For 1990-2009 cars

### 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 Voltage
DTC 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

#### TP Position Sensor

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 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 more 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 more 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

Engine Controls Schematics

#### Connector End View Reference

• | Engine Controls Component Views

• | Engine Control Module Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Verify that DTCs P0122 or P0123 are not set.

⇒ | If any of the DTCs are set, refer to DTC P0122 or P0123 .

2. 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.
3. 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.

### Circuit/System Testing

1. Start the engine. Observe the throttle position (TP) sensor parameter while moving the harness connector of the sensor. The TP sensor parameter should not change abruptly.

⇒ | If the TP sensor parameter changes abruptly, repair the harness connector of the TP sensor.

2. Engine running, observe the TP sensor parameter while moving the harness connector of the ECM. The TP sensor parameter should not change abruptly.

⇒ | If the TP sensor parameter changes abruptly, repair the harness connector of the ECM.

3. Engine running, observe the 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 wiring harness.

### Component Testing

1. Ignition OFF, disconnect the harness connector of the TP sensor.
2. Measure for 1160-1175 ohms between the 5-volt reference and the low reference terminals of the applicable TP sensor.

⇒ | If the resistance is not within the specified range, replace the TP sensor.

3. 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 1530 and 630 ohms without any spikes or dropouts.

⇒ | If the resistance is not within the specified range or is erratic, replace the TP sensor.

4. 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 voltage is not within the specified range or is erratic, TP sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Throttle Position Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming