GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC 68

Circuit Description

The electronic brake control module (EBCM) constantly monitors the throttle position as read by the throttle position (TP) sensor and compares it with the throttle position set by the accelerator and servo control module (ASM).

Conditions for Running the DTC

DTC 68 can be set anytime the ignition switch is in the ON position.

Conditions for Setting the DTC

The EBCM throttle position inputs do not correlate with each other.

Action Taken When the DTC Sets
    • The EBCM disables the traction control system for the duration of the ignition cycle.
    • The TRAC OFF warning indicator turns ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.

Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.

The following are possible causes of the malfunction:

    • An powertrain control module (PCM) fault is current
    • An internal EBCM malfunction
    • An internal ASM malfunction

If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step tests the throttle request circuit of the ASM.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform A Diagnostic System Check - ABS?

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Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to read the powertrain control module (PCM) DTCs.

Are there any PCM DTCs?

--

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 5.7L

Go to Step 3

3

  1. Turn ON the ignition.
  2. Measure the voltage of the accelerator and servo control module (ASM) throttle request circuit by backprobing the ASM harness connector. Refer to Circuit Testing in Wiring Systems.
  3. Observe the voltage reading while varying the position of the throttle.

Does the voltage measure as specified?

Throttle closed -- Approximately 1 V

Throttle wide open -- Approximately 10 V

Go to Step 4

Go to Step 5

4

Replace the electronic brake control module (EBCM). Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

--

Go to Step 6

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5

Replace the ASM. Refer to Accelerator and Servo Control Module Replacement .

Did you complete the replacement?

--

Go to Step 6

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6
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK