Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptors
DTC P1121: Throttle Position (TP) Sensor Circuit Intermittent High VoltageDTC P1122: Throttle Position (TP) Sensor Circuit Intermittent Low Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
5-Volt Reference | P0122, P1122 | -- | P0122, P1122 | P0123, P1121 | -- |
Throttle Position Sensor Signal | P0122, P1122 | -- | P0122, P1122 | P0123, P1121 | -- |
Low Reference | -- | -- | P0123, P1121 | -- | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: The engine is operating at idle. Parameter Normal Range: TP Position Sensor 0% | |||
5-Volt Reference | 0% | 0% | 99% |
Throttle Position Sensor Signal | 0% | 0% | 99% |
Low Reference | -- | 99% | -- |
Circuit/System Description
The throttle position (TP) sensor is used by the engine control module (ECM) to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with the following 3 circuits:
| • | A 5-volt reference |
| • | A low reference |
| • | A signal |
The ECM provides the TP sensor with 5 volts on the 5-volt reference circuit, and a ground on the low reference circuit. The TP sensor provides a signal voltage feedback that changes relative to throttle plate angle.
Conditions for Running the DTCs
| • | The ignition is ON or the engine is operating. |
| • | The DTCs runs continuously when the above condition is met. |
Conditions for Setting the DTC
P1121
The ECM detects that the TP sensor voltage is greater than 4.9 volts intermittently for greater than 2 seconds during a 60 second time period.
P1122
The ECM detects that the TP sensor voltage is less than 0.14 volt intermittently for greater than 2 seconds during a 60 second time period.
Action Taken When the DTC Sets
DTCs P1121 and P1122 are Type C DTCs.
Conditions for Clearing the MIL/DTC
DTCs P1121 and P1122 are Type C DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Verify that DTCs P0122 or P0123 are not set.
- Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. DTC P1121 or P1122 should not set.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
- Start the engine. Observe the scan tool throttle position (TP) sensor parameter while moving the harness connector of the sensor. The TP sensor parameter should not change abruptly.
- Engine running, observe the scan tool TP sensor parameter while moving the harness connector of the ECM. The TP sensor parameter should not change abruptly.
- Engine running, observe the scan tool TP sensor parameter while moving the wiring harness between the sensor and ECM. The TP sensor parameter should not change abruptly.
| ⇒ | If the TP sensor parameter changes abruptly, repair the harness connector of the TP sensor. |
| ⇒ | If the TP sensor parameter changes abruptly, repair the harness connector of the ECM. |
| ⇒ | If the TP sensor parameter changes abruptly, repair the wiring harness. |
Component Testing
- Ignition OFF, disconnect the harness connector of the TP sensor.
- Measure for 1,160-1,175 ohms between the 5-volt reference and the low reference terminals of the applicable TP sensor.
- Measure the resistance between the signal terminal and the low reference terminal of the TP sensor. Sweep the TP sensor through the entire range. The resistance should vary between 1,530-630 ohms without any spikes or dropouts.
- Apply 5 volts and ground to the applicable terminals of the TP sensor, and measure the voltage between the signal and the low reference terminals. Sweep the TP sensor through the entire range. The voltage should vary between 4.3-0.6 volts without any spikes or dropouts.
| ⇒ | If the resistance is not within the specified range, replace the TP sensor. |
| ⇒ | If the resistance is not within the specified range or is erratic, replace the TP sensor. |
| ⇒ | If the voltage is not within the specified range or is erratic, replace the TP sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Throttle Position Sensor Replacement |
| • | Control Module References for engine control module replacement, setup, and programming |
