For 1990-2009 cars
Handling ESD Sensitive Parts Notice
Engine Controls Components
Engine Controls (Throttle Position (TP) Sensor)
OBD II Symbol Description Notice

### Circuit Description

The throttle position (TP) sensor is part of the throttle body assembly. The TP sensor is actually 2 individual sensors within one housing. The TP sensor 1 is the main input to the engine control module (ECM) for actual throttle positioning. Each of the TP sensors share a common 5 volt reference circuit and a reference ground circuit. The 5 volt reference circuit is also shared with accelerator pedal position (APP) sensor 2. The 5 volt reference voltage is supplied on two separate ECM terminals, but the terminals are connected internally to the same voltage supply. The TP sensor 1 signal circuit is pulled up near 5 volts in the ECM and the signal circuit for TP sensor 2 is referenced to ground. This causes each TP sensor to have opposite functionality. The TP sensor 1 signal voltage increases as the throttle opens, from below 1.0 volt at 0 percent throttle to above 4.0 volts at 100 percent throttle. The TP sensor 2 signal voltage decreases from around 4.0 volts at 0 percent throttle to below 1.0 volt at 100 percent throttle.

### Conditions for Running the DTC

The battery voltage is more than 7.0 volts.

The engine is running.

### Conditions for Setting the DTC

• | The TP sensor 2 voltage is less than 0.156 volt or more than 4.8 volts.

• | The difference between TP sensor 1 and TP sensor 2 is more than 13 percent.

• | One of the above conditions is met for 140 ms (0.140 seconds).

### Action Taken When the DTC Sets

• | The ECM illuminates the malfunction indicator lamp (MIL) on the first drive trip that the diagnostic runs and fails.

• | The ECM attempts to record the operating conditions in the Freeze Frame.

### Conditions for Clearing the MIL/DTC

• | The ECM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes.

• | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.

• | The scan tool clears the MIL/DTC.

### Diagnostic Aids

The ECM compares the signal of each of the throttle position sensors to each other throughout the entire range of the throttle plates. The ECM also compares the signal of the throttle position sensors to other sensors when the engine is running to determine if the sensor readings are correct. Clear the DTCs and actuate the throttle through the entire range with the ignition ON and the engine OFF and also with the engine running. If the DTC resets, check all of the circuits to the throttle position sensors for high resistance. Resistance as low a 2 ohms in the TP sensor circuits can affect the operation of the sensors. Test the reference ground circuit of the TP sensors for a short to ground. The reference ground circuit is provided by the ECM and an external short to ground will affect the operation of the sensors. The reference ground is shared with other components so any faults on this circuit can affect the operation of the entire engine controls system. Refer to Circuit Testing in Wiring Systems.

With the ignition ON and the engine OFF, view the TP sensor 1 and the TP sensor 2 with a scan tool. Slowly depress the accelerator pedal, the voltage on TP sensor 1 should increase steadily from 0.7 volt to about 4.2 volts. TP sensor 2 should move opposite from above 4.2 volts to about 0.6 volt. If one sensor value changes and the other does not, inspect the sensor circuits for high resistance or shorts. If the circuits are OK, replace the throttle body assembly.

Clear the DTCs and turn ON the ignition with the engine OFF for 30 seconds. If a DTC P1526 sets, this indicates there is still a problem with in one of the TP circuits or with the sensors.

Use the J 35616 connector test adapter kit for any test that requires probing the ECM harness connector or a component harness connector.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for Intermittent conditions.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The ECM performs a comparison of the signals from both throttle position sensors during the entire range of operation. If the DTC does not set with the key on and the accelerator pedal released, actuating the throttle may cause the DTC to set.

2. Use the Engine Speed Control function located under TAC System in the scan tool menu to increase the engine RPM. This DTC requires engine RPM and throttle position to be off idle in order for the diagnostic to run.

3. This step tests the integrity of the TP sensor 2 signal circuit. The TP sensor 2 data parameter should read near 5 volts when connected to the 5 volt reference circuit.

4. This step is to test the integrity of the reference ground circuit through the ECM. A small amount of current will appear on this circuit when the ECM is operational. The measured resistance of this circuit will increase when the ECM is operational. This is considered normal.

5. The 5 volt reference for the TP sensors and APP sensor 2 are connected inside the ECM. This step is to determine if the APP sensor is affecting the 5 volt reference circuit of the TP sensors.

6. The 5 volt reference for the TP sensors and APP sensor 2 are connected inside the ECM. A short to voltage on the 5 volt reference circuit of APP sensor 2 will affect the 5 volt reference circuit of the TP sensors.

7. The 5 volt reference for the TP sensors and APP sensor 2 are connected inside the ECM. A short to ground on the 5 volt reference circuit of APP sensor 2 will affect the 5 volt reference circuit of the TP sensors.

