GM Service Manual Online
For 1990-2009 cars only

Refer to Starting and Charging Schematics and Body Control System Schematics in Body Control Systems.

Circuit Description

The body control module (BCM) monitors the battery voltage. If the battery voltage is higher than the specified range, the BCM sets DTC B1328 as current and turns off certain outputs to prevent damage to internal circuitry.

Conditions for Running the DTC

The ignition switch is on.

Conditions for Setting the DTC

This DTC will set as current when the voltage rises above 18.5 volts for 5 seconds.

Action Taken When the DTC Sets

All of the following BCM outputs are disabled:

    • The dome lamp output
    • The instrument panel dimming lamps output
    • The SECURITY lamp output

Conditions for Clearing the DTC

    • A current DTC B1328 will clear when the battery voltage falls below 18.5 volts.
    • All BCM history codes will clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.

Test Description

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

  1. Tests whether the condition is module, system, or condition related.

  2. Tests whether the condition has been corrected or identified as specified in the supporting text.

Step

Action

Yes

No

1

Did you perform the Charging System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Charging System

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC Information for DTC B3128 in the body control module.

Does the scan tool indicate that DTC B1328 is current?

Go to Step 4

Go to Step 3

3

Since most occurrences of this DTC are caused by jump-starting the vehicle, review with the customer the conditions under which the DTC set.

Did jump-starting the vehicle cause this DTC to set?

Go to Step 2

Go to Step 4

4

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within normal operating conditions.

Does the DTC reset?

Go to Step 5

System OK

5

Inspect the battery voltage and perform the Charging System Check if necessary. Refer to Charging System Check.

Did you find and correct the condition?

System OK

Go to Step 6

6

Important: Perform the set up procedure for the body control module. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the body control module. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

System OK

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