For 1990-2009 cars

### Circuit Description

The throttle position (TP) sensor is used by the powertrain control module (PCM) to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with 3 circuits:

• | A 5-volt reference circuit

• | A low reference circuit

• | A signal circuit

The PCM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from the closed throttle position to the wide open throttle (WOT) position provides the PCM with a signal voltage from less than 1.0 volt to greater than 4.0 volts through the TP sensor signal circuit. If the PCM detects an excessively low signal voltage, this diagnostic trouble code (DTC) will set.

### Conditions for Running the DTC

The ignition is ON.

### Conditions for Setting the DTC

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

• | The above condition is present for longer than 1 second.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Test Description

The number below refers to the step number on the diagnostic table.

1. Malfunctioning components that share the TP sensor 5-volt reference circuit could cause a low voltage condition on this circuit.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

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

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

0.1 V

Go to Step 4

Go to Step 3

3 |

1. Observe the Freeze Frame/Failure Records data for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Operate the vehicle within the Conditions for Running the DTC, or as close to the data in the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 4

Go to DTC P1122 Throttle Position (TP) Sensor Circuit Intermittent Low Voltage

4 |

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

Does the scan tool indicate TP sensor voltage is at the specified value?

5 V

Go to Step 11

Go to Step 5

5 |

1. Disconnect the fused jumper wire.
2. With a DMM, test for voltage between the 5-volt reference circuit of the TP sensor, and the low reference circuit of the TP sensor.

Does the DMM indicate voltage near the specified value?

5 V

Go to Step 9

Go to Step 6

6 | With a DMM, test the TP sensor 5-volt reference circuit for an open or for high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 7
7 | Test all 5-volt reference circuits for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 8
8 |

1. With a DMM connected between the TP sensor 5-volt reference circuit and the TP sensor low reference circuit, observe voltage while disconnecting all sensors, one at a time, that use a 5-volt reference signal. A change in voltage indicates the faulty component.
2. Replace that component as necessary. Refer to the appropriate replacement procedure.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

9 | With a DMM, test the TP sensor signal circuit for an open, for high resistance, or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10
10 | Inspect for poor connections at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13
11 | Inspect for poor connections at the TP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12
12 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | --
13 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 14 | --
14 |

1. Use a scan tool in order to clear the DTCs.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 15

Go to Step 2

15 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List/Type | System OK