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Home >> Suzuki >> 2003 >> Aerio S, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0112: Intake Air Temperature Sensor Circuit - Low Input >> Diagnosis & Repair Procedure

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 ON position. Using scan tool, observe IAT sensor values. If IAT sensor value is 401°F (205°C), go to next step. If IAT sensor value is not 401°F (205°C), problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO-CODES article. After repair, repeat DTC CONFIRMATION TEST .
  3. Turn ignition switch to LOCK position. Disconnect IAT sensor 2-pin harness connector C17. See Figure. Check IAT sensor and 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, turn ignition switch to ON position and measure voltage between ground and IAT sensor harness connector C17 terminal No. 2 (Light Green/Black wire). See Figure. If voltage is not 4-6 volts, go to next step. If voltage is 4-6 volts, go to step  6.
  4. Turn ignition switch to LOCK position. Disconnect ECM harness connector C46. See Figure. Measure resistance between ground and ECM harness connector C46 terminal No. 16 (Light Green/Black wire). See Figure. If resistance is infinity, go to next step. If any resistance is found, check Light Green/Black wire for short to ground or short to other circuits between ECM and IAT sensor. If short circuit is found, repair as necessary and repeat DTC CONFIRMATION TEST . If no short circuit is found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
  5. Turn ignition switch to ON position. Measure voltage between ground and ECM harness connector C46 terminal No. 16 (Light Green/Black wire). See Figure. If voltage is zero volt, go to next step. If any voltage is found, check Light Green/Black wire for short to other circuits between ECM and IAT sensor. If short circuit is found, repair as necessary and repeat DTC CONFIRMATION TEST . If short circuit is not found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
  6. Turn ignition switch to LOCK position. Perform IAT sensor component test. See INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If MAP sensor is faulty, replace IAT sensor. See INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST . If IAT sensor is okay, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST .
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