8. Additional resistance in any one of the throttle position sensor circuits can effect the operation of the sensors.

9. Additional resistance on the reference ground circuit can affect the operation of the sensors.

Step | Action | Values | 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 | Is DTC P1120 also set? | -- | Go to DTC P1120 Throttle Position (TP) Sensor 1 Circuit | Go to Step 3
3 |

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

Does the scan tool indicate that the TP sensor 2 parameter is within the specified range?

4.6 V to 0.2 V

Go to Step 4

Go to Step 6

4 |

1. Turn OFF the ignition for 30 seconds.
2. Turn ON the ignition, with the engine OFF.
3. Use the scan tool in order to clear the DTC information.
4. Set the vehicle parking brake.
5. Start the engine and allow it to idle.
6. Quickly depress the accelerator pedal to wide open throttle and then return it to the closed position. Repeat this action several times.

Does this DTC set?

--

Go to Step 20

Go to Step 5

5 |

1. Use the scan tool special functions in order to set the engine speed to the specified value.
2. Continue to monitor the DTC information with the scan tool.
3. Move the TP harness and the related connectors while monitoring the DTC information.

Does the harness movement cause this DTC to reset?

1400 RPM

Go to Step 22

Go to Diagnostic Aids

6 |

1. Turn OFF the ignition.
2. Disconnect the TP sensor.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the TP sensor 2 parameter in the engine data list.

Does the scan tool indicate that the TP sensor 2 parameter is less than the specified value?

0.2 volts

Go to Step 7

Go to Step 16

7 | Measure the voltage between the 5 volt reference circuit of the TP sensor and battery ground using the DMM. Does the voltage measure within the specified value? | 4.8-5.2 V | Go to Step 8 | Go to Step 12
8 |

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

Does the scan tool indicate that the TP sensor 2 parameter is within the specified range?

4.8-5.2 V

Go to Step 9

Go to Step 17

9 |

Important: Make sure the ECM has shut down prior to measuring the resistance on the reference ground circuit. This can be verified by the loss of communication with the scan tool.

1. Turn OFF the ignition for 30 seconds.
2. Measure the resistance from the reference ground circuit of the TP sensor to battery ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 23

Go to Step 10

10 |

1. Disconnect the ECM connector.
2. Test the reference ground circuit of the TP sensor for an open or high resistance.
3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 11

11 | Measure the resistance from the case of the ECM to battery ground. Does the resistance measure less than the specified value? | 5 ohms | Go to Step 24 | Go to Step 21
12 |

1. Turn OFF the ignition.
2. Disconnect the APP sensor connector.
3. Turn ON the ignition with the engine OFF.
4. Measure the voltage between the 5 volt reference circuit of the TP sensor and battery ground using the DMM.

Does the voltage measure within the specified value?

4.8-5.2 V

Go to Step 25

Go to Step 13

13 | Is the voltage less than the specified value? | 5 V | Go to Step 15 | Go to Step 14
14 | Test the 5 volt reference circuit of the TP sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 18
15 | Test the 5 volt reference circuit of the TP sensor for a short to ground, a high resistance, or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 19
16 | Test the signal circuit of the TP sensor 2 for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 24
17 |

1. Test the signal circuit of the TP sensor 2 for the following conditions:

• | Short to ground

• | Short to the reference ground circuit

• | High resistance

• | An open circuit

2. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 24

18 | Test the 5 volt reference circuit of the APP sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 24
19 | Test the 5 volt reference circuit of the APP sensor for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 24
20 |

1. Inspect and test ALL of the circuits from the throttle position sensor to the ECM for the following conditions:

• | High resistance

• | Corrosion

• | Loose terminals

• | Poor terminal contact

2. Repair the circuits or connections as necessary. Refer to Wiring Repairs and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 28

Go to Step 23

21 | Repair the open or high resistance in the ECM ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | --
22 | Repair the harness or connectors as necessary. Refer to Wiring Repairs and Connector Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 28 | --
23 | Inspect for poor connections at the harness connector of the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 26
24 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 27
25 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 28 | --
26 | Replace the throttle body assembly. Refer to Throttle Body/Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 28 | --
27 | Important: Perform the Idle Learn Procedure when replacing the ECM or the throttle body. Important: This vehicle is equipped with a theft deterrent system that interfaces with the engine control module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 28

--

28 |

1. Turn OFF the ignition for 30 seconds.
2. Use the scan tool in order to clear the DTCs.
3. Start the engine.
4. Allow the engine to idle until the engine reaches the normal operating temperature.
5. Select DTC and the Specific DTC function.
6. Enter the DTC number that was set.
7. Operate the engine within the Conditions for Running this DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 29

Go to Step 2

29 | Does the scan tool display any additional, undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK