With Generic Scan Tool

COMPONENT DESCRIPTION
The mass air flow sensor is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot film that is supplied with electric current from the ECM. The temperature of the hot film is controlled by the ECM a certain amount. The heat generated by the hot wire is reduced as the intake air flows around it. The more air, the greater the heat loss.

Therefore, the ECM must supply more electric current to the hot film as air flow increases. This maintains the temperature of the hot film. The ECM detects the air flow by means of this current change.






CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Specification data are reference values.






ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values, and are measured between each terminal and (25) (ECCS ground).






FAIL-SAFE MODE
When the ECM enters the fail-sate mode, the MIL illuminates.






ON BOARD DIAGNOSIS LOGIC



DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
Perform "Procedure for malfunction A" first. If the 1st trip DTC cannot be confirmed, perform "Procedure for malfunction B". if there is no problem on "Procedure for malfunction B", perform "Procedure for malfunction C". if there is no problem on "Procedure for malfunction C", perform "Procedure for malfunction D".

CAUTION: Always drive vehicle at a safe speed.

NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.

Procedure for malfunction A

With Generic Scan Tool
(1) Turn ignition switch "ON", and wait at least 6 seconds.
(2) Select "MODE 7" with GST.


Procedure for malfunction B


With Generic Scan Tool
(1) Turn ignition switch "ON".
(2) Start engine and wait for 5 seconds at most.
(3) Select "MODE 7" with GST.


NOTE: If 1st trip DTC is confirmed after more than 5 seconds, there may be malfunction C.


Procedure for malfunction C


With Generic Scan Tool
(1) Start engine and warm it up to normal operating temperature.
(2) Run engine for at least 10 seconds at idle speed.
(3) Select "MODE 7" with GST.



OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the mass air flow sensor circuit. During this check, a 1st trip DTC might not be confirmed.

Procedure for malfunction D






With Generic Scan Tool
(1) Turn ignition switch "ON".
(2) Start engine and warm it up to normal operating temperature.
(3) Select "MODE 1" with GST.
(4) Check the mass air flow with "MODE 1".
(5) Check for linear mass air flow rise in response to increases to about 4,000 rpm in engine speed.











Wiring & Terminal Diagram






Diagnostic Procedure


COMPONENT INSPECTION












Mass air flow sensor
1. Turn ignition switch "ON".
2. Start engine and warm it up to normal operating temperature.
3. Check voltage between ECM terminal (54) and ECM terminal (26) (ECM ground).
4. If the voltage is out of specification, disconnect mass air flow sensor harness connector and connect it again. Repeat above check.
5. If NG, remove mass air flow sensor from air duct. Check hot film for damage or dust.