Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMERCURY2010MARINER HYBRID, AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1377 (ENGINE CONTROLS - PINPOINT TESTS (HYBRID))PINPOINT TEST DC: MASS AIR FLOW (MAF) SENSORINTRODUCTION
2010 Mercury Mariner Hybrid, AWD
Pinpoint Test DC: Mass Air Flow (MAF) Sensor: Introduction
2010 Mercury Mariner Hybrid, AWDSECTION Introduction
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, 2011 Ford Fusion, 2010 Mercury Milan, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
WARNING:
TO PREVENT THE RISK OF HIGH-VOLTAGE SHOCK, ALWAYS FOLLOW PRECISELY ALL WARNINGS AND SERVICE INSTRUCTIONS, INCLUDING INSTRUCTIONS TO DEPOWER THE SYSTEM. THE HIGH-VOLTAGE HYBRID SYSTEM UTILIZES APPROXIMATELY 300 VOLTS DC, PROVIDED THROUGH HIGH-VOLTAGE CABLES TO ITS COMPONENTS AND MODULES. THE HIGH-VOLTAGE CABLES AND WIRING ARE IDENTIFIED BY ORANGE HARNESS TAPE OR ORANGE WIRE COVERING. ALL HIGH-VOLTAGE COMPONENTS ARE MARKED WITH HIGH-VOLTAGE WARNING LABELS WITH A HIGH-VOLTAGE SYMBOL. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN SERIOUS PERSONAL INJURY OR DEATH.
This pinpoint test is intended to diagnose the following:
- MAF sensor (12B579)
- harness circuits: MAF, MAF RTN, vehicle power (VPWR), power ground (PWRGND), IAT, and SIGRTN
- powertrain control module (PCM) (12A650)
MAF/IAT SENSOR CONNECTOR PINS REFERENCE CHART
| Pin | Circuit |
|---|---|
| 1 | IAT (Intake Air Temperature) |
| 2 | SIGRTN (Signal Return) |
| 4 | MAF RTN (Mass Air Flow Return) |
| 3 | MAF (Mass Air Flow) |
| 5 | PWRGND (Power Ground) |
| 6 | VPWR (Vehicle Power) |
PCM CONNECTOR PINS REFERENCE CHART
| Pin | Circuit |
|---|---|
| B40 | MAF (Mass Air Flow) |
| B41 | MAF RTN (Mass Air Flow Return) |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.