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 provides 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 DTC
| • | 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
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine running, observe the DTC Information with a scan tool. Verify that DTCs P0122 or P0123 is not set.
- Observe the DTC Information with a scan tool. DTCs P1121 or P1122 should not set.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
| ⇒ | If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
Engine running, observe the scan tool throttle position (TP) sensor parameter while moving the related wiring harness and harness connectors. The reading should not change abruptly.
| ⇒ | If the reading changes abruptly, repair the wiring harness and harness connectors. |
Component Testing
- Ignition OFF, disconnect the harness connector at the throttle position (TP) sensor.
- Test for 1160-1175 ohms between the 5-volt reference terminal A and the low reference terminal B.
- Slowly sweep the TP sensor through the entire range several times while monitoring the resistance between the signal terminal and the low reference terminal. The resistance should vary between 1530-630 ohms without any spikes or dropouts.
- Slowly sweep the TP sensor through the entire range several times while applying 5 volts and ground to the applicable terminals. Test the voltage between the signal terminal and the low reference terminal. The voltage should vary between 4.3-0.6 volts without any spikes or dropouts.
| ⇒ | If not within the specified range, replace the TP sensor. |
| ⇒ | If not within the specified range or is erratic, replace the TP sensor. |
| ⇒ | If not within the specified range or is erratic, TP sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
