Diagnostic Instructions

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:

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

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

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Circuit/System Verification

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

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

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 scan tool 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 scan tool 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 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 wiring harness.

Component Testing

1. Ignition OFF, disconnect the harness connector of the TP sensor.
2. Measure for 1,160-1,175 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 1,530-630 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, replace the TP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.