GM Service Manual Online
For 1990-2009 cars only

Object Number: 600643  Size: MF
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Engine Controls Components
Power and Ground
OBD II Symbol Description Notice

Circuit Description

This diagnostic will detect a loss of serial communication from the electronic brake control module (EBCM) to the control module. This serial communication is essential in order to distinguish misfire from a rough road condition.

Conditions for Running the DTC

    • The vehicle speed is more than 2 km/h (1 mph).
    • The engine speed is less than 5,800 RPM.
    • The engine load is less than 89 percent.
    • Engine misfire is detected.

Conditions for Setting the DTC

A serial data malfunction is preventing the vehicle control module (VCM) from receiving rough road detection data.

Action Taken When the DTC Sets

The malfunction indicator lamp (MIL) will not be illuminated and a history DTC is stored.

Conditions for Clearing the MIL/DTC

    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles.
    • A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle.
    • Use the scan tool Clear Information function.

Diagnostic Aids

Inspect for intermittents.

An intermittent may be caused by any of the following conditions:

    • A poor connection
    • Rubbed through wire insulation
    • A broken wire inside the insulation

Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Test Description

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

  1. This step isolates an open serial data circuit from the EBCM system.

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Disconnect the VCM and EBCM.
  2. Inspect the serial data circuit between the VCM and the EBCM for an open.

Was a problem found?

--

Go to Step 3

Go to Diagnostic System Check in Antilock Brake System

3

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 4

--

4

  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches a normal operating temperature.
  4. Select the DTC and the Specific DTC functions.
  5. Enter the DTC number which was set.
  6. Operate the vehicle within the Conditions for Setting the DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate that the diagnostic Passed?

--

Go to Step 5

Go to Step 2

5

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the Applicable DTC Table

System OK