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Home >> Suzuki >> 2003 >> XL-7 Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P1120: Throttle Position Sensor 1 - Circuit Malfunction >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Isuzu Trooper. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ON-BOARD DIAGNOSTIC II SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
  2. Perform ELECTRIC THROTTLE CONTROL SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing electronic throttle control system check, go to next step.
  3. Turn ignition on. Using scan tool, Observe MAP sensor parameter. If parameter is less than 65 kPa, go to next step. If parameter is not as specified, go to step  7.
    4. NOTE: If parameter does not read 5 volts, check 5-volt reference circuit for EGR valve and Fuel Vapor Pressure (FVP) sensor. See WIRING DIAGRAMS article.
  4. Disconnect MAP sensor 3-pin harness connector. MAP sensor is located at rear of intake manifold. Connect a fused jumper wire between MAP sensor harness connector terminals No. 2 (Red wire) and No. 3 (Red/Black wire). See Figure. On scan tool, observe MAP sensor voltage parameter. If MAP sensor voltage parameter is less than 5 volts, go to step  6. If MAP sensor voltage parameter is not as specified, go to next step.
  5. Check for open or short circuit in Red/Black wire (MAP sensor signal circuit) between PCM and MAP sensor. See WIRING DIAGRAMS article. If problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to step  13.
  6. Replace MAP sensor. See REMOVAL, OVERHAUL & INSTALLATION article. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  7. Start engine and run until normal operating temperature is achieved (minimum 176°F 80°C). Turn ignition on, engine off. Using scan tool, observe TPS1 angle while slowly opening throttle. TPS1 angle should increase steadily and smoothly from closed value (6-12 percent) to WOT value (79-83 percent). If TPS1 operates as specified, go to next step. If TPS1 does not operate as specified, go to step  9.
  8. Use scan tool to retrieve DTCs. If DTC P1120 was reset, go to step  13. If DTC P1120 was not reset, check for intermittent problem. See DIAGNOSTIC AIDS .
  9. Using DVOM, measure voltage between TPS harness connector terminals No. 1 (Green wire) and No. 5 (Red/Blue wire). See Fig 1. Voltage reading should be 5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step  11.
  10. Check for short to voltage in Red/Blue wire (TPS1 signal circuit) between TPS1 and PCM. Check for high resistance or poor connection in Green wire (TPS1 sensor ground) between TPS1 and PCM. See WIRING DIAGRAMS article. If problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  11. Check for high resistance or faulty connection in Red/Blue wire (TPS1 signal circuit) between TPS1 and PCM. Check for high resistance or faulty connection in Green wire (TPS1 ground circuit) between TPS1 and PCM. If problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  12. Replace TPS. See REMOVAL, OVERHAUL & INSTALLATION article. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  13. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE REPLACEMENT  under POWERTRAIN CONTROL MODULE. Use scan tool to clear DTC and verify repair.
Fig 1: Identifying Throttle Position Sensor Harness Connector Terminals
G00077236Courtesy of ISUZU MOTOR CO.
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