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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0121, DTC P0122, DTC P0123, DTC P1120, DTC P1121, DTC P1124 Or DTC P1125 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed:
    • For KOEO and KOER DTC P1124, go to next step.
    • For DTC P1120, go to step  4.
    • For DTC P0123, go to step  9.
    • For Continuous Memory DTC P1124, go to step  9.
    • For DTC P0122, go to step  13.
    • For DTC P1121, go to step  17.
    • For DTC P1125, go to step  21.
    • For DTC P0121, go to step  23.
  2. Check For DTC P1400 In KOEO Or KOER Self-Test -  If KOEO or KOER DTC P1400 is present with P1124, go to DTC P1400 OR P1401: DIFFERENTIAL PRESSURE FEEDBACK SENSOR - MALFUNCTION . If KOEO or KOER DTC P1400 is not set with P1124, go to next step.
  3. Check For Stuck Throttle Plate Or Linkage -  Visually inspect throttle linkage and throttle plate for binding or sticking. Verify throttle plate and linkage is at closed throttle position. If throttle moves freely and returns to closed throttle position, go to step  9. If throttle does not move freely and does not return to closed throttle position, repair or replace as necessary. After repair, go to step  25.
  4. DTC P1120: Check TP Circuit For Frayed Wires Or Corrosion On Connectors -  Visually inspect TP sensor harness connector terminals for corrosion. Visually inspect wire harness between TP sensor 3-pin harness connector and PCM 104-pin harness connector for insulation fraying and corrosion. If connector and harness are okay, go to next step. If connector and harness are not okay, repair as necessary. After repair, go to step  25.
  5. Check For Stuck TP Sensor -  Turn ignition on, engine off. Access TP V PID. Slowly move throttle from closed throttle position to Wide Open Throttle (WOT) position and observe TP V PID. If TP V PID voltage reading is less than 0.49 volt, go to next step. If TP V PID voltage reading is 0.49 volt or more, go to step  21.
  6. Check VREF & SIG RTN Circuit To TP Sensor -  Turn ignition off. Disconnect TP sensor 3-pin harness connector. Turn ignition on, engine off. Measure voltage between TP sensor 3-pin harness connector VREF terminal (Brown/White wire) and SIG RTN terminal (Orange wire). See Fig 1. If voltage reading is 4-6 volts, go to next step. If voltage reading is not as specified, reconnect all electrical connections. Go to VEHICLE REFERENCE VOLTAGE  testing under SYSTEM TESTS.
    Fig 1: Identifying Throttle Position (TP) Sensor Circuits & 3-Pin Harness Connector Terminals
    G99J02598Courtesy of FORD MOTOR CO.
  7. Check TP Circuit Resistance -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Measure resistance of Gray/White wire between TP sensor 3-pin harness connector and breakout box terminal No. 89. See Fig 1. If resistance reading is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit in Gray/White wire between TP sensor 3-pin harness connector terminal and PCM 104-pin harness connector terminal No. 89 through common connector. After repair, go to step  19.
  8. Check TP Sensor Signal To PCM -  Connect PCM to breakout box. Reconnect TP sensor 3-pin harness connector. Start engine and idle for 2 minutes. Access TP V PID. While observing TP V PID, slowly open throttle from closed position. If TP V PID reading is 0.17-0.49 volt at any time, replace faulty TP sensor. After repair, go to step  25. If TP V PID reading is not as specified, rerun KOEO and KOER test. If DTC P1120 is still present, go to step  21.
    9. NOTE: An intermittent fault may cause DTC P0123. If DTC P0123 is still set after performing steps  9- 12 , go to step  21.
  9. DTC P0123 Or DTC P0124: Attempt To Generate The Opposite Throttle Position Angle (Voltage) PID Reading -  Turn ignition off. Disconnect TP sensor 3-pin harness connector. Turn ignition on, engine off. Using scan tool, access TP V PID. If TP V PID reading is less than 0.17 volt, go to next step. If TP V PID reading is 0.17 volt or more, go to step  12.
  10. Check SIG RTN Circuit For Open -  Turn ignition off. Disconnect breakout box from PCM, leave PCM 104-pin harness connector connected. Measure resistance of SIG RTN circuit (Orange wire) between TP sensor 3-pin harness connector and breakout box terminal No. 91. See Fig 1. If resistance reading is less than 5 ohms, go to next step. If resistance reading is not as specified, repair open circuit in Orange wire between TP sensor 3-pin harness connector terminal and PCM 104-pin harness connector terminal No. 91 through common connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  25.
  11. Check VREF & SIG RTN Circuits To TP Sensor -  Turn ignition on, engine off. Measure voltage between TP sensor 3-pin harness connector VREF terminal (Brown/White wire) and SIG RTN terminal (Orange wire). See Fig 1. If voltage reading is 4-6 volts, replace faulty TP sensor. After repair, go to step  25. If voltage is not 4-6 volts, reconnect all electrical connections. Go to VEHICLE REFERENCE VOLTAGE  under SYSTEM TESTS.
  12. Check TP Circuit For Shorts To VREF Or VPWR In Harness -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Measure resistance between breakout box terminal No. 89 (TP) and terminal No. 71 or 97 (VPWR). Record reading. Measure resistance between breakout box terminals No. 89 (TP) and 90 (VREF). Record reading. If both resistance readings are more than 10,000 ohms, replace faulty PCM. After repair, go to step  25. If both resistance readings are not more than 10,000 ohms, repair short circuit in harness. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  25.
    13. NOTE: An intermittent fault may cause Continuous Memory DTC P0122. If DTC P0122 is still set after performing steps  13- 16 , go to step  21.
  13. DTC P0122: Attempt To Generate Opposite Throttle Position Angle (Voltage) PID Reading -  Turn ignition off. Disconnect TP sensor 3-pin harness connector. Connect fused jumper wire between TP sensor 3-pin harness connector VREF terminal (Brown/White wire) and TP terminal (Gray/White wire). See Fig 1. Turn ignition on, engine off. Access TP V PID. If a scan tool communication problems are present, remove jumper wire. Go to step  16. If TP V PID reading is more than 4.65 volts, replace faulty TP sensor. After repair, go to step  25. If TP V PID reading is not as specified, remove fused jumper wire. Go to next step.
  14. Check VREF & SIG RTN Circuits To TP Sensor -  Turn ignition on, engine off. Measure voltage between TP sensor 3-pin harness connector VREF terminal (Brown/White wire) and SIG RTN terminal (Orange wire). See Fig 1. If voltage reading is 4-6 volts, go to next step. If voltage reading is not as specified, restore vehicle to original condition. Go to VEHICLE REFERENCE VOLTAGE  testing under SYSTEM TESTS.
  15. Check For Open TP Circuit Between PCM & TP Sensor -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Measure resistance of TP circuit (Gray/White wire) between TP sensor 3-pin harness connector terminal and breakout box terminal No. 89. See Fig 1. If resistance reading is less than 5 ohms, go to next step. If resistance reading is not as specified, repair open circuit in Gray/White wire between TP sensor 3-pin harness connector terminal and PCM 104-pin harness connector terminal No. 89 through common connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  25.
  16. Check TP Circuit For Shorts To SIG RTN Or PWR GND In Harness -  Disconnect scan tool. Measure resistance between breakout box terminal No. 89 (TP) and terminals No. 51 and 103 (PWR GND). Record reading. Measure resistance between breakout box terminals No. 89 (TP) and 91 (SIG RTN). Record reading. If both resistance readings are more than 10,000 ohms, replace faulty PCM. After repair, go to step  25. If either resistance reading is not as specified, repair short circuit in harness. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  25.
  17. DTC P1121: TP Sensor & MAF/IAT Sensor Rationality Check -  Attempt to start engine. If engine runs, go to next step. If engine does not run, check for major leaks and cracks between MAF/IAT sensor and throttle body. Repair as necessary. If no problems are found, go to NO START  testing under SYSTEM TESTS.
