Mass Airflow Sensor - G70-, Checking

General Description

The signal from the Mass Airflow Sensor -G70- is used in the Engine Control Module -J623- to calculate the volumetric efficiency. Based on the volumetric efficiency, and taking into consideration the lambda value and ignition timing, the Engine Control Module -J623- calculates the engine torque.

Special tools and workshop equipment required

Multimeter.
Wiring Diagram.
Scan Tool.

Test requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2. -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. CONNECT: Scan tool. start : Engine and let Idle. CHECK: The air flow quantity of the Mass Air Flow Sensor -G70-. SPECIFIED VALUE: About 2.0 to 5.0 g/s. IGNITION: OFF. -- Was Value obtained?	-- YES: Condition may be intermittent. PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5. -- NO: GO TO: Step 3.
3	DISCONNECT: Mass Airflow Sensor -G70- harness connector. IGNITION: ON. CHECK: Mass Airflow Sensor -G70- harness connector terminal 3 to ground for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- Was Value obtained?	-- YES: GO TO: Step 4. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5.
4	REMOVE: Engine Control Module - J623-. Refer to appropriate Service Information. CHECK: Mass Airflow Sensor -G70- harness connector terminal 1 to the Engine Control Module - J623- harness connector T105 / 104 for resistance. CHECK: Mass Airflow Sensor -G70- harness connector terminals 2 to the Engine Control Module - J623- harness connector terminals T105 / 82 for resistance. CHECK: Mass Airflow Sensor -G70- harness connector terminals 3 to the Engine Control Module - J623- harness connector terminals T91 / 50 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Mass Airflow Sensor -G70-. Refer to appropriate Service Information. GO TO: Step 5. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5.
5	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate Service Information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return, the repair is complete. Return vehicle to customer.