GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The control modules monitor the battery voltage through the battery positive voltage circuits.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1325 Device Power 1 Circuit

This vehicle has DTCs that include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description.

DTC Symptom

DTC Symptom Descriptor

03

Voltage Below Threshold

07

Voltage Above Threshold

Conditions for Running the DTC

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

Conditions for Setting the DTC

B1325 03

The control module detects a system voltage below 9 volts and the condition is present at least 5 seconds.

B1325 07

The control module detects a system voltage above 18 volts and the condition is present at least 5 seconds.

Action Taken When the DTC Sets

    • The control module immediately disables all outputs when a high voltage condition is detected, with the exception of GMLAN and Run/Crank relay that are 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: Computer/Integrating Systems 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 Voltage Signal parameter in the data list of the module setting the DTC.

Is the Battery Voltage Signal 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 harness connector of the module setting the DTC.
  2. Measure the voltage between the battery positive voltage circuit at the module 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 the following:

    • A short to ground
    • An open
    • A high resistance

Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 9

Go to Battery Inspection/Test

6

Test all ground circuits of the module for an open or high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 7

7

Inspect for poor connections at the harness connector of the affected module. 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 affected module. 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?

--

System OK

Go to Step 2