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Mass Air Flow MAF
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Mass Air Flow (MAF) Sensor Test Procedure
Testing is done on-vehicle.
Warning: This test involves running the engine. Observe all safety
precautions (see page ii). Work in well-ventilated area.
1) Verify ignition key is OFF.
2) Check Tester battery
Refer to page 1-4. Set RANGE switch to POWER
OFF when done.
3) Connect test leads - refer to hook-up diagram.
Keep sensor connected to vehicle wiring.
• YELLOW to sensor SIGNAL circuit. Use
backprobe adapter.
• BLACK to good vehicle GROUND.
4) Verify test clips make good contact.
Make sure unused clips are not touching any-
thing.
5) Set switches - refer to hook-up diagram.
6) Turn ignition key ON but DO NOT START
ENGINE.
7) Note TEST light position on tester.
• Typically, the TEST light will be off, at the
bottom of the column or blinking.
• Ignore any PULSE light action.
• If the sensor is good, the light will move upwards
during engine run.
8) Start engine and let idle - Watch TEST light for
results.
Good Sensor:
– TEST light moves upward after engine starts.
TEST light moves up even further if engine RPM
is momentarily increased. (Move throttle to
check.) Range of TEST light movement
varies with sensor type and engine speed.