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DTC P0121 [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513)

BME010200100212

DTC P0121 | Throttle position stuck close (lower than expected)/open (higher than expected)
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DETECTION CONDITION | • If PCM detects that throttle valve opening angle is below 12.5% for 5 s after following conditions are met, PCM determines that TP is stuck close: MONITORING CONDITION

  - Engine coolant temperature above 70 °C {158 °F}
  - MAF sensor signal above 88.3 g/s {11.7 lb/min.}

• If PCM detects that throttle valve opening angle is above 50% for 5 s after following conditions are met, PCM determines that TP is stuck open:
MONITORING CONDITION

  - Engine speed above 500 rpm
  - MAF sensor signal below 8.93 g/s {1.18 lb/min.}

Diagnostic support note
• This is a continuous monitor (CCM).
• MIL illuminates if PCM detects the above malfunction conditions in two consecutive drive cycles.
• PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.
POSSIBLE CAUSE | • TP sensor malfunction • Electrical corrosion in TP signal circuit • Voltage drops in constant voltage (Vref) supply circuit • Voltage drops in ground circuit • MAF sensor malfunction
• PCM malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record FREEZE FRAME DATA on repair order, then go to the next step.
2 | VERIFY RELATED PENDING CODE OR STORED DTC • Turn the ignition switch to the ON position (Engine off). • Retrieve pending or stored DTC using WDS or equivalent. • Is DTC P0101 also retrieved? | Yes | Go to DTC P0101 troubleshooting procedure.
No | Go to the next step.
3 | VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Check for related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to available Service Information. • If vehicle is not repaired, go to the next step.
No | Go to the next step.
4 | VERIFY CURRENT INPUT SIGNAL STATUS - IS CONCERN INTERMITTENT OR CONSTANT • Start the engine. • Access ECT, TP and MAF PIDs using WDS or equivalent. • Warm up the engine until ECT PID is above 70 °C {158 °F} • Drive the vehicle.
• Read TP PID while MAF PID is above 88.3 g/s {11.7 lb/min.}.
• Is TP PID reading above 12.5%?
Yes
Go to Step 7.
No | Go to the next step.
5 | VERIFY TP PID • Start the engine. • Access TP, MAF and RPM PIDs using WDS or equivalent. • Read TP PID while MAF PID is below 8.93 g/s {0.7 lb/min.} and RPM PID is above 500 rpm. • Is TP PID reading above 50%? | Yes | Go to Step 12.
No | Go to the next step.
6 | VERIFY CURRENT INPUT SIGNAL STATUS - IS CONCERN INTERMITTENT OR CONSTANT • Drive the vehicle and read MAF PID. • Does MAF PID change in compliance with driving condition? | Yes | Intermittent concern exists. Go to INTERMITTENT CONCERNS troubleshooting procedure.
No | Check Mass airflow sensor and related circuits and terminals. (See MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR INSPECTION [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513).)
Repair or replace as necessary, then go to Step 16.
7 | CHECK TP SENSOR TERMINALS FOR ELECTRICAL CORROSION • Turn the ignition switch off. • Disconnect TP sensor connector • Inspect for electrical corrosion on male and female TP sensor terminals. • Is any electrical corrosion found? | Yes | Repair or replace suspected terminal or TP sensor, then go to Step 11.
No | Go to the next step.
8 | INSPECT TP SENSOR • Does the TP sensor resistance smoothly change while gradually opening throttle valve? | Yes | Go to the next step.
No | Replace the TP sensor, then go to Step 11.
9 | INSPECT PCM TERMINALS FOR ELECTRICAL CORROSION • Disconnect PCM connector. • Inspect for electrical corrosion on PCM male and female terminals. • Is any electrical corrosion found? | Yes | Repair the terminal, then go to Step 11.
No | Go to the next step.
10 | CHECK CONSTANT VOLTAGE SUPPLY AND TP SIGNAL CIRCUITS FOR VOLTAGE DROP • Connect the PCM connector. • Turn the ignition switch to the ON position (Engine off). • Measure the voltage between following terminals:

  - TP sensor connector terminal C (wiring harness-side) and PCM terminal 90
  - TP sensor connector terminal B (wiring harness-side) and PCM terminal 89

• Is the voltage approx. 0 V?
Yes
Go to the next step.
No | Inspect for rust or corrosion on PCM terminals 89 and 90 (wiring harness-side). • Repair or replace the terminal. Go to the next step.
11 | VERIFY TROUBLESHOOTING OF DTC P0121 COMPLETED • Make sure to reconnect all disconnected connectors. • Start the engine. • Clear the DTC from the PCM memory using the WDS or equivalent. • Access ECT, TP and MAF PIDs using WDS or equivalent.
• Warm up the engine until ECT PID is reading above 70 °C {158°F}.
• Drive the vehicle and read TP and MAF PIDs.
• Verify PIDs reading are within specifications
MAF PID: above 88.3 g/s {11.7 lb/min.}
TP PID: above 12.5% above 5 s
• Is the PENDING CODE of same DTC present?
Yes
Replace the PCM, then go to Step 17.
No | Go to Step 17.
12 | CHECK TP SENSOR TERMINALS FOR ELECTRICAL CORROSION • Turn the ignition switch off. • Disconnect the TP sensor connector. • Inspect for electrical corrosion on male and female TP sensor terminals. • Is any electrical corrosion found? | Yes | Repair or replace the terminal or TP sensor, then go to Step 16.
No | Go to the next step.
13 | INSPECT GROUND CIRCUIT FOR VOLTAGE DROP • Inspect resistance between TP sensor terminal A (wiring harness-side) and body ground. • Is resistance approx. 0 ohm ? | Yes | Go to the next step.
No | Repair or replace for rust or corrosion on PCM terminal 91 (wiring harness-side) • Repair or replace the terminal. Go to Step 16.
14 | VERIFY TP SENSOR • Does resistance smoothly change while gradually opening throttle valve? | Yes | Go to the next step.
No | Replace the TP sensor, then go to Step 16.
15 | CHECK PCM TERMINALS FOR ELECTRICAL CORROSION • Disconnect the PCM connector. • Inspect for electrical corrosion on PCM and PCM connector male and female terminals. • Is any electrical corrosion found? | Yes | Repair the terminal, then go to the next step.
No | Go to the next step.
16 | VERIFY TROUBLESHOOTING OF DTC P0121 COMPLETED • Make sure to reconnect all disconnected connectors. • Start the engine. • Clear the DTC from the PCM memory using the WDS or equivalent. • Access RPM, TP and MAF PIDs using WDS or equivalent.
• Verify TP PID is reading below 50% while MAF PID is below 8.25 g/s {1.09 lb/min.} and RPM PID is above 500 rpm.
• Is the PENDING CODE of same DTC present?
Yes
Replace the PCM, then go to the next step.
No | Go to the next step.
17 | VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [AJ].) • Is there any DTC present? | Yes | Go to the applicable DTC inspection. (See DTC TABLE [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513).)
No | Troubleshooting completed.