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Home >> Suzuki >> 2003 >> Aerio S, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0123: Throttle Position Sensor Circuit - High 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 throttle valve opening percentage displayed on scan tool from full close throttle valve to wide open throttle valve. If percentage displayed on scan tool is 100 percent, go to next step. If percentage displayed on scan tool is less than 100 percent, 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 TP sensor 3-pin harness connector C29. See Figure. Check TP 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. Measure voltage between ground and TP sensor harness connector C29 terminal No. 2 (Gray/Blue wire) and No. 3 (Gray/Red 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. Locate ECM. See Figure. Disconnect ECM harness connectors and check 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, reconnect ECM harness connectors and disconnect Manifold Absolute Pressure (MAP) sensor 3-pin harness connector. See Figure. Turn ignition switch to ON position. Backprobe and measure voltage between ground and ECM harness connector C46 terminal No. 18 (Gray/Red wire) and No. 25 (Gray/Blue wire). See Figure. If voltage is not 4-6 volts, go to next step. If voltage is 4-6 volts, check Gray/Red wire and Gray/Blue wire for open or short circuit between TP sensor and ECM. Also perform MAP sensor component test. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If TP sensor circuits and MAP sensor are okay, go to next step. If TP sensor circuits and/or MAP sensor are faulty, repair TP sensor circuits as necessary and/or replace MAP sensor. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST .
  5. Turn ignition switch to LOCK position. Disconnect ECM harness connector C46. Turn ignition switch to ON position. Measure voltage between ground and ECM harness connector C46 terminal No. 18 (Gray/Red wire) and No. 25 (Gray/Blue wire). See Figure. If voltage is zero volt, go to next step. If any voltage is found, check Gray/Red wire and Gray/Blue wire for short to voltage between TP sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .
  6. Turn ignition switch to LOCK position. Measure resistance between ECM harness connector C46 terminal No. 25 (Gray/Blue wire) and TP sensor harness connector C29 terminals No. 2 (Gray/Blue wire). See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or short circuit in Gray/Blue wire between TP sensor and ECM. After repair, repeat DTC CONFIRMATION TEST .
  7. Reconnect ECM harness connector and ensure proper terminal connection. Measure resistance between ground and MAP sensor harness connector C27 terminal No. 2 (Orange wire). See Figure. If resistance is 10 ohms or more, go to next step. If resistance is less than 10 ohms, go to step  9.
  8. Backprobe and measure resistance between ground and ECM harness connector C46 terminal No. 27 (Orange wire). See Figure. If resistance is less than 5 ohms, repair open or short circuit in Orange wire between MAP sensor, TP sensor and ECM. After repair, repeat DTC CONFIRMATION TEST . 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 .
  9. Check TP sensor by measuring resistance between TP sensor connector terminals (component side). See Figure. See THROTTLE POSITION SENSOR RESISTANCE  table. If resistances are as specified, go to next step. If any resistance is not as specified, replace TP sensor. See THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST .
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