GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The throttle position (TP) sensor 1 and the TP sensor 2 are potentiometer type sensors. Both sensor types have the following circuits:

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

The TP sensor provides the engine control module (ECM) with a signal voltage proportional to the throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened. When the control module detects that the TP sensor 1 and the TP sensor 2 signal circuits are out of correlation with each other, DTC P2135 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

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

Conditions for Running the DTC

    • The engine is running
    • The ignition voltage is more than 5.25 volts.
    • DTCs P0641 and P0651 are not set.
    • DTC P2135 runs continuously when the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the difference between TP sensor 1 and TP sensor 2 is more than the predicted value for more than 2 seconds.

Action Taken When the DTC Sets

    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

    • 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 non-emission related diagnostic.
    • Clear the DTC with a scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Observe the DTC Information with a scan tool.

Is DTC P0120 or P0220 also set?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the throttle body harness connector.
  3. Disconnect the engine control module (ECM) harness connector.
  4. Measure the resistance of the following circuits for each of the throttle position (TP) sensors with a DMM:
  5. • The low reference circuit
    • The signal circuit
    • The 5-volt reference circuit

Is the resistance more than the specified value for any circuit?

5 ohms

Go to Step 7

Go to Step 4

4

Test the signal circuit of the TP sensor 1 for a short to the signal circuit of the TP sensor 2. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 5

5

Test for an intermittent and for a poor connection at the throttle body harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 6

6

Test for an intermittent and for a poor connection at the ECM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 8

7

Repair the high resistance in the circuit that measured above the specified value. Refer to Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 9

--

8

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

Did you complete the replacement?

--

Go to Step 9

--

9

  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 10

10

Important: Be aware that repairing one individual condition may correct more than one DTC.

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