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For 1990-2009 cars only

DTC P0120 AWD

Circuit Description

The DTC P0120 Throttle Position (TP) Sensor Circuit diagnostic detects an out of range sensor signal. The TP sensor is a potentiometer whose resistance value changes along with the throttle valve position. The powertrain control module (PCM) provides a 5-volt reference voltage to the TP sensor. The PCM reads the voltage across the TP sensor and uses the voltage to calculate the percentage of throttle valve opening. The TP sensor resistance decreases as the throttle valve opening increases. When the TP sensor resistance decreases the voltage being monitored by the PCM increases. The TP sensor resistance increases when the throttle valve opening decreases, therefore the voltage being monitored by the PCM will decrease.

Throttle Opening

TP Resistance

TP Percentage

TP Signal Voltage

Large

High

High

High

Small

Low

Low

Low

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0120 Throttle Position (TP) Sensor Circuit

Conditions for Running the DTC

    • The ignition is ON or the engine is running.
    • DTC P0120 runs continuously once the above condition has been met.

Conditions for Setting the DTC

    • The TP sensor input to the PCM is less than 0.1 volt.
        OR
    • The TP sensor input to the PCM is more than 4.9 volts.
    • Either of the above conditions is present for at least 5 seconds.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL).
    • The PCM stores the conditions that were present when the DTC set as Freeze Frame data.
    • The TP sensor angle will default to 0 percent.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the MIL on the third consecutive trip in which the diagnostic runs without a fault.
    • The PCM clears a History DTC after 40 consecutive warm-up cycles without a fault.
    • You use the scan tool Clear DTC Information function.

Diagnostic Aids

    • On a good TP sensor the scan tool will typically display a TP angle of 8-10 percent at idle, and 76-77 percent at wide open throttle (WOT).
    • An intermittent malfunction may be caused by fault in the TP sensor electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
    • Repair any electrical circuit faults that were found. Refer to Wiring Repairs .
    • The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

Test Description

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

  1. The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step determines if DTC P0120 is the result of a hard failure or an intermittent condition.

  3. When the 5-volt reference is jumpered to the TP input circuit, the scan tool parameter should read 99 percent.

  4. When the TP sensor input circuit is jumpered to battery voltage, the scan tool parameter should read 99 percent.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle .

2

With the throttle closed, select the TP sensor parameter on the scan tool.

Is the TP sensor percentage within the specified value?

7-11%

Go to Step 3

Go to Step 4

3

  1. Perform the scan tool Clear DTC Information function.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Freeze Frame conditions as specified.

Does DTC P0120 set?

--

Go to Step 4

Go to Diagnostic Aids

4

Is a DTC P0110 or DTC P0115 also set?

--

Go to Step 13

Go to Step 5

5

Observe the throttle position (TP) sensor with the throttle closed.

Is the TP sensor percentage near the specified value?

99%

Go to Step 10

Go to Step 6

6

Observe the TP sensor with the throttle closed.

Is the TP sensor percentage less than the specified value?

2%

Go to Step 7

Go to Diagnostic Aids

7

  1. Disconnect the TP sensor electrical connector.
  2. Jump the 5-volt reference circuit and the TP sensor input circuit together at the TP sensor harness connector.
  3. Select the TP sensor on the scan tool.

Is the TP sensor percentage more than the specified value?

90%

Go to Step 16

Go to Step 8

8

  1. Connect a test lamp between battery voltage and the TP sensor input circuit at the TP sensor harness connector.
  2. Observe the TP sensor on the scan tool.

Is the TP sensor percentage more than the specified value?

90%

Go to Step 9

Go to Step 14

9

  1. Test the 5-volt reference circuit for an open.
  2. Repair as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 18

10

  1. Disconnect the TP sensor electrical connector.
  2. Observe the TP sensor on the scan tool.

Is the TP sensor percentage at the specified value?

0%

Go to Step 11

Go to Step 12

11

Connect a test lamp to B+ and the ground circuit of the TP sensor.

Did the test lamp illuminate?

--

Go to Step 17

Go to Step 15

12

  1. Test for a short to voltage in the TP sensor input circuit.
  2. Repair as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 19

13

  1. Test for an open in the TP sensor ground circuit between SP108 and the powertrain control module (PCM).
  2. Repair as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 18

14

  1. Test the TP sensor input circuit for an open or a short to ground.
  2. Repair the circuit as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 18

15

Repair the open in the TP sensor ground circuit between the sensor and SP108. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 20

--

16

  1. Test for an intermittent or a poor electrical connection at the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
  2. Repair as necessary.

Did you find and repair a condition?

--

Go to Step 20

Go to Step 17

17

Replace the TP sensor. Refer to Throttle Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 20

--

18

  1. Test for an intermittent or a poor electrical connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
  2. Repair as necessary.

Did you find and repair a condition?

--

Go to Step 20

Go to Step 19

19

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

20

  1. Use the 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 21

Go to Step 2

21

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 - Vehicle .

