GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The control modules on this vehicle monitor vehicle system voltage through the battery positive voltage circuits. Damage to components, and incorrect data can occur if the voltage is out of range.This vehicle has multiple modules that will set this DTC. For more information on which modules refer to Diagnostic Trouble Code (DTC) List - Vehicle

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1327 Device Power 1 Circuit Low

Conditions for Running the DTC

This DTC shall run only if the module has power, ground, and the ignition is not in START mode. This DTC shall execute regardless of the battery voltage.

Conditions for Setting the DTC

    • This DTC shall be set as current when the voltage falls below 9 volts for 1.2 seconds.
    • When the vehicle exits START, the module shall delay checking the voltage for 2 seconds.

Action Taken When the DTC Sets

    • A message shall be sent out to notify all other modules of low battery voltage.
    • The modules disable the setting of U codes and other DTCs.

Conditions for Clearing the DTC

    • The DTC will clear current status when the voltage is greater than 9.5 volts for 1.2 seconds.
    • A history DTC will clear after 50 consecutive ignition cycles, if the condition for the malfunction is no longer present.
    • Use a scan tool.

Step

Action

Values

Yes

No

Schematic Reference: Starting and Charging Schematics or Power Distribution Schematics in Wiring Systems

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Operate the vehicle within the Conditions for Running DTC B1327.

Does the scan tool indicate that DTC B1327 is current in more than one module?

--

Go to Step 6

Go to Step 3

3

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

Does the voltage measure greater than the specified value?

9.4 V

Go to Step 11

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the BCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the battery positive voltage circuit of the BCM and the ground circuit of the BCM.

Does the voltage measure greater than the specified value?

9.4 V

Go to Step 5

Go to Battery Inspection/Test

5

Measure the voltage between the battery positive voltage circuit of the BCM and a good ground.

Does the voltage measure greater than the specified value?

9.4 V

Go to Step 9

Go to Step 8

6

  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the module setting the DTC B1327.
  3. Measure the voltage between the battery positive voltage circuit of the module setting the DTC B1327 and the ground circuit of the module setting the DTC B1327.

Does the voltage measure greater than the specified value?

9.4 V

Go to Step 10

Go to Step 7

7

Measure the voltage between the battery positive voltage circuit of the BCM or module setting DTC B1327 and a good ground.

Does the voltage measure greater than the specified value?

9.4 V

Go to Step 9

Go to Step 8

8

Test the battery positive voltage circuit of the BCM or module setting DTC B1327 for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

9

Test the ground circuit of the BCM or module setting DTC B1327 for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

10

Inspect for poor connections at the harness connector of the BCM or module setting DTC B1327. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

11

Replace the BCM or module setting DTC B1327. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 12

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12

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

--

Go to Step 3

System OK