Circuit Description
The mass air flow meter uses a platinum hot wire. The hot wire air flow meter consists of a platinum hot wire, temperature sensor and a control circuit installed in a plastic housing. The hot wire air flow meter works on the principle that the hot wire and temperature sensor located in the intake air bypass of the housing detect any changes in the intake air temperature.
The hot wire is maintained at the set temperature by controlling the current flow through the hot wire. This current flow is then measured as the output voltage of the air flow meter.
The circuit is constructed so that the platinum hot wire and temperature sensor provide a bridge circuit with the power transistor controlled so that the potential of A and B remains equal to maintain the set temperature.
If the ECM detects DTC P0100 it operates the fail-safe function, keeping the ignition timing and injection volume constantly and making it possible to drive the vehicle.
HINT:
After confirming DTC P0100, use the OBD II scan tool or hand-held tester to confirm the mass air flow ratio from the CURRENT DATA.