GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The throttle position (TP) sensor incorporates 2 ratiometric TP sensors into one housing. TP sensor 1 and TP sensor 2 each have a 5-volt reference circuit supplied by the throttle actuator control (TAC) module. The TAC module supplies each TP sensor with a low reference circuit. Each TP sensor supplies the TAC module with a signal voltage that is proportional to the throttle blade position. The TP signal voltages are opposite from one another. TP sensor 1 is pulled up to reference voltage as the throttle blade is opened. The TP sensor 2 is pulled down to low reference as the throttle blade is opened. The TP sensor 1 and the accelerator pedal position (APP) sensor 1 share a 5-volt reference circuit that is bussed within the TAC module. The TP sensor 2 and APP sensor 2 share a 5-volt reference circuit that is also bussed within the TAC module. The APP sensor 3 has a dedicated 5-volt reference circuit.

When this DTC sets, the Reduced Engine Power indicator will be displayed.

This DTC incorporates 3 difference diagnostic tests:

    • TP sensor 2 signal circuit voltage out of range
    • Throttle blade minimum position for the TP sensor 2 out of range
    • 5-volt reference of the TP sensor 2 voltage out of range

If the PCM detects one or more of the TP sensor 2 tests are out of range, DTC P0220 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0220 Throttle Position (TP) Sensor 2 Circuit

Conditions for Running the DTC

    • DTCs P2108 or U0107 are not set.
    • The ignition switch in the crank position or the run position.
    • The ignition voltage is greater than 5.23 volts.
    • The TP sensor 2 signal voltage test runs continuously once the above conditions are met.
    • The throttle blade minimum position for the TP sensor 2 test runs once when the ignition is turned ON and the above conditions are met.
    • The 5-volt reference of the TP sensor 2 voltage test runs continuously once the above conditions are met.

Conditions for Setting the DTC

    • TP sensor 2 signal voltage is less than 0.28 volts or more than 4.60 volts for more than 0.1 second.
        OR
    • The TP sensor 2 minimum throttle blade position is more than 4.72 volts or less than 4.19 volts for less than 1 second.
        OR
    • The 5-volt reference circuit of the TP sensor 2 is less than 0.5 volts for more than 0.01 second.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    • The control module commands the TAC system to operate in the Reduced Engine Power mode.
    • A message center or an indicator displays Reduced Engine Power.
    • Under certain conditions the control module commands the engine OFF.

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.

Diagnostic Aids

    • Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
    • When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.
    • If this DTC is determined to be intermittent, refer to Intermittent Conditions .

Test Description

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

  1. Using a test lamp reduces the amount of current fed into the signal circuit. The scan tool should display the maximum value for this parameter, 5 volts even though the actual voltage is higher.

  2. The TP 2 sensor and the APP 2 sensor share a common 5 volt reference. The 5-volt reference circuits are connected internally within the TAC module. Disconnecting the TAC module will isolate the 5-volt reference circuits.

  3. The TP sensor 2 and the APP sensor 2 share a common 5-volt reference. A short to voltage on the APP sensor 2 5-volt reference circuit will affect the TP sensor 2 5-volt reference circuit.

  4. When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This condition is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View References: 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 in Vehicle DTC Information

2

Is DTC P2101, P1516 or U0107 also set?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the air inlet duct from the throttle body assembly.
  3. Disconnect the throttle actuator motor harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Manually close the throttle blade completely while observing the throttle position (TP) sensor 2 voltage parameter on the scan tool.

Does the scan tool indicate that the TP sensor 2 voltage is within the specified values?

4.19-4.72 V

Go to Step 4

Go to Step 7

4

Open the throttle blade to wide open throttle (WOT) by hand while observing the TP sensor 2 voltage parameter on the scan tool.

Does the scan tool indicate TP sensor 2 voltage within the specified values?

0.28-0.81 V

Go to Step 5

Go to Step 7

5

  1. Turn OFF the ignition for 15 seconds.
  2. Reconnect the throttle actuator motor harness connector.
  3. Reinstall the air inlet duct.
  4. Turn ON the ignition with the engine OFF.
  5. Select the DTC Info. option on the scan tool.
  6. Lightly touch and move the related engine wiring harnesses and connectors for the throttle position (TP) sensor while observing the DTC Info. The DTC will set if an intermittent condition is present. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 6

6

  1. Continue to observe DTC Info.
  2. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to the released position 3 times.