  18. Check Mechanical Operation Of TP Sensor -  Turn ignition on, engine off. Using scan tool, access TP V PID. While observing TP V PID, slowly open throttle from closed throttle position to Wide Open Throttle (WOT) position. If TP V PID reading changes between 0.49 and 4.65 volts, go to next step. If TP V PID reading does not change as specified, replace faulty TP sensor. After repair, go to step  25.
  19. Check TP Sensor Signal High Versus Engine Load While Driving Vehicle -  Drive vehicle exercising throttle. Observe TP V and LOAD PIDs. Record readings. If TP V PID reading is 2.44 volts or less and LOAD PID reading is 30 percent or more, go to next step. If TP V PID is more than 2.44 volts and LOAD PID is less than 30 percent, check for air leaks between MAF/IAT sensor and throttle body while engine is running. If air leaks are present (including air noise sounds), repair as necessary. If air leaks or noises are not present, replace faulty TP sensor. After repair, go to step  25.
  20. Check TP Sensor Signal Low Versus Engine Load While Driving Vehicle -  Drive vehicle exercising throttle near higher gears (preferably overdrive). Access TP V and LOAD PIDs and record readings. If TP V PID reading is not less than 0.24 volt and LOAD PID is not more than 55 percent, fault is unable to be duplicated at this time. Go to step  25. If TP V PID reading is less than 0.24 volt and LOAD PID reading is more than 55 percent, verify TP sensor is securely attached to throttle body. Repair as necessary. If Continuous Memory DTC P1121 is not set, replace faulty MAF/IAT sensor. After repair, go to step  25.
  21. Check For TP Circuit Intermittent Voltage Input -  Start engine and idle. Increase engine speed to 1500 RPM for 5 seconds. Access TP V PID. Observe TP V PID reading for a fault indication while lightly tapping on TP sensor and wiggling harness to simulate road shock. If voltage reading did not change to less than a minimum of 0.49 volt or more than a maximum of 4.65 volts, go to next step. If voltage reading changed to less than a minimum of 0.49 volt or more than a maximum of 4.65 volts, inspect TP sensor 3-pin harness connector. If connector is okay, replace faulty TP sensor. After repair, go to step  25.
  22. Check TP Sensor Harness For Intermittent Opens & Shorts -  Access and observe TP V PID. Turn ignition on, engine off. Grasp harness nearest to TP sensor connector. Shake and bend a small section of wiring harness following harness to dash panel. Shake and bend harness from dash panel to PCM. If voltage reading did not change to less than a minimum of 0.49 volt or more than a maximum of 4.65 volts, fault is unable to be duplicated at this time. Go to step  25. If voltage reading changed to less than a minimum of 0.49 volt or more than a maximum of 4.65 volts, isolate fault in harness and repair as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  25.
    23. NOTE: If KOER self-test terminates when placing transaxle in Drive or Reverse, go to step  24.
  23. Attempt To Re-Create DTC Or Driveability Symptom -  Attempt to drive vehicle while still in KOER self-test. Turn ignition off. Wait 15 seconds. Start engine again. Activate KOER self-test. If DTC P0121 is still present or if KOER self-test again fails to terminate, go to next step. If DTC P0121 is not present or if KOER self-test terminates, verify symptom is no longer present. Go to step  25.
  24. Check TP Or SIG RTN Circuits For Open In Harness -  Turn ignition off. Disconnect PCM 104-pin harness connector and TP sensor 3-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Measure resistance of TP circuit between breakout box terminal No. 89 and TP sensor 3-pin harness connector terminal (Gray/White wire). Record reading. Measure resistance of SIG RTN circuit between breakout box terminal No. 91 and TP sensor 3-pin harness connector terminal (Orange wire). See Fig 1. Record reading. If both resistance readings are less than 5 ohms, repair open circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step. If both resistance readings are not as specified, replace faulty TP sensor. After repair, go to step  25.
  25. Verify Trouble Shooting Of DTCs Completed -  Reconnect all disconnected connectors. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is not present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, procedure is complete.
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