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Diagnosis & Repair Procedure

NOTE: For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
NOTE: Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
  1. If engine system check has been performed, go to next step. If engine system check has not been performed, perform TEST D: ENGINE SYSTEM CHECK  under SYSTEM TESTS then go to next step.
  2. Turn ignition switch to LOCK position. Check MAF sensor and air intake system for blockage. Also check for intake air system leaks. If no problem is found, go to next step. If problem is found, repair as necessary and repeat DTC CONFIRMATION TEST .
  3. Start engine and allow it to reach normal operating temperature. Using scan tool, read MAF sensor values at idle and at 2500 RPM. MAF sensor value should be 1.5-4.0 grams/second at idle speed and 5.0-10.0 grams/second at 2500 RPM. If MAF sensor values are not as specified, go to next step. If MAF sensor values are as specified, go to step  11.
  4. Turn ignition switch to LOCK position. Locate ECM harness connectors. See Figure. Turn ignition switch to ON position. Backprobe and measure voltage between ground and ECM harness connector C46 terminals No. 24 (Green wire) and No. 27 (Orange wire). See Figure. Voltage should be 0.5-1.0 volt. Start engine and allow it to idle, backprobe and measure voltage at same terminals. Voltage should now be 1.3-1.8 volts. If any voltage reading is not as specified, go to next step. If both voltage readings are as specified, check ECM harness connector terminals for corrosion or poor connection. If connector terminals are faulty, repair as necessary and repeat DTC CONFIRMATION TEST . If connector terminals are okay, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
  5. Turn ignition switch to LOCK position. Disconnect MAF sensor 4-pin harness connector C51 located on intake hose between air cleaner box and throttle body. See Figure. Turn ignition switch to ON position. Measure voltage between ground and MAF sensor harness connector C51 terminal No. 3 (Black/Red wire). See Fig 1. If voltage is 10-14 volts, go to next step. If voltage is less than 10 volts, repair open circuit in Black/Red wire between MAF sensor, main relay and ECM. After repair, repeat DTC CONFIRMATION TEST .
  6. Turn ignition switch to LOCK position. Measure resistance between ground and MAF sensor harness connector C51 terminal No. 2 (Orange wire). See Fig 1. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, go to step  8.
  7. Remove ECM and leave ECM harness connectors connected. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article. Backprobe and measure resistance between ground and ECM harness connector C46 terminals No. 27 (Orange wire). See Figure. If resistance is less than 5 ohms, repair open or short circuit in Orange wire between MAF sensor and ECM. If resistance is 5 ohms or more, check ECM ground circuits (Black/Orange wire) and (Black wire) for open or short between ECM and ground. If ground circuits are faulty, repair as necessary and repeat DTC CONFIRMATION TEST . If ground circuits are okay, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
  8. Turn ignition switch to ON position. Measure voltage between ground and MAF sensor harness connector C51 terminals No. 1 (Green Wire). See Fig 1. If voltage is zero volts, go to next step. If any voltage is found, repair short to voltage in Green wire between MAF sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .
  9. Turn ignition switch to LOCK position. Disconnect ECM harness connector C46. See Figure. Measure resistance between ground and MAF sensor harness connector C51 terminal No. 1 (Green wire). See Fig 1. If resistance is infinity, go to next step. If any resistance is found, repair short to ground in Green wire between MAF sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .
  10. Measure resistance between ECM harness connector C46 terminal No. 24 and MAF sensor harness connector C51 terminal No. 1 (Green wire). See Figure and Fig 1 . If resistance is less than 3 ohms, replace MAF sensor. See MASS AIR FLOW (MAF) SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. If resistance is more than 3 ohms, repair open or short circuit in Green wire between ECM and MAF sensor. After repair, repeat DTC CONFIRMATION TEST .
  11. Turn ignition switch To LOCK position. Locate ECM harness connectors. See Figure. Turn ignition switch to ON position. Backprobe and measure voltage between ground and ECM harness connector C45 terminal No. 7 (Light Green/Red wire) and ECM harness connector C46 terminal No. 27 (Orange wire). See Figure. Voltage should be 3.3-4.3 volts at 100 kPa of barometric pressure. Also measure voltage at same connectors with engine running at idle speed, voltage should be 0.7-1.6 volts at 100 kPa of barometric pressure. If voltage readings are as specified, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST . If voltage readings are not as specified, perform MAP sensor component test. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. After repair, repeat DTC CONFIRMATION TEST .
Fig 1: Identifying Mass Air Flow Sensor Harness Connector C51 Terminals
G00232456Courtesy of SUZUKI OF AMERICA CORP.
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