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 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

Engine Controls Schematics

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

1. Engine running, observe the DTC information with a scan tool. Verify that DTC P0122 or P0123 is not set.

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

2. Observe the DTC information with a scan tool. DTCs P11221 or P1122 should not set.
3. 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.

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.

Component Testing

1. Ignition OFF, disconnect the harness connector at the TP sensor.
2. Test for 1,160-1,175 ohms between the 5-volt reference terminal A and the low reference terminal B.

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

3. Sweep the TP sensor through the entire range while monitoring the resistance between the signal terminal C and the low reference terminal B. The resistance should vary between 1,530-630 ohms without any spikes or dropouts.

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

4. Sweep the TP sensor through the entire range while applying 5 volts and ground to the applicable terminals. Test the voltage between the signal terminal C and the low reference terminal B. The voltage should vary between 4.3-0.6 volts without any spikes or dropouts.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.