shut-off valve - The canister shut-off valve is part of the EVAP system (EVAP). This valve opens and closes the fresh air line of the EVAP system (between air filter housing and EVAP canister), responding to signals from the powertrain control module (RSM). When commanded by the PCM, the canister shutoff valve also closes the EVAP canister for a check test. The canister shut-off valve is located in the engine compartment on the underside of the air filter housing.
Note. On earlier Lexus and Toyota models, this device is referred to as the vacuum switch valve (VSV) for canister stop valve (CCV). However, in this book it is simply referred to as the canister shut-off valve.
22. Canister purge valve - The canister purge valve is an element of the fuel vapor recovery system (EVAP). When the engine is cold or still warm, accumulated fuel vapors are not allowed to exit the EVAP canister. After the engine warms up, the PCM activates the canister purge valve, which controls the vapor flow from the canister to the intake manifold. The vapor flow is controlled by the purge valve in response to commands from the PCM, which controls how long the valve is on. On V6 models, the EVAP canister purge valve is located in the engine compartment, on the right side of the engine (where is the timing belt located). For more information about the EVAP system, see paragraph 19.
Note. On earlier Toyota and Lexus models, the purge valve was referred to as the vacuum changeover valve (VSV) for EVAP or VSV for EVAP. However, in this book it is referred to as the canister purge valve or purge valve.
23. Electronic Throttle Body - 2004 and later models equipped with Intelligent Electronic Throttle Control (ETCS-i). There is no conventional cable-actuated throttle body on these vehicles. Instead, an electronic throttle is used, which is controlled by the powertrain control module (RSM). The throttle valve, located in a suitable housing, is opened and closed by a throttle motor controlled by the PCM. Also missing is the cruise control cable and idle air valve (IAC). Cruise control and idle speed are controlled electronically in the PCM. The electronic throttle body is equipped with a throttle position sensor (TR), but this sensor is an integral part of the throttle body and cannot be replaced separately from it. The PCM determines the correct throttle angle by processing the input signal from the accelerator pedal position sensor (APP), which is located on the top edge of the accelerator pedal (see «Accelerator pedal position sensor» in paragraph 6).
24. Fuel injectors - PCM opens fuel injectors in sequence (in the order of the cylinders). In addition, the PCM controls the injector pulse duration, that is, the amount of time each injector remains open. Injector impulse duration (measured in milliseconds) determines how much fuel is supplied to the cylinders (i.e. cyclic fuel supply). For more information on the fuel system and fuel injectors (including injector replacement) refer to chapter 4.
25. Fuel Pump Relay - On Lexus and Toyota models, the fuel pump relay is also referred to as the opening relay because it controls the electrical circuits of not only the fuel pump, but also other elements of the fuel system. After being grounded by a signal from the PCM, the fuel pump relay supplies battery voltage to the fuel pump (and to other elements of the fuel system). On Lexus models, the fuel pump relay is usually located in the fuse and relay box in the engine compartment. On Toyota models, it is usually located in the #1 relay box, which is located in the fascia behind the lower section of the trim panel. The location of the relay may vary depending on the model and year of the vehicle. Therefore, if you cannot find it, refer to the fuse and relay chart given in the owner's manual that came with your vehicle.
26. Idle air valve (IAC) - PCM controlled IAC valve on all 1999-2003 models. located on the throttle body controls the amount of air that bypasses the throttle when the engine is idling. The PCM opens and closes the IAC valve in response to loads such as air conditioning and power steering to keep the idle speed at the desired level. The IAC valve also increases idle speed during the early stages of warm-up and acts as a damper when the throttle closes sharply during sudden deceleration. 2004 and later vehicles do not have an IAC valve. These models are equipped with an electronic throttle that does not require an IAC valve to control idle speed.
27. Coil (And) Ignition Coils - All ignition coils used on the vehicles covered in this manual are direct ignition coils. Each spark plug has its own coil mounted directly on the spark plug. There are no spark plug wires, and there is no separate ignition control module. This function is implemented by the powertrain control module (RSM). For more information on ignition coils, see chapter 5.
28. Valve (s) Air Intake Control Valves - Air intake control valves are elements of the intake system with variable geometry (ACIS). On V6 engines, ACIS improves torque throughout the entire operating range, especially in the low speed range, by changing the effective length of the intake manifold ducts (For more information about the ACIS system, see paragraph 15).
On models 1999-2003. with the V6 engine, the ACIS system uses two air intake control valves: one is installed inside the throttle body and the other is installed inside the air intake storage chamber. A vacuum actuated actuator activates each air intake control valve and a PCM-controlled vacuum switching valve (VSV) actuates each actuator.
On 2004 and later models with a V6 engine, the ACIS system is simplified with only one air intake control valve located on the air intake storage plenum. Like earlier units, it is activated by a vacuum actuated actuator, which in turn is actuated by a PCM-controlled vacuum switching valve (VSV).
29. Vacuum switching valve (VSV) for the pressure switching valve - The VSV valve for the pressure switching valve is part of the fuel vapor recovery system (EVAP) on models 1999-2003. It is located under the vehicle, in the EVAP canister, which is located behind the rear suspension cross member. On a warm day, the gasoline in the fuel tank constantly evaporates, releasing hydrocarbon vapors into the atmosphere. As these vapors build up inside the tank, the pressure builds up. When the pressure inside the tank begins to exceed atmospheric pressure, the PCM-controlled vacuum switching valve opens, allowing fuel vapor to flow to the EVAP canister, where it is stored until purged
30. Vapor pressure sensor - Vapor pressure sensor, which is an element of the fuel vapor recovery system (EVAP), monitors the pressure inside the fuel tank and sends a signal to the powertrain control module (RSM). When the pressure begins to exceed the high threshold, the PCM instructs the canister shutoff valve to transfer excess vapor to the EVAP canister. The vapor pressure sensor is located on top of the fuel tank.