Understanding Mass Air Flow (MAF) sensor wiring diagrams requires familiarity with standard automotive electrical symbols. Here's a breakdown of common symbols and abbreviations found on MAF wiring diagrams:
Power Supply & Ground Symbols
- B+ or VBAT: Battery positive voltage (typically 12V). Powers the MAF sensor heater (if present) and/or electronics.
- IGN: Ignition-switched positive voltage (12V when key is on). Powers the sensor electronics.
- Ground Symbol (⬇ or ⏚): Standard chassis or battery negative ground.
- GND: General ground connection point.
- SGND (Signal GND) or REF RTN: Dedicated sensor signal return path. Critical for accurate signal measurement.
MAF Signal Output Symbols
- MAF SIG or SIG: The main MAF sensor signal output wire.
- Analog Signal Symbol (~ or sine wave): Indicates a varying analog voltage output signal (commonly 0-5V or 0.5-4.5V depending on airflow).
- Digital Signal Symbol (□ containing waveform or 0101): Indicates a digital output signal (Frequency or Pulse Width Modulated).
- Hz: Specifies the output signal is frequency-based.
Reference Voltage & Control Symbols
- VREF (5V Ref): Stable 5-volt reference voltage supplied to the sensor by the Powertrain Control Module (PCM). Powers internal electronics.
- IMA / MAF RTN: Intake Air Temperature (IAT) sensor signal return (often shares MAF connector/housing).
- MAF HTR + / -: MAF sensor heating element power (+) and ground (-) wires (common on hot-wire types).
Connector Symbols
- : Representing an electrical connector. Letters/numbers inside often denote cavity/pin positions (e.g., A, B, C or 1, 2, 3, 4, 5).
- C101:32: Denotes connector number (C101), specific cavity/pin (32).
Key Diagram Conventions
- Wires are labeled with their function abbreviation (MAF SIG, VREF, GND) and often their wire color code (e.g., YEL/BLK).
- Arrows indicate direction of current flow or signal path.
- Boxes contain component names (e.g., MAF Sensor, PCM/ECM).
- Lines converging at a dot represent an electrical junction/splice.
Always consult the specific vehicle's service manual wiring diagram for precise wire colors, connector locations, and component designations.