GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) monitors the battery voltage through the battery positive voltage circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1325 Device Power 1 Circuit

Conditions for Running the DTC

The voltage supplied to the BCM is in the range of 7-26 volts.

Conditions for Setting the DTC

    • The BCM detects a system voltage below 9 volts or above 18 volts.
    • The above condition is present for at least 5 seconds.

Action Taken When the DTC Sets

    • The BCM immediately disables all outputs when a high voltage condition was detected, with the exception of the ECM/PCM CONT relay that is disabled after a 3 minute delay.
    • The setting of other DTCs is inhibited.

Conditions for Clearing the DTC

    • A current DTC clears when the malfunction is no longer present.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Step

Action

Values

Yes

No

Schematic Reference: Body Control System Schematics

Connector End View Reference: Data Communication 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

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Battery 1 parameter in the body control module (BCM) input data list.

Is the Battery 1 parameter displayed in the specified range?

9-18 V

Go to Step 3

Go to Step 4

3

Is the DTC set as a current DTC?

--

Go to Step 7

Go to Testing for Intermittent Conditions and Poor Connections

4

  1. Disconnect the BCM harness connectors.
  2. Measure the voltage between the battery positive voltage circuit at the BCM harness connector and a good ground.

Is the measured value in the specified range?

9-18 V

Go to Step 6

Go to Step 5

5

Test the battery positive voltage circuit for a short to ground or an open.

Did you find and correct the condition?

--

Go to Step 9

Go to Battery Inspection/Test

6

Test the all of ground circuits of the BCM for an open or high resistance.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 7

7

Inspect for poor connections at the module harness connectors. 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

8

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 9

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9

Operate the system in order to verify the repair.

Did you find and correct the condition?

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System OK

Go to Step 2