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Home >> Mazda >> 2007 >> B4000 SE, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (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 B4000, 2003 Mazda B3000, and 2003 Mazda B2300. 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  3 .
    • For DTC P0123, go to step  8 .
    • For Continuous Memory DTC P1124, go to step  8 .
    • For DTC P0122, go to step  12 .
    • For DTC P1121, go to step  16 .
    • For DTC P1125, go to step  20 .
    • For DTC P0121, go to step  22 .
  2. 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  8 . If throttle does not move freely and does not return to closed throttle position, repair or replace as necessary. After repair, go to step  24 .
  3. DTC P1120: Check TP Circuit For Frayed Wires Or Corrosion On Connectors -  Visually inspect TP sensor 3-pin harness connector pins for corrosion. Visually inspect harness wires 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  24 .
  4. Check For Stuck TP Sensor -  With KOEO, access TP V PID. Slowly move throttle from closed throttle position to Wide Open Throttle (WOT) position and observe TP V PID. If voltage reading is less than 0.49 volt, go to next step. If voltage reading is 0.49 volt or more, go to step  20 .
  5. Check VREF & SIG RTN Circuit To TP Sensor -  Turn ignition off. Disconnect TP sensor 3-pin harness connector. With KOEO, measure voltage between VREF circuit (Brown/White wire) and SIG RTN circuit (Gray/Red wire) at TP sensor 3-pin harness connector. See Fig 1 . If voltage reading is 4-6 volts, go to next step. If voltage reading is not 4-6 volts, restore all electrical connections. Go to VEHICLE REFERENCE VOLTAGE  testing under SYSTEM TESTS.
    Fig 1: Identifying TP Sensor Circuits
    G00155530Courtesy of MAZDA MOTORS CORP.
  6. Check TP Circuit Resistance -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect breakout box 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 (Gray/White wire). See Fig 1 . If resistance reading is less than 5 ohms, go to next step. If resistance reading is 5 ohms or more, repair open circuit. After repair, go to step  24 .
  7. Check TP Sensor Signal To PCM -  Connect PCM to breakout box harness connector. 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. If voltage reading is 0.17-0.49 volt at any time, replace faulty TP sensor. After repair, go to step  24 . If voltage reading is not 0.17-0.49 volt at any time, rerun KOEO and KOER test. If DTC P1120 is still present, go to step  20 .
  8. DTCs P0123 Or P0124: Attempt To Generate The Opposite Throttle Position Angle (Voltage) PID Reading -  An intermittent may cause DTC P0123. If DTC P0123 is still set after performing steps  8 - 11 , go to step  20 . If DTC P0123 is not set after performing steps  8 - 11 , turn ignition off. Disconnect TP sensor 3-pin harness connector. With KOEO, access TP V PID. Observe voltage. If voltage reading is less than 0.17 volt, go to next step. If voltage reading is 0.17 volt or more, go to step  11 .
  9. Check SIG RTN Circuit For Open -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect breakout box to PCM harness connector only. See Figure . Measure resistance of SIG RTN circuit (Gray/Red wire) between breakout box terminal No. 91 and TP sensor 3-pin harness connector. See Fig 1 . If resistance reading is less than 5 ohms, go to next step. If resistance reading is 5 ohms or more, repair open circuit in Gray/Red wire between PCM 104-pin harness connector terminal No. 91 and TP sensor 3-pin harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  24 .
  10. Check VREF & SIG RTN Circuits To TP Sensor -  With KOEO, measure voltage between VREF circuit (Brown/White wire) and SIG RTN circuit (Gray/Red wire) at TP sensor 3-pin harness connector. See Fig 1 . If voltage reading is 4-6 volts, replace faulty TP sensor. After repair, go to step  24 . If voltage reading is not 4-6 volts, restore all electrical connections. Go to VEHICLE REFERENCE VOLTAGE  testing under SYSTEM TESTS.
  11. Check TP Circuit For Shorts To VREF Or VPWR In Harness -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect breakout box to PCM harness connector only. See Figure . Measure resistance between breakout box terminal No. 89 (TP circuit) and terminals No. 71 or 97 (VPWR circuit). Record reading. Measure resistance between breakout box terminals No. 89 (TP circuit) and 90 (VREF circuit). Record reading. If either resistance reading is more than 10,000 ohms, replace faulty PCM. After repair, go to step  24 . If either resistance reading is 10,000 ohms or less, repair short circuit in harness. After repair, go to step  24 .
  12. DTC P0122: Attempt To Generate The Opposite Throttle Position Angle (Voltage) PID Reading -  An intermittent fault may cause Continuous Memory DTC P0122. If DTC P0122 is still set after performing steps  12 - 15 , go to step  20 . Turn ignition off. Disconnect TP sensor 3-pin harness connector. Connector fused jumper wire between VREF circuit (Brown/White wire) and TP circuit (Gray/White wire) at TP sensor 3-pin harness connector. See Fig 1 . With KOEO, access TP V PID. If a scan tool communication concern is present, remove fuse jumper wire and go to step  15 . If voltage reading is more than 4.65 volts, replace faulty TP sensor. After repair, go to step  24 . If voltage reading is 4.65 volts or less, remove fused jumper wire and go to next step.
  13. Check VREF & SIG RTN Circuits To TP Sensor -  With KOEO, measure voltage between VREF circuit (Brown/White wire) and SIG RTN circuit (Gray/Red wire) at TP sensor 3-pin harness connector. See Fig 1 . If voltage reading is 4-6 volts, go to next step. If voltage reading is not 4-6 volts, restore all electrical connections. Go to VEHICLE REFERENCE VOLTAGE  testing under SYSTEM TESTS.
  14. Check For Open TP Circuit Between PCM & TP Sensor -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect breakout box to PCM harness connector only. See Figure . Measure resistance of TP circuit (Gray/White wire) between breakout box terminal No. 89 and TP sensor 3-pin harness connector. See Fig 1 . If resistance reading is less than 5 ohms, go to next step. If resistance reading is 5 ohms or more, repair open circuit in Gray/White wire between PCM 104-pin harness connector terminal No. 89 and TP sensor 3-pin harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  24 .
  15. Check TP Circuit For Shorts To SIG RTN Or PWR GND In Harness -  Turn ignition off. Disconnect scan tool. Measure resistance between breakout box terminal No. 89 (TP circuit) and breakout box terminals No. 51 and 103 (PWR GND circuit). Record reading. Measure resistance between breakout box terminals No. 89 (TP circuit) and 91 (SIG RTN circuit). Record reading. If either resistance reading is more than 10,000 ohms, replace faulty PCM. After repair, go to step  24 . If either resistance reading is 10,000 ohms or less, repair short circuit in harness. After repair, go to step  24 .
  16. DTC P1121: TP Sensor & MAF 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 discrepancies are found, go to NO START  testing under SYSTEM TESTS.
  17. Check Mechanical Operation Of TP Sensor -  With KOEO, access TP V PID. Slowly open throttle from closed throttle position to Wide Open Throttle (WOT) position. While observing TP V PID, slowly open throttle. If voltage reading changed between 0.49-4.65 volts, go to next step. If voltage reading does not change between 0.49-4.65 volts, replace faulty TP sensor. After repair, go to step  24 .
  18. Check TP Sensor Signal High Vs. Engine Load While Driving -  Drive vehicle exercising throttle. Observe TP V PID and LOAD PID. Record readings. If TP V PID is not more than 2.44 volts and LOAD PID is not less than 30 percent, 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, repair as necessary. If air leaks are not present, replace faulty TP sensor. After repair, go to step  24 .
  19. Check TP Sensor Signal Low Vs. Engine Load While Driving -  Drive vehicle exercising throttle. Observe TP V PID and LOAD PID. 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  24 . If TP V PID reading is less than 0.24 volt and LOAD PID 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  24 .
  20. 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 while lightly tapping on TP sensor and wiggling harness to simulate road shock. If voltage 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 changed to less than a minimum of 0.49 volt or more than a maximum of 4.65 volts, inspect TP sensor connector. If connector is okay, replace faulty TP sensor. Go to step  24 .
  21. Check TP Sensor Harness For Intermittent Opens & Shorts -  Access and observe TP V PID. With KOEO, 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  24 . 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  24 .
  22. Attempt To Re-Create DTC Or Driveability Symptom -  If KOER self-test terminates when placing transmission in Drive or Reverse, go to step  23 . 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 set or if KOER self-test fails to terminate, go to next step. If DTC P0121 is not set or if KOER self-test terminates, verify symptom is no longer present. Go to step  24 .
  23. 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 to PCM harness connector only. See Figure . Measure resistance of TP circuit (Gray/White wire) between breakout box terminal No. 89 and TP sensor 3-pin harness connector. Record reading. Measure resistance of SIG RTN circuit (Gray/Red wire) between breakout box terminal No. 91 and TP sensor 3-pin harness connector. See Fig 1 . Record reading. If either resistance reading is less than 5 ohms, replace faulty TP sensor. After repair, go to step  24 . If either resistance reading is 5 ohms or more, repair open circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  24 .
  24. Verify Trouble Shooting Of DTCs Completed -  Make sure all electrical connectors are reconnected. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If the same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTCs are present, test is complete.
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