Circuit Description
The throttle position (TP) sensor is used by the powertrain control module (PCM) in order to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with the following circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The PCM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from the closed throttle position to the wide-open throttle (WOT) position provides the PCM with a signal voltage from less than 1 volt to greater than 4 volts through the TP sensor signal circuit. When the Conditions for Running the DTC are met, the PCM will use the manifold absolute pressure (MAP) sensor in order to determine if the predicted operating range of the TP sensor is correct. A skewed MAP sensor may cause this DTC to set and should be tested for proper operation if the TP sensor is determined to be operating properly and this DTC continues to set.
Conditions for Running the DTC
| • | No other active TP sensor or MAP sensor DTCs are set. |
| • | The engine is running for more than 2 minutes. |
| • | The engine coolant temperature (ECT) is greater than 75°C (167°F). |
| • | The MAP reading is less than 50 kPa for a TP sensor skewed high test. |
| • | The MAP reading is greater than 70 kPa for a TP sensor skewed low test. |
| • | The MAP is steady for 0.5 seconds or more. |
Conditions for Setting the DTC
| • | The TP sensor reading is greater than a predicted value when the MAP is below 50 kPa. |
| • | The TP sensor reading is less than a predicted value when the MAP is above 70 kPa. |
| • | The above conditions are present for 5 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | A skewed MAP signal--A skewed MAP signal may cause the PCM to incorrectly determine the TP sensor is out of range. Inspect for an unusually low or high MAP reading. |
| • | If the DTC is determined to be intermittent or if the TP sensor system is still suspect, refer to DTC P1121 and/or Symptoms - Engine Controls . |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||
2 |
Important: : If any other DTCs are set, diagnose those DTCs first.
Does the TP angle increase steadily and evenly from the closed throttle value to above the WOT value? | 0 % 98 % | Go to Step 3 | Go to Step 4 | ||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||
4 |
Does the scan tool indicate TP sensor voltage at the specified value? | 0 V | Go to Step 5 | Go to Step 6 | ||||
5 |
Does the scan tool indicate TP sensor voltage at the specified value? | 5 V | Go to Step 9 | Go to Step 7 | ||||
6 | With a DMM, test the TP sensor signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | ||||
7 | With a DMM, test the TP sensor 5-volt reference circuit for an open or high resistance. Refer to Wiring Repairs and Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 8 | ||||
8 | Test the TP sensor signal circuit for an open or high resistance. Refer to Wiring Repairs and Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 | ||||
9 | Test the TP sensor low reference circuit for an open or high resistance. Refer to Wiring Repairs and Circuit Testing in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 10 | ||||
10 | Test the TP sensor 5-volt reference circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 | ||||
11 | Inspect for a poor connection at the TP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | ||||
12 | Inspect for a poor connection at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 | ||||
13 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||
15 |
Does the DTC run and pass? | -- | Go to Step 16 | Go to Step 2 | ||||
16 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||
