GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The throttle position (TP) sensors 1 and 2 are potentiometer type sensors each with three circuits:

    • A 5-volt reference circuit
    • A low reference circuit
    • A signal circuit

The TP sensors are used to determine the throttle plate angle for various engine management systems. The control module provides each TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensors then provide the control module with signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. When the control module detects that TP sensor 1 signal and TP sensor 2 signals disagree or signal voltages are outside the predetermined range, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2135 Throttle Position (TP) Sensor 1-2 Correlation

Conditions for Running the DTC

    • DTCs P2108, or U0107 not set.
    • The ignition switch is in the crank or run position.
    • The ignition voltage is more than 5.23 volts.
    • This diagnostic runs continuously when the above conditions are met.

Conditions for Setting the DTC

    • The TP sensor 2 disagrees with the TP sensor 1 by more than 7.5 percent.
    • The above condition is present for more than 1 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 throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
    • When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests 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. Remember this if you review the stored information in Capture Info.
    • If this DTC is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

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

  1. When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests 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. Remember this if you review the stored information in Capture Info.

Step

Action

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

Is DTC U0107 set?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the Throttle Position (TP) Sensor 1 and 2 Agree/Disagree parameter with a scan tool.

Does the scan tool TP Sensor 1 and 2 Agree/Disagree parameter indicate Disagree?

Go to Step 5

Go to Step 4

4

  1. Remove the air inlet duct from the throttle body.
  2. Disconnect the throttle body harness connector.
  3. Connect the jumper wires between the TP sensor terminals of the throttle body harness connector and the corresponding TP sensor terminals of the throttle body.
  4. Observe the TP sensor 1 and 2 with a scan tool.
  5. Slowly open the throttle blade to wide open throttle (WOT) and back to the closed throttle position several times by hand.

Does the TP Sensor Agree/Disagree parameter change from Agree to Disagree during the above test?

Go to Step 18

Go to Step 20

5

  1. Disconnect the TP sensor harness connector.
  2. Disconnect the throttle actuator control (TAC) module harness connectors.
  3. Test the TP sensor 1, 5-volt reference circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 6

6

Test for a short between the TP sensor 1, 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 7

7

Test the TP sensor 1 signal circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 8

8

Test for a short between the TP sensor 1 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 9

9

Test the TP sensor 1 low-reference circuit for resistance with a DMM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 10

10

Test for a short between the TP sensor 1 low-reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 11

11

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

Did you find and correct the condition?

Go to Step 20

Go to Step 12

12

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 .

Did you find and correct the condition?

Go to Step 20

Go to Step 13

13

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

Did you find and correct the condition?

Go to Step 20

Go to Step 14

14

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 .

Did you find and correct the condition?

Go to Step 20

Go to Step 15

15

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

Did you find and correct the condition?

Go to Step 20

Go to Step 16

16

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

Did you find and correct the condition?

Go to Step 20

Go to Step 17

17

Inspect for an intermittent and for a poor connection at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals .

Did you find and correct the condition?

Go to Step 20

Go to Step 18

18

Inspect for an intermittent and for a poor connection at the harness connector of the throttle body. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals .

Did you find and correct the condition?

Go to Step 20

Go to Step 19

19

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

Did you complete the replacement?

Go to Step 20

--

20

  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.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 21

21

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

System OK