System OK

DTC P0120 FWD

Circuit Description

The DTC P0120 Throttle Position (TP) Sensor 1 Circuit diagnostic detects an out of range sensor signal. The TP sensor  1 output provides the powertrain control module (PCM) with a signal voltage that is proportional to the throttle plate movement. The TP sensor used with the throttle actuator control (TAC) system is actually a Hall Effect switch. The Hall Effect switch is surrounded by a magnetic yoke that induces a flux in the magnetic field when the throttle shaft is rotated. The PCM provides a 5-volt reference voltage to the sensor circuits in the TAC module. An integrated circuit (IC) receives and converts the magnetic pulses into two separate TP signal, each with their own characteristics. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. TP sensor 1 determines the actual throttle valve position. TP sensor 2 has a voltage that is more than twice that of TP sensor 1 at idle. TP sensor 2 provides a backup value for TP sensor 1.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0120 Throttle Position (TP) Sensor 1 Circuit

Conditions for Running the DTC

    • The ignition is ON or the engine is running.
    • DTC P0120 runs continuously once the above condition has been met.

Conditions for Setting the DTC

    • The TP sensor 1 input to the PCM is less than 0.2 volt.
        OR
    • The TP sensor 1 input to the PCM is more than 4.5 volts.
    • Either of the above conditions is present for at least 2 seconds.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL).
    • The PCM stores the conditions that were present when the DTC set as Freeze Frame data.
    • The engine will operate in the reduced power mode and the TP sensor angle will default to 19 percent.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the MIL on the third consecutive trip in which the diagnostic runs without a fault.
    • The PCM clears a History DTC after 40 consecutive warm-up cycles without a fault.
    • You use the scan tool Clear DTC Information function.

Diagnostic Aids

    • On the scan tool a good TP sensor 1 will typically display a TP angle of 8-10 percent at idle, and 76-77 percent at wide open throttle (WOT).
    • An intermittent malfunction may be caused by fault in the TAC module electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
    • Repair any electrical circuit faults that were found. Refer to Wiring Repairs .
    • The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

Test Description

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

  1. The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step determines if DTC P0120 is the result of a hard failure or an intermittent condition.

  3. When the 5-volt reference is jumpered to the TP sensor 1 input circuit, the scan tool parameter should read 99 percent.

  4. When the TP sensor 1 input circuit is jumpered to battery voltage, the scan tool parameter should read 99 percent.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

With the throttle closed, select the TP sensor parameter on the scan tool.

Is the TP sensor percentage within the specified value?

7-16%

Go to Step 3

Go to Step 4

3

  1. Perform the scan tool Clear DTC Information function.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Freeze Frame conditions as specified.

Does DTC P0120 set?

--

Go to Step 4

Go to Diagnostic Aids

4

Is a DTC P0453 also set?

--

Go to Step 13

Go to Step 5

5

Observe the throttle position (TP) sensor with the throttle closed.

Is the TP sensor percentage at the specified value?

99%

Go to Step 10

Go to Step 6

6

Observe the TP sensor with the throttle closed.

Is the TP sensor percentage less than the specified value?

2%

Go to Step 7

Go to Diagnostic Aids

7

  1. Disconnect the throttle actuator control (TAC) module electrical connector.
  2. Jump the 5-volt reference circuit and the TP sensor input circuit together at the TAC module harness connector.
  3. Select the TP sensor on the scan tool.

Is the TP sensor percentage more than the specified value?

90%

Go to Step 16

Go to Step 8

8

  1. Connect a test lamp between battery voltage and the TP sensor 1 input circuit at the TAC module harness connector.
  2. Observe the TP sensor on the scan tool.

Is the TP sensor percentage more than the specified value?

90%

Go to Step 9

Go to Step 14

9

  1. Test the 5-volt reference circuit for an open.
  2. Repair as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 18

10

  1. Disconnect the TAC module electrical connector.
  2. Observe the TP sensor on the scan tool.

Is the TP sensor percentage at the specified value?

0%

Go to Step 11

Go to Step 12

11

Connect a test lamp to B+ and the ground circuit of the TP sensor.

Did the test lamp illuminate?

--

Go to Step 17

Go to Step 15

12

  1. Test for a short to voltage in the TP sensor 1 input circuit.
  2. Repair as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 19

13

  1. Test for an open in the TP sensor ground circuit between SP108 and the powertrain control module (PCM).
  2. Repair as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 18

14

  1. Test the TP sensor 1 input circuit for an open or a short to ground.
  2. Repair the circuit as necessary. Refer to Wiring Repairs .

Did you find and repair a condition?

--

Go to Step 20

Go to Step 18

15

Repair the open in the TP sensor 1 ground circuit between the TAC module and SP108. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 20

--

16

  1. Test for an intermittent or a poor electrical connection at the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
  2. Repair as necessary.

Did you find and repair a condition?

--

Go to Step 20

Go to Step 17

17

The TP sensor in the TAC module is faulty. Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .

Did you complete the replacement?

--

Go to Step 20

--

18

  1. Test for an intermittent or a poor electrical connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
  2. Repair as necessary.

Did you find and repair a condition?

--

Go to Step 20

Go to Step 19

19

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 20

--

20

  1. Use the 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 21

Go to Step 2

21

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 - Vehicle .

System OK