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 provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0121: Throttle Position (TP) Sensor 1 PerformanceDTC P0122: Throttle Position (TP) Sensor 1 Circuit Low Voltage
DTC P0123: Throttle Position (TP) Sensor 1 Circuit High Voltage
DTC P0221: Throttle Position (TP) Sensor 2 Performance
DTC P0222: Throttle Position (TP) Sensor 2 Circuit Low Voltage
DTC P0223: Throttle Position (TP) Sensor 2 Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
5-Volt Reference | -- | -- | P0122, P0222 | -- | -- |
Throttle Position Sensor 1 Signal | P0122 | P0121 | P0123 | P0123 | P0121 |
Throttle Position Sensor 2 Signal | P0222 | P0221 | P0222 | P0223 | P0221 |
Low Reference | -- | -- | P0123, P0223 | -- | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: The engine is operating at idle. Parameter Normal Range: TP Sensor 1 11-14%, 0.65-0.85 Volts | |||
5-Volt Reference | 0%, 0 Volts | 0%, 0 Volts | 100%, 5 Volts |
TP Sensor 1 Signal | 0%, 0 Volts | 0%, 0 Volts | 100%, 5 Volts |
Low Reference | -- | 100%, 5 Volts | -- |
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: The engine is operating at idle. Parameter Normal Range: TP Sensor 2 4.1-4.3 Volts | |||
5-Volt Reference | 0 Volts | 0 Volts | 5 Volts |
TP Sensor 2 Signal | 0 Volts | 5 Volts | 5 Volts |
Low Reference | -- | 5 Volts | -- |
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 2 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
P0121 or P0221
| • | DTCs P0101, P0102, P0103, P0107, or P0108 are not set. |
| • | The ignition is ON or the engine is running. |
| • | The actual TP value is less than 90 percent. |
| • | The DTCs run continuously once the above conditions are met. |
P0122, P0123, P0222, or P0223
| • | The ignition is ON or the engine is running. |
| • | The DTCs run continuously once the above condition is met. |
Conditions for Setting the DTC
P0121 or P0221
The ECM detects the difference between TP sensor 1 and TP sensor 2 is greater than 6 percent for greater than 30 seconds.
P0122
The ECM detects that the TP sensor 1 voltage is less than 0.4 volt for less than 1 second.
P0123
The ECM detects that the TP sensor 1 voltage is greater than 4.6 volts for less than 1 second.
P0222
The ECM detects that the TP sensor 2 voltage is less than 0.1 volt for less than 1 seconds.
P0223
The ECM detects that the TP sensor 2 voltage is greater than 4.9 volts for less than 1 seconds.
Action Taken When the DTC Sets
DTCs P0121, P0122, P0123, P0221, P0222, and P0223 are Type A DTCs.
Conditions for Clearing the DTC
DTCs P0121, P0122, P0123, P0221, P0222, and P0223 are Type A DTCs.
Diagnostic Aids
If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.
Reference Information
Schematic Reference
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
- Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0642 or P0643 is not set.
- Observe the scan tool TP Sensor parameters. Verify TP sensor 1 is 0.6-0.8 volts and TP sensor 2 is 4.1-4.3 volts.
- Engine running, rapidly depress the accelerator pedal from the rest position to the WOT position and release pedal. Repeat the procedure several times. DTCs P0121, P0122, P0123, P0221, P0222, or P0223 should not set.
- Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTCs P0121, P0122, P0123, P0221, P0222, or P0223 should not set.
- 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.
| ⇒ | If any of the DTCs are set, refer to DTC P0642 or P0643. |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the throttle body assembly.
- Ignition OFF for at least 20 seconds, test for less than 10 ohms of resistance between the low reference circuit terminal 3 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 1 and ground.
- Verify the scan tool TP sensor voltage parameter is less than 0.3 volt.
- Install a 3A fused jumper wire between the appropriate signal circuit and the 5-volt reference circuit terminal 1. Verify the scan tool TP sensor voltage parameter is greater than 4.8 volts.
- If all circuits test normal, replace the throttle body assembly.
| ⇒ | 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. |
Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.
| ⇒ | If less than the specified range, test the 5-volt reference 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 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the appropriate signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| • | TP sensor 1 signal terminal 4 |
| • | TP sensor 2 signal terminal 2 |
| ⇒ | If less than the specified range, test the appropriate signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If both TP sensor voltage parameters display greater than the specified range, test the signal circuits for a shorted together condition. If the circuit tests normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
