GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Blazer - 2WD 🢒 DTC 🢒 DTC B1480

Circuit Description

The battery rundown protection function allows the body control module (BCM) to disable the courtesy lamps, instrument panel (I/P) compartment lamp and the underhood lamp 20 minutes after the ignition switch is turned OFF. The BCM monitors the output of the inadvertent power relay and the inadvertent power relay control circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1480 Battery Rundown Voltage High

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC
    •  When the inadvertent power relay control circuit is shorted to ground.
    • When there is an open or short to battery voltage on the inadvertent power relay ground circuit.
    • An open CTSY fuse or open in the battery supply circuit to the inadvertent power relay.
    • The above conditions must be met for 0.5 seconds.

Action Taken When the DTC Sets

The following lamps will be disabled:

    • The dome lamp
    • The glove box lamps
    • The reading lamps if equipped
    • The underhood lamp
    • The vanity mirror lamps if equipped

Conditions for Clearing the MIL/DTC
    • The conditions for setting the DTC are no longer present.
    • A history DTC will clear after 40 malfunction free ignition cycles.
    • The powertrain control module (PCM) receives the clear code command from the scan tool.

Diagnostic Aids

Check for an open in battery feed circuit to the inadvertent power relay or an open CTSY LP fuse. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. Listen for an audible click when the inadvertent power relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. This step tests for voltage at the coil side of the inadvertent power relay. The CTSY fuse supplies power to the coil side of the inadvertent power relay.

    3.

  3. This step verifies that the BCM is providing ground to the inadvertent power relay.

    4.

  4. This step tests if a ground is constantly applied to the inadvertent power relay.

    5.

  5. Since this is a general circuit malfunction code, it is necessary to test for both a short to voltage as well as an open on this circuit.

Step

Action

Yes

No

Schematic Reference: Power Distribution Schematics in Wiring Systems

Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the inadvertent power relay ON and OFF.

Does the inadvertent power relay turn ON and OFF with each command?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the inadvertent power relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side feed circuit of the inadvertent power relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

  1. Connect a test lamp between the control circuit of the inadvertent power relay and the coil side feed circuit of the inadvertent power relay.
  2. With a scan tool, command the inadvertent power relay ON and OFF .

Does the test lamp turn ON and OFF with each command?

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each command?

Go to Step 7

Go to Step 6

6

Test the control circuit of the inadvertent power relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the control circuit of the inadvertent power relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

Inspect for poor connections at the inadvertent power relay. 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 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the body control module (BCM). 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 13

Go to Step 12

10

Repair the coil side feed circuit of the inadvertent power relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the inadvertent power relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 13

--

12

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

Did you complete the replacement?

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs .
  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