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 3 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 1.0 volt to more than 4.0 volts through the TP sensor signal circuit. If the PCM detects an excessively high signal voltage, this diagnostic trouble code (DTC) will set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The TP sensor signal voltage is more than 4.9 volts. |
| • | The above conditions are present for more than 1 second. |
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. |
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 |
Is the voltage more than the specified value? | 4.9 V | Go to Step 4 | Go to Step 3 |
3 |
Does the diagnostic test fail this ignition? | -- | Go to Step 4 | Go to DTC P1121 |
4 |
Does the voltage equal the specified value? | 0 V | Go to Step 5 | Go to Step 7 |
5 | Use a DMM in order to test for voltage on the 5-volt reference circuit of the sensor. Does the voltage equal the specified value? | 5 V | Go to Step 6 | Go to Step 8 |
6 | Test the low reference circuit of the TP sensor for a high resistance and for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
7 | Test the signal circuit of the TP sensor for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
8 | Test all of the 5-volt reference circuits for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
9 | Inspect for poor connections at the TP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
10 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
11 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 |
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
