GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 Savana 🢒 Engine 🢒 Engine Electrical 🢒 DTC B1327

Circuit Description

The module has an internal voltage sensor with a dedicated circuit that checks the battery positive voltage and battery negative circuit voltage to determine if it is between 9-15.9 volts.

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 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 via class 2 and may illuminate the charge indicator.

Conditions for Clearing the MIL/DTC

In order to clear the DTC from a current status the voltage shall be greater than 9.54 volts for 2 seconds.

DTC may be cleared with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Tests for the proper operation of the complete circuit.

    2.

  2. Tests for the proper operation of the battery positive voltage circuit.

Step

Action

Value

Yes

No

Schematic Reference: Body Control System Schematics in Computer/Integrating Systems

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

1

Did you perform the Diagnostic System Check - Keyless Entry?

--

Go to Step 2

Go to Diagnostic System Check - Remote Keyless Entry in Vehicle DTC Information

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Volts parameter in the Body Control Module (BCM) data list.

Does the scan tool indicate the battery voltage is greater than the specified value?

9.5 V

Go to Step 7

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the affected module.
  3. Measure the voltage from the battery positive voltage circuit of the module and the ground circuit of the module.

Does the voltage measure near or above the specified value?

9.5 volts

Go to Step 7

Go to Step 4

4

Measure the voltage from the battery positive voltage circuit of the module to a known good ground.

Does the voltage measure near the specified value?

B+

Go to Step 6

Go to Step 5

5

Test the battery positive voltage circuit of the module 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 9

Go to Step 7

6

Test the ground circuit of the module 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 9

Go to Step 8

7

Inspect for poor connections at the harness connector of the module. 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 9

Go to Step 8

8

Replace the affected module.

Did you complete the replacement?

--

Go to Step 9

--

9
  1. Use the scan tool in order to clear the DTC.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK