GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Yukon XL - 4WD 🢒 Body and Accessories 🢒 Lighting Systems 🢒 DTC B1480

Circuit Description

CTSY LP fuse in the body wiring harness junction box supplies battery positive voltage to the coil side, and the switch side of the inadvertent power relay. The body control module (BCM) provides ground to the inadvertent power relay. When the BCM receives a signal to turn on the courtesy lamps the BCM energizes the inadvertent power relay. Currant flow is from the inadvertent power relay to the courtesy lamp relay and to the BCM, which then energizes the courtesy lamps relay. The battery rundown protection function allows the BCM to disable the courtesy lamps, the cargo lamps and the underhood lamp 40 minutes after the ignition switch is turned OFF. The BCM monitors the output of the inadvertent power relay on the courtesy lamps supply voltage circuit.

Conditions for Running the DTC

The system voltage must be between 9.0 and 16.0 volts.

Conditions for Setting the DTC
    •  When the BCM commands the inadvertent power relay on, and receives no voltage on the courtesy lamps supply voltage circuit at the BCM, DTC B1480 will set.
    • The above conditions must be met for 0.5 seconds.

Action Taken When the DTC Sets

The following lamps will be disabled:

    • The courtesy/dome
    • The IP compartment
    • The reading
    • The underhood
    • The vanity
    • The cargo

Conditions for Clearing the DTC
    • This DTC will clear on current status after the condition for setting the fault is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • A scan tool may be used to clear history and current DTCs.

Diagnostic Aids
    • Perform a visual inspection for loose or poor connections at all related components.
    • Check for an open in CKT 40 or an open CTSY LP fