Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
- If QUICK TEST was not performed, go to QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed:
- Check For DTC P1400 In KOEO Or KOER Self-Test
If KOEO or KOER DTC P1400 is set 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. - 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. - 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. - 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. - Check VREF & SIG RTN Circuit To TP Sensor
Turn ignition off. Disconnect TP sensor. Turn ignition on, engine off. Measure voltage between 3-pin harness connector VREF terminal (Brown/White wire) and SIG RTN terminal (Orange wire). See Fig 1. If voltage is 4.0-6.0 volts, go to next step. If voltage is not as specified, reconnect all electrical connections. Go to VEHICLE REFERENCE VOLTAGE testing under SYSTEM TESTS . - 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 in Gray/White wire between TP sensor 3-pin harness connector terminal and PCM 104-pin harness connector terminal No. 38. After repair, go to step 25. - 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. 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 0.17-0.49 volt at any time, rerun KOEO and KOER test. If DTC P1120 is still present, go to step 21. - DTC P0123 Or DTC 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 9 through 12 , go to step 21. If DTC P0123 is not set after performing steps 9 through 12 , turn ignition off. Disconnect TP sensor 3-pin harness connector. Turn ignition on, engine off. Access TP V PID. Observe voltage. 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. - Check SIG RTN Circuit For Open
Turn ignition off.Disconnect PCM 104-pin harness connector. Disconnect breakout box from PCM. 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 is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Orange wire between TP sensor 3-pin harness connector terminal and PCM 104-pin harness connector terminal No. 91. See WIRING DIAGRAMS article. After repair, go to step 25. - 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 4.0-6.0 volts, replace faulty TP sensor. After repair, go to step 25. If voltage is not 4.0-6.0 volts, reconnect all electrical connections. Go to VEHICLE REFERENCE VOLTAGE under SYSTEM TESTS . - 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 either resistance measurement is more than 10,000 ohms, replace faulty PCM. After repair, go to step 25. If either resistance measurement is 10,000 ohms or less, repair short circuit in harness. See WIRING DIAGRAMS article. After repair, go to step 25. - DTC P0122: Attempt To Generate 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 13 through 16 , go to step 21. 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 concerns 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 4.65 volts or less, remove fused jumper wire. Go to next step. - 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 is 4.0-6.0 volts, go to next step. If voltage is not as specified, reconnect all electrical connections. Go to VEHICLE REFERENCE VOLTAGE testing under SYSTEM TESTS . - 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 is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in TP circuit (Gray/White wire) between TP sensor 3-pin harness connector terminal and PCM 104-pin harness connector terminal No. 89. See WIRING DIAGRAMS article. After repair, go to step 25. - 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 either resistance measurement is more than 10,000 ohms, replace faulty PCM. After repair, go to step 25. If either resistance measurement is 10,000 ohms or less, repair short circuit in harness. See WIRING DIAGRAMS article. After repair, go to step 25. - 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 . - Check Mechanical Operation Of TP Sensor
Turn ignition on, engine off. Acces 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 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. - Check TP Sensor Signal High Versus Engine Load While Driving
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. - Check TP Sensor Signal Low Versus Engine Load While Driving
Drive vehicle exercising throttle near higher gears (preferably overdrive). Observe TP V and LOAD PIDs. 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 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 25. - 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 3-pin harness connector. If connector is okay, replace faulty TP sensor. After repair, go to step 25. - 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 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 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 WIRING DIAGRAMS article. After repair, go to step 25. - Attempt To Re-Create DTC Or Driveability Symptom
If KOER self-test terminates when placing transaxle in Drive or Reverse, go to step next step. Attempt to drive vehicle while still in KOER self-test. Turn igniton 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 25. - 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 (Gray/White wire) between breakout box terminal No. 89 and TP sensor 3-pin harness connector terminal. Record reading. Measure resistance of SIG RTN circuit (Orange wire) between breakout box terminal No. 91 and TP sensor 3-pin harness connector terminal. See Fig 1. Record reading. If either resistance mesurement is less than 5 ohms, replace faulty TP sensor. After repair, go to step 25. If either resistance measurement is 5 ohms or more, repair open circuit. See WIRING DIAGRAMS article. After repair, go to next step. - 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.