For 1990-2009 cars
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Throttle Position (TP) sensor circuit provides a voltage signal that changes relative to throttle blade angle. The signal voltage will vary from below 1.0 volt at closed throttle to above 4.0 volts at Wide Open Throttle (WOT). The PCM monitors throttle position and compares actual throttle position from the TP sensor to a predicted TP value calculated from engine speed. If the PCM detects an excessively low TP sensor signal voltage, DTC P0122 will be set.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

• | TP sensor signal voltage is less than 0.1 volt.

• | Above conditions are present for longer than 1 second.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.

• | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using the scan tool.

### Diagnostic Aids

Check for the following conditions:

• | Poor connection at PCM and TP Sensor. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Use a corresponding mating terminal to test for proper tension.

• | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the TP Sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. Refer to Intermittents and Poor Connections Diagnosis .

If DTC P0122 cannot be duplicated, the information included in the Fail Records data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing the DTC P1122 Throttle Position (TP) Sensor Circuit Intermittent Low Voltage Diagnostic Table may isolate the cause of the malfunction.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table:

1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Refer to PCM Replacement and Programming Procedures in Powertrain Control Module (PCM) and Sensors..

#### DTC P0122 - TP Sensor Circuit Low Voltage

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the OBD Diagnostic System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | If P1635 is also set, perform DTC P1635 5 Volt Reference Circuit first.

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the TP voltage parameter in the PCM data list.

Does the scan tool indicate that the TP voltage parameter is less than the specified value?

0.16V

Go to Step 4

Go to Step 3

3 |

1. Turn ON the ignition switch.
2. Review and record scan tool Fail Records data.
3. Operate the vehicle within Fail Records conditions as noted.
4. Using a scan tool, monitor Specific DTC info for DTC P0122.

Does the scan tool indicate DTC P0122 failed?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn OFF the ignition.
2. Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the TP sensor and the signal circuit of the TP sensor.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the TP voltage parameter.

Does the scan tool indicate that the TP voltage parameter is equal to the specified value?

5V

Go to Step 9

Go to Step 5

5 |

1. Disconnect the fused jumper wire.
2. Using a J 39200 , measure the voltage between the 5 volt reference circuit of the TP sensor and the ground circuit of the TP sensor.

Does the voltage measure equal to the specified value?

5V

Go to Step 7

Go to Step 6

6 | Test the 5 volt reference circuit of the TP sensor for high resistance or an open and all 5 volt reference A circuits and connected components for a short to ground. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8
7 | Test the signal circuit of the TP sensor for a short to ground, a high resistance, or an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8
8 | Inspect for poor connections at the harness connector of the PCM. Refer to Intermittents and Poor Connections Diagnosis . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11
9 | Inspect for poor connections at the harness connector of the TP sensor. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10
10 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement Did you complete the replacement? | -- | Go to Step 12 | --
11 | Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | Go to Step 12 | --
12 |

1. Review and record scan tool Fail Records data.
2. Clear DTCs
3. Operate the vehicle within Fail Records conditions as noted.
4. Using a scan tool, monitor Specific DTC info for DTC P0122.

Does the scan tool indicate DTC P0122 failed?

--

Go to Step 4

System OK