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 P0122: Throttle Position (TP) Sensor Circuit Low VoltageDTC P0123: Throttle Position (TP) Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
5-Volt Reference | P0122 | P0122 | P0122 | -- |
TP Sensor Signal | -- | P0122 | P0123 | -- |
Low Reference | -- | P0123 | -- | -- |
Typical Scan Tool Data
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 Volts | |||
5-Volt Reference | 6 %/0.40 Volts | 6 %/0.00 Volts | 14 %/5.00 Volts |
TP Sensor Signal | 6 %/0.00 Volts | 6 %/0.00 Volts | 6 %/5.00 Volts |
Low Reference | -- | 6 %/5.00 Volts | -- |
Circuit/System Description
The throttle body assembly contains a throttle position (TP) sensor. The TP sensor is mounted externally on the throttle body assembly. The TP sensor is a potentiometer which provides a signal voltage that changes relative to the throttle blade angle. The engine control module (ECM) supplies the TP sensor with a 5-volt reference circuit, a low reference circuit, and a signal circuit. The TP sensor signal voltage decreases from less than 1 volt at idle to more than 4 volts at wide open throttle (WOT).
Conditions for Running the DTC
| • | The ignition is ON or the engine is operating. |
| • | The DTCs runs continuously when the above condition is met. |
Conditions for Setting the DTC
Important: The scan tool displays a voltage near 0.0 volts. Do not use the scan tool voltage parameter to determine if there is a TP sensor condition.
P0122
The ECM detects that the TP sensor voltage is less than 0.14 volt for more than 5 seconds.
P0123
The ECM detects that the TP sensor voltage is more than 4.9 volts for more than 5 seconds.
Action Taken When the DTC Sets
DTC P0122 and P0123 are Type A DTCs.
Conditions for Clearing the DTC
DTC P0122 and P0123 are Type A DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
Start the engine, observe the TP Sensor voltage parameter with a scan tool. The parameters should be between 0.4-4.5 volts.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector of the TP sensor.
- Ignition ON, verify that the TP sensor voltage parameter is less than 0.3 volt.
- Ignition ON, connect a test lamp between the 5-volt reference circuit of the TP sensor and a good ground.
- Test for 4.8-5.2 volts between the 5-volt reference circuit of the TP sensor and a good ground.
- Ignition ON, test for less than 0.2 volt between the low reference circuit of the TP sensor and a good ground.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the TP sensor and a good ground.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the TP sensor to verify that the TP sensor voltage parameter is greater than 4.8 volts.
- If all circuits/connections test normal, test or replace the TP sensor.
| ⇒ | If greater than 0.3 volt, test the signal circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the engine control module (ECM). |
Important: The test lamp is used to load the circuit and may not illuminate.
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 4.8 volts, test the 5-volt reference circuit of the TP sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If greater than 5.2 volts, test the 5-volt reference circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If greater than 0.2 volt, test the low reference circuit of the TP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If greater than 5 ohms, test the low reference circuit of the TP sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If less than 4.8 volts, test the appropriate signal circuit of the TP sensor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the engine control module (ECM). |
Component Testing
- Turn OFF the ignition.
- Measure for 5150-5350 ohms between the 5-volt reference and the low reference terminals of the TP sensor .
- Measure the resistance between the signal terminal and the low reference terminal of the TP sensor. Slowly sweep the TP sensor through the entire range several times. The resistance should vary between 2500 and 6800 ohms without any spikes or dropouts.
- 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. Slowly sweep the TP sensor through the entire range several times. The voltage should vary between 0.6-4.7 volts without any spikes or dropouts.
| ⇒ | If the resistance is not within the specified range, replace the TP sensor. |
| ⇒ | If the resistance is not within the specified range or is erratic, replace the TP sensor. |
| ⇒ | 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.
| • | Control Module References for engine control module replacement, setup, and programming |