Does the scan tool indicate this DTC failed this ignition?

--

Go to Step 26

Go to Diagnostic Aids

7

Observe the TP sensor 2 voltage parameter, with a scan tool.

Does the scan tool indicate that the TP sensor 2 voltage is at the specified value?

5 V

Go to Step 8

Go to Step 12

8

Disconnect the TP sensor harness connector.

Does the scan tool indicate that the TP sensor 2 voltage is at the specified value?

0 V

Go to Step 9

Go to Step 13

9

  1. Disconnect the accelerator pedal position (APP) sensor harness connector.
  2. Turn ON the ignition with the engine OFF.
  3. Test the TP sensor 2 5-volt reference circuit for voltage, with a DMM.

Does the DMM indicate voltage near the specified value?

5 V

Go to Step 10

Go to Step 18

10

With a DMM connected between the TP sensor 1 low reference circuit and the TP sensor 2 low reference circuit at the TP sensor harness connector, test for resistance

Does the DMM indicate resistance within the specified values?

0-5 ohms

Go to Step 14

Go to Step 11

11

  1. Turn OFF the ignition.
  2. Disconnect the throttle actuator control (TAC) module harness connector containing the TP sensor circuits.
  3. Test the TP sensor 2 low reference circuit for an open or for high resistance, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 32

12

  1. Disconnect the TP sensor harness connector.
  2. Connect a test lamp between the TP sensor 2 signal circuit and the battery positive voltage.

Does the scan tool indicate TP sensor 2 voltage near the specified value?

5 V

Go to Step 20

Go to Step 15

13

  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the TP sensor circuits.
  3. Turn ON the ignition.
  4. Test the TP sensor 2 signal circuit for a short to voltage, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 17

14

  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the APP sensor circuits.
  3. Turn ON the ignition with the engine OFF.
  4. Test the APP sensor 2 signal circuit for a short to voltage, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 24

15

  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the TP sensor circuits.
  3. Test the TP sensor 2 signal circuit for an open or for high resistance, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 16

16

Test the TP sensor 2 signal circuit for a short to ground, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 17

17

Test for a short between the TP sensor 2 signal circuit and all other TAC module circuits, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 32

18

  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the TP sensor circuits.
  3. Turn ON the ignition with the engine OFF.
  4. Test the TP sensor 2 5-volt reference circuit for a short to voltage, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 19

19

  1. Turn OFF the ignition.
  2. Disconnect the other TAC module harness connector.
  3. Turn ON the ignition with the engine OFF.
  4. Test the APP sensor 2 5-volt reference circuit for a short to voltage, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 24

20

  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the TP sensor circuits.
  3. Test the TP sensor 2 5-volt reference circuit for an open or for high resistance, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 21

21

Test the TP sensor 2 5-volt reference circuit for a short to ground, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 22

22

  1. Disconnect the APP sensor harness connector.
  2. Disconnect the other TAC module harness connector.
  3. Turn ON the ignition with the engine OFF.
  4. Test the APP sensor 2 signal circuit for a short to voltage, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 23

23

Test the APP sensor 2 5-volt reference circuit for a short to ground, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 24

24

Test the TP sensor 2 5-volt reference circuit for a short to voltage, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 25

25

Test for a short between the TP sensor 2 5-volt reference circuit and all other TAC module circuits, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 26

26

Test for a short between the APP sensor 2 5-volt reference circuit and all other TAC module circuits, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 27

27

Test the TP sensor 2 signal circuit for high resistance, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 28

28

Test the TP sensor 2 low reference circuit for resistance, with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 29

29

  1. Reconnect the TAC module connectors.
  2. Turn ON the ignition.
  3. Measure the voltage at the TP sensor 2 5-volt reference circuit, with a DMM.

Does the DMM indicate voltage greater than the specified value?

6.06 V

Go to Step 32

Go to Step 30

30

  1. Turn OFF the ignition.
  2. Connect a test lamp between APP sensor 2 5-volt reference and battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 32

Go to Step 31

31

Inspect for poor connections at the TP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 33

32

Inspect for poor connections at the TAC module harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 35

Go to Step 34

33

Important: The TP sensor is not a serviceable part and should only be replaced with the throttle body assembly.

Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .

Did you complete the replacement?

--

Go to Step 35

--

34

Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement .

Did you complete the replacement?

--

Go to Step 35

--

35

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.

Does the DTC run and pass?

--

Go to Step 36

Go to Step 2

36

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK