internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to these components in the
mass air flow meter sub-assembly. The voltage level is proportional to the air flow through the sensor, and the ECM uses it to calculate the intake air
volume.
The circuit is constructed so that the platinum hot wire and the temperature sensor create a bridge circuit, and the power transistor is controlled so
that the potentials of A and B remain equal to maintain the predetermined temperature.
HINT
When any of these DTCs are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the
ECM, according to the engine speed and throttle valve position. Fail-safe mode continues until a pass condition is detected.
HINT
When any of these DTCs are set, check the air flow rate by entering the following menus on the Techstream: Powertrain / Engine
/ Data List / MAF.
NOTICE:
- Perform the inspection with the vehicle indoors and on a level surface.
- Perform the inspection of the mass air flow meter sub-assembly while it is installed to the air cleaner case (installed to the
vehicle).
- During the test, do not use an exhaust air duct on the tail exhaust pipe assembly.
MONITOR DESCRIPTION
If there is a defect in the mass air flow meter sub-assembly or an open or short circuit, the voltage level deviates from the normal operating range.
The ECM interprets this deviation as a malfunction in the mass air flow meter sub-assembly and sets a DTC.
Example:
When the sensor output voltage remains less than 0.2 V, or more than 4.9 V, for more than 3 seconds, the ECM sets a DTC.
If the malfunction is not repaired successfully, a DTC is set 3 seconds after the engine is next started.
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