Diagnostic Instructions

DTC Descriptors

DTC P0120: Throttle Position (TP) Sensor 1 Circuit

DTC P0121: Throttle Position (TP) Sensor 1 Performance

DTC P0122: Throttle Position (TP) Sensor 1 Circuit Low Voltage

DTC P0123: Throttle Position (TP) Sensor 1 Circuit High Voltage

DTC P0220: Throttle Position (TP) Sensor 2 Circuit

DTC P0222: Throttle Position (TP) Sensor 2 Circuit Low Voltage

DTC P0223: Throttle Position (TP) Sensor 2 Circuit High Voltage

DTC P2135: Throttle Position (TP) Sensor 1-2 Correlation

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
5-Volt Reference	P0606*	--	P0120, P0121, P0122, P0220, P0222, P0450, P0452, P2135	**	--
TP Sensor 1 Signal	P0122	P2135	P0123, P0121	P0123**	P2135
TP Sensor 2 Signal	P0222	P2135	P0121, P0223	P0223**	P2135
Low Reference	--	P2135	P0110, P0113, P0115, P0118, P0120, P0123, P0220, P0223, P0450, P0453	--	--
*Engine cranks but won't start **Internal PCM or TP sensor damage may occur if the circuit is shorted to B+

Typical Scan Tool Data

TP Sensor 1

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The engine coolant temperature is greater than 70°C (158°F) and the ignition is ON with the engine is OFF. Parameter Normal Range: TP Sensor 1 7-21%
5-Volt Reference	*	0%	**
TP Sensor 1 Signal	0%	99%	99%
Low Reference	--	99%	--
*No scan tool communication with control module **Internal PCM or TP sensor damage may occur if the circuit is shorted to B+

TP Sensor 2

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The engine coolant temperature is greater than 70°C (158°F) and the ignition is ON with the engine is OFF. Parameter Normal Range: TP Sensor 2 2.3-2.4 volts
5-Volt Reference	*	0 volts	**
TP Sensor 2 Signal	0.2 volts	5.0 volts	4.65 volts
Low Reference	--	5.0 volts	--
*No scan tool communication with control module **Internal PCM or TP sensor damage may occur if the circuit is shorted to B+

Circuit/System Description

The TP sensor used with the throttle actuator control (TAC) system is actually a Hall Effect switch. The Hall Effect switch is surrounded by a magnetic yoke that induces a flux in the magnetic field when the throttle shaft is rotated. The PCM provides a 5-volt reference voltage to the sensor circuits in the TAC module. An integrated circuit (IC) receives and converts the magnetic pulses into two separate TP signal, each with their own characteristics. The TP sensor  1 output provides the powertrain control module (PCM) with a signal voltage that is proportional to the throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. TP sensor 1 determines the actual throttle valve position. TP sensor 2 has a voltage that is greater than twice that of TP sensor 1 at idle. TP sensor 2 provides a backup value for TP sensor 1.

Conditions for Running the DTC

Conditions for Setting the DTC

P0120

P0121

P0122

The PCM detects that the TP sensor 1 voltage is less than 0.2 volts for greater than 2 seconds.

P0123

The PCM detects that the TP sensor 1 voltage is greater than 4.5 volts for greater than 2 seconds.

P0220

P0222

The PCM detects that the TP sensor 2 voltage is less than 0.5 volts for greater than 2 seconds.

P0223

The PCM detects that the TP sensor 2 voltage is greater than 4.8 volts for greater than 2 seconds.

P2135

Action Taken When the DTC Sets

DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223 and P2135 are Type A DTCs.

Conditions for Clearing the DTC

DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223 and P2135 are Type A DTCs.

Diagnostic Aids

If a shared 5-volt reference circuit is shorted to ground the engine will not start and the PCM will not communicate with the scan tool.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Description and Operation

Throttle Actuator Control (TAC) System Description

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. Ignition ON, observe that the TP sensor 1 scan tool parameter is between 7-19 percent.
2. Ignition ON, observe that the TP sensor 2 scan tool parameter is between 2.3-2.6 volts.
3. Observe both TP sensor parameters while pressing the accelerator pedal from a closed throttle to WOT. Both TP sensor parameters should change.
4. Rapidly depress the accelerator pedal from the rest position to the WOT position and release pedal. Repeat the procedure several times. DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, or P2135 should not set.
5. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, or P2135 should not set.
6. 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

1. Ignition OFF, disconnect the harness connector at the throttle body assembly.
2. Ignition OFF, test for 10 ohms or less between the low reference circuit terminal 3 and ground G104.

⇒	If greater than the specified range, test the low reference circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the PCM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 5 and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the PCM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PCM.

4. Test for 4.8-5.2 volts between the TP sensor signal circuit terminal listed below and ground.

•	TP sensor 1 terminal 6

•	TP sensor 2 terminal 4

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the PCM.

5. If all circuits test normal, test or replace the throttle body assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.