2002 Toyota Tacoma Idle Control System Malfunction Engine Diagnostics

The rotary solenoid type IAC valve is located in front of the intake air chamber and intake air bypassing the throttle valve is directed to the IAC valve through a passage. In this way, the intake air volume bypassing the throttle valve is regulated, controlling the engine speed. The ECM operates only the IAC valve to perform idle–up and provide feedback for the target idling speed.

2002 Toyota Tacoma System too Lean (Fuel Trim) Engine Diagnostics

Fuel trim is related to the feedback compensation value, not to the basic injection time. Fuel trim includes short–term fuel trim and long–term fuel trim. Short–term fuel trim is the short–term fuel compensation used to maintain the air–fuel ratio at its ideal theoretical value. The signal from the A/F sensor is approximately proportional to the existing air–fuel ratio, and ECM compares it with the ideal theoretical value, the ECM reduces fuel volume immediately if the air–fuel ratio is RICH and increases fuel volume if it is LEAN. Long–term fuel trim compensates for the deviation from the central value of the short–term fuel trim stored by each engine tolerance, and the deviation from the central value due to the passage of time and changes of environment. If both the short–term fuel trim and long–term fuel trim exceed a certain value, it is detected as a malfunction and the MIL lights up.

2002 Toyota Tacoma Knock Sensor 1 Circuit Malfunction

Each knock sensor is fitted to the right bank and left bank of the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to the knocking. If engine knocking occurs, ignition timing is retarded to suppress it.

2002 Toyota Tacoma Igniter Circuit Malfunction

A Direct Ignition System (DIS) has been adopted. The DIS improves the ignition timing accuracy, reduces high–voltage loss, and enhances the overall reliability of the ignition system by eliminating the distributor. The DIS is a 2–cylinder simultaneous ignition system which ignites 2 cylinders simultaneously with 1 ignition coil. In the 2–cylinder simultaneous ignition system, each of the 2 spark plugs is connected to the end of the secondary winding. High voltage generated in the secondary winding is applied directly to the spark plugs. The sparks of the 2 spark plugs pass simultaneously from the center electrode to the ground electrode. The ECM determines ignition timing end outputs the ignition signals (IGT) for each cylinder. Based on IGT signals, the igniter controls the primary ignition signals (IGC) for all ignition coils. At the same time, the igniter also sends an ignition confirmation signal (IGF) as a fail–safe measure to the ECM.

2002 Toyota Tacoma Crankshaft Position Sensor ”A” Circuit Malfunction Diagnostics

The crankshaft position sensor, which detects the engine speed and crankshaft angle signal (NE signal), has been installed on the oil pump body. The NE signal plate has 34 teeth. The NE signal sensor generates 34 signals at every engine revolution. The ECM detects the standard crankshaft angle based on the G signal, and the actual crankshaft angle and the engine speed by the NE signal.