GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The BCM stores calibrations in an EEPROM (Electronically Erasable Programmable Read Only Memory). When the ignition switch is first turned on, the BCM performs internal tests on the EEPROM and can determine the integrity of its non-volatile memory. The BCM compares its previously stored checksum with checksum calculated When the ignition switch is first turned on. If the two checksums do not match, the BCM will indicate a calibration malfunction (checksum error) is present.

Conditions for Setting the DTC

    • The stored checksum does not match the calculated checksum.
    • The BCM detects an internal memory (checksum error) malfunction.
    • The condition must occur when the ignition switch is first turned on.

Action Taken When the DTC Sets

The BCM stores DTC B0605 in memory.

Conditions for Clearing the DTC

    • The BCM no longer detects an internal memory (checksum error) malfunction.
    • A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
    • Using a scan tool.

Diagnostic Aids

DTC B0605 is related to an internal malfunction of the EEPROM in the BCM. The EEPROM is not removable from the BCM; therefore, replace the BCM. A service replacement BCM must be programmed and configured to the vehicle. Use the scan tool in order to make sure the BCM is properly programmed and configured for the correct Passlock and vehicle option content. Refer to Body Control Module (BCM) Programming/RPO Configuration for more information.

Test Description

The number below refers to the step number(s) on the diagnostic table.

  1. Determines whether the condition is intermittent or the BCM is faulty.

Step

Action

Value(s)

Yes

No

1

Was the BCM Diagnostic System Check performed?

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Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. Clear BCM DTCs. Refer to Clearing DTCs for more information.
  2. Turn the ignition switch off.
  3. Wait 10 seconds.
  4. Turn the ignition switch on.
  5. Check for BCM DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying for more information.

Does BCM DTC B0605 reset as a current DTC?

--

Go to Step 3

Go to Step 4

3

  1. Replace the BCM. Refer to Body Control Module Replacement for more information.
  2. After replacing the BCM, perform the Setup New BCM procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration for more information.

Is the repair complete?

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Go to Step 5

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4

The malfunction is not present at this time. Refer to Diagnostic Aids for more information regarding this DTC.

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5

  1. Turn the ignition switch off.
  2. Reinstall connectors/components removed.
  3. Turn the ignition switch on.
  4. Clear the BCM DTCs. Refer to Clearing DTCs for more information.
  5. Check for BCM DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying for more information.

Are there any BCM current DTCs set?

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Go to Diagnostic System Check - Body Control System

System OK