GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The control modules on this vehicle 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 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