Mass Air Flow Sensor, Checking
Mass Air Flow Sensor, Checking
Observe all safety precautions: => [ Safety Precautions ] Safety Precautions
View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions
Prior to repair work, perform a preliminary check to verify the condition. Refer to => [ Preliminary Check ] Preliminary Check.
• Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor (G70).
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• The Mass Air Flow (MAF) Sensor (G70) fuse 1 in Fuse Panel C is OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground connections between engine/transmission/chassis OK.
• Coolant Temperature at least 55° C.
• Ignition switched Off.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check
Start diagnosis
- Connect the scan tool.
- Start engine and let it run at idle.
- Using the scan tool, Check the air flow quantity of the Mass Air Flow (MAF) Sensor (G70) at idle:
If the specified value was obtained: Condition is not present at this time.
- Check the electrical harness connector at the ECM and sensor for damage, corrosion, loose or broken terminals.
- Check the intake duct for air leaks, loose connections.
If the specified value was Not obtained:
Checking voltage supply
- Disconnect the Mass Air Flow (MAF) Sensor (G70) electrical harness connector.
- Start the engine and let it run at idle.
- Using a multimeter, check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminal 5 to engine Ground for voltage.
Specified value: Battery voltage.
- Switch the ignition OFF.
If the specified value was Not obtained:
- Remove fuse 1 (2010 Models) or fuse 15 (2011 Models) in Fuse Panel C. Refer to Wiring Diagrams for fuse locations. Check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminal 5 to Fuse 1 or 15 in Fuse Panel C for an open circuit, high resistance or short to ground.
Specified value: 1.5 ohms max.
- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
Checking electrical circuit
- Start the engine and let it run at idle.
- Using a multimeter, connect black lead to ground and red lead to terminal 1, 2 and 4 of the MAF connector and check for voltage using the chart below.
Specified values:
- Switch the ignition OFF.
If the specified value was Not obtained:
Checking wiring
- Remove the Engine Control Module (ECM) (J623). Refer to the Repair Information.
- Using a multimeter, check the Mass Air Flow (MAF) Sensor (G70) electrical harness connector terminals to the Engine Control Module (ECM) (J623) electrical harness connector T94 terminals for an open circuit. Refer to Wiring Diagrams for Pin locations.
Specified value: 1.5 ohms max.
If the specified value was Not obtained:
- Check the wiring for an open, high resistance or short circuit.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring and the voltage supply was OK:
- Replace Mass Air Flow (MAF) Sensor (G70) Refer to the Repair Information.
If no malfunction is detected in the wiring and the voltage supply was Not OK:
- Replace the Engine Control Module (ECM) (J623). Refer to the Repair Information.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.