Diagnostic Instructions

DTC Descriptor

DTC P0121: Throttle Position Sensor 1 Circuit Range/Performance

DTC P0122: Throttle Position Sensor 1 Circuit Low Voltage

DTC P0123: Throttle Position Sensor 1 Circuit High Voltage

DTC P0221: Throttle Position Sensor 2 Circuit Range/Performance

DTC P0222: Throttle Position Sensor 2 Circuit Low Voltage

DTC P0223: Throttle Position Sensor 2 Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5-Volt Reference	P0122, P0222, P2127	P0121, P0122, P0221, P2101, P2176	P0223, P2101, P2138, P2128, P2119	P0121, P0221
TP Sensor Signal 1	P0122	P0122	P0123	P0121
TP Sensor Signal 2	P0222	P0222	P0223, P0638, P2128, P2138	P0221
Low Reference	--	P0121, P0123, P0221, P0223, P2176	P0123, P0223*	P0121, P0221
* Internal ECM or TP sensor damage may occur if the circuit is shorted to B+

Typical Scan Tool Data

TP Sensor

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The engine is operating in closed loop Parameter Normal Range: TP Position Sensor 5 %/4.2 V
5-Volt Reference	6 %/0.40 V	6 %/0.00 V	14 %/5.00 V
TP Sensor Signal	6 %/0.00 V	6 %/0.00 V	6 %/5.00 V
Low Reference	--	6 %/5.00 V	--

Circuit/System Description

The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5 volt reference circuit, a common low reference circuit and two independent signal circuits. The TP sensors have opposite functionality. TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.

Conditions for Running the DTC

DTC P0121

DTCs P0122, P0123, P0222 and P0223

DTC P0221

Conditions for Setting the DTC

DTC P0121

The TP sensor 1 disagrees greater than 9 percent from TP sensor 2 Or TP sensor 1 disagrees greater than 9 percent from the predicted value. Either condition exists for greater than 4 seconds.

DTC P0122

The ECM detects the TP sensor 1 signal voltage is less than 0.18 volts for greater than 4 seconds.

DTC P0123

The ECM detects the TP sensor 1 signal voltage is greater than 4.6 volts for greater than 4 seconds.

DTC P0221

The TP sensor 1 disagrees greater than 9 percent from TP sensor 2. Or TP sensor 2 disagrees greater than 9 percent from the predicted value. The above conditions are met for greater than 4 seconds.

DTC P0222

The ECM detects the TP sensor 2 signal voltage is less than 0.16 volts for greater than 4 seconds.

DTC P0223

The ECM detects the TP sensor 2 signal voltage is less than 0.16 volts for greater than 4 seconds.

Action Taken When the DTC Sets

DTCs P0121, P0122, P0123, P0221, P0222 and P0223 are type B DTCs.

Conditions for Clearing the DTC

DTCs P0121, P0122, P0123, P0221, P0222 and P0223 are type B DTCs.

Diagnostic Aids

If there is a condition with the TP sensors the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

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, verify that DTC P0697, P0698, or P0699 is not set.

⇒	If a DTC is set, refer to DTC P0641-P0643, P0651-P0653, or P0697-P0699.

2. Ignition ON, clear the DTC with a scan tool.
3. Start the engine, observe the TP Sensor 1 and 2 voltage parameters with a scan tool. TP sensor 1 should be between 0.17-4.6 V and TP sensor 2 should be between 0.15-4.8 V.
4. Observe the scan tool TP sensor 1 and 2 parameters while performing the tests listed below. The TP sensor 1 and 2 parameter should display correlation OK.

•	Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times.

•	Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.

5. Observe the DTC Information with a scan tool. DTCs P0121, P0122, P0123, P0221, P0222 and P0223 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.
2. Ignition OFF, remove the fuse that supplies B+ to terminal 56 X2 of the ECM.

Note: The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.

3. Test for less than 5 Ω between the low reference circuit terminal C and ground.

⇒	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 ECM.

4. Install the fuse that supplies B+ to terminal 56 X2 of the ECM.
5. Ignition ON, test for 4.8-5.2 V between the 5-volt reference circuit terminal E and ground.

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

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

6. Ignition ON, verify that the scan tool TP sensor 1 voltage parameter is less than 0.3 volt.

⇒	If greater than the specified value, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the ECM.

7. Connect a 3A fused jumper wire between the 5 volt reference circuit terminal E and the TP sensor 1 signal circuit terminal D. Verify the scan tool TP sensor 1 voltage parameter is greater than 4.89 V.

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

8. Verify the scan tool TP sensor 2 voltage parameter is greater than 4.97 V.

⇒	If less than the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the ECM.

Note: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage.

9. Connect a 3A fused jumper wire between the TP sensor 2 signal circuit terminal F and the low reference circuit terminal C. Verify the scan tool TP sensor 2 voltage parameter is less than 0.10 V.

⇒	If greater than the specified value, test the signal circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the ECM.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.