Toyota Tundra 2005 Service - Repair - Maintenance page 3802

System Outline
The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission etc. An outline
of the engine control is given here.
1. Input Signals
(1) Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built-in thermistor with a resistance which
varies according to the engine coolant temp. The engine coolant temp. is input into TERMINAL THW of the engine
control module as a control signal.
(2) Intake air temp. signal circuit
The intake air temp. sensor is installed in the mass air flow meter and detects the intake air temp., which is input as a
control signal to TERMINAL THA of the engine control module.
(3) Oxygen sensor signal circuit
The oxygen density in the exhaust emission is detected and is input as a control signal from the heated oxygen sensors
to TERMINALS OX1B, OX2B of the engine control module.
(4) RPM signal circuit
The camshaft position is detected by the camshaft position sensor and is input into TERMINAL G2+ of the engine
control module as a control signal. Also, the engine RPM is detected by the crankshaft position sensor and the signal is
input into TERMINAL NE+ of the engine control module.
(5) Throttle position sensor signal circuit
The throttle position sensor detects the throttle valve opening angle as a control signal, which is input into TERMINALS
VTA1, VTA2 of the engine control module.
(6) Vehicle speed circuit
The vehicle speed sensor, detects the vehicle speed and input to the speed sensor of the skid control ECU with
actuator, from skid control ECU to TERMINAL SPD of the engine control module, via combination meter.
(7) Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine control module. When the ignition SW is turned on, the
voltage for engine control module start up power supply is applied through the EFI relay, to TERMINALS +B, +B2 of the
engine control module. The current from the IGN fuse flows to TERMINAL IGSW of the engine control module, and
voltage is constantly applied to TERMINAL +BM.
(8) Intake air volume signal circuit
The intake air volume is detected by the mass air flow meter, and is input as a control signal to TERMINAL VG of the
engine control module.
(9) Stop light SW signal circuit
The stop light SW is used to detect whether the vehicle is braking or not, and the signal is input into TERMINAL STP of
the engine control module as a control signal.
(10) Starter signal circuit
To confirm whether the engine is cranking, the voltage applied to the starter motor when the engine is cranking is
detected, and is input into TERMINAL STA of the engine control module as a control signal.
(11) Engine knock signal circuit
Engine knocking is detected by the knock sensors, and is input into TERMINALS KNK1, KNK2 of the engine control
module as a control signal.
2005 TOYOTA TUNDRA (EWD611U)
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