For 1990-2009 cars
Engine Controls Components
Engine Data Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Powertrain Control Module (PCM) supplies a 5.0 volt reference signal and a ground to the sensor. The TP sensor sends a voltage signal back to the PCM relative to the throttle plate opening. The voltage will vary from approximately 0.35 volt at closed throttle, to over 4.65 volts at wide open throttle (WOT).

### Conditiions for Setting the DTC

• | Engine is running.

• | The TP sensor voltage is greater than 3.9 V for 13.75 seconds.

• | MAP is less than 60 kPa.

• | Engine speed is less than 1500 RPM.

• | DTCs P0107 or P0108 not set.

| Or

• | TP sensor voltage is greater than 4.8 V.

• | DTCs P0107 or P0108 not set.

### Action Taken When the DTC Sets

• | The Malfunction Indicator Lamp (MIL) will illuminate.

• | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.

• | A history DTC stores.

• | The coolant fan turns ON.

• | The TP angle will default to 0 percent when the vehicle speed is less than 3 km/h (2 mph) and 10 percent when the vehicle speed is greater than 3 km/h (2 mph) (The scan tool will display the defaulted value).

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.

• | A history DTC will clear after 40 consecutive warm-up cycles without a fault.

• | The MIL/DTCs can be cleared by using the scan tool.

### Diagnostic Aids

If a DTC P0123 cannot be duplicated, the information included in the Freeze Frame data can be useful. Use the scan tool DTC information data to determine the status of the DTC. If the DTC occurs intermittently, use the DTC P0121 Diagnostic table in order to help isolate the problem.

• | With the ignition ON and the throttle at closed position, the voltage should read between 0.20V and 0.90V and increase steadily to over 4.5V at wide open throttle.

• | DTCs P0123 and P0113 stored at the same time could be the result of an open sensor ground circuit.

### Test Description

The numbers below refers to the step numbers on the Diagnostic Table.

1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.

2. With the throttle closed, the TP sensor voltage should read less than 0.80 volts. If the TP sensor voltage does not read less than 0.80 volts, check for a binding or a sticking throttle cable.

3. The PCM and the wiring are OK if the TP sensor voltage is less than 0.3 volts with the TP sensor electrical connector disconnected.

4. Probing the ground circuit with a test light checks the circuit for high resistance which will cause a DTC P0123 to set.

5. Important: The Powertrain Control Module (PCM) uses a single internal 5.0 volt power supply to supply power to all the engine control components. If one component shorts its 5.0 volt reference circuit to ground or battery voltage, the other 5.0 volt reference circuits will also have a low or high voltage.

   A shorted 5.0 volt reference circuit will also set additional DTCs.

6. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Techline information for PCM programming and the Crankshaft Position System Variation Learn .

#### DTC P0123-Throttle Position (TP) Sensor Circuit-High Voltage

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition switch leaving the engine OFF.
2. Verify that the throttle is closed.
3. Install a scan tool.

Is the TP sensor voltage greater than the specified value?

0.8 V

Go to Step 4

Go to Step 3

3 |

1. Review the Freeze Frame data and record the parameters.
2. Start the engine.
3. Operate the vehicle within the Freeze Frame conditions and Conditions For Setting the DTC as specified.

Is the TP sensor voltage greater than the specified value?

3.9 V

Go to Step 4

Go to Step 12

4 |

1. Turn OFF the ignition switch.
2. Disconnect the TP sensor electrical connector.
3. Turn ON the ignition switch leaving the engine OFF.

Is the TP sensor voltage less than the specified value?

0.3 V

Go to Step 5

Go to Step 6

5 |

1. Connect a test light to B+.
2. Probe the TP sensor ground circuit terminal at the TP sensor harness electrical connector.

Does the test light illuminate?

--

Go to Step 7

Go to Step 9

6 |

1. Turn OFF the ignition switch.
2. Check the TP sensor signal circuit for a short to voltage.
3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 11

7 | Important: The Powertrain Control Module (PCM) uses a single internal 5.0 volt power supply to supply power to all the engine control components. If one component shorts its 5.0 volt reference circuit to ground or battery voltage, the other 5.0 volt reference circuits will also have a low or high voltage.

1. Check the TP sensor 5.0 V reference circuit for a short to B+.
2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 8

8 |

1. Check the TP sensor ground circuit electrical connector for a poor electrical terminal connection.
2. Replace the terminals as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 10

9 |

1. Turn OFF the ignition switch.
2. Check for an open in the TP sensor ground circuit.
3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 12

Go to Step 11

10 | Replace the TP sensor. Refer to the Throttle Position Sensor Replacement . Is the action complete? | -- | Go to Step 12 | --
11 |

1. Check for a poor electrical connection at the PCM electrical connector.
2. If the electrical connection is OK, replace the PCM. Refer to the Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 12

--

12 |

1. Clear the DTCs with the scan tool.
2. Start the engine.
3. Idle the engine at the normal operating temperature.
4. Operate the vehicle within the conditions for setting the DTC as specified in the supporting text.

Does the scan tool indicate that the diagnostic ran and passed?

--

Go to Step 13

Go to Step 2

13 | Check to see if any additional DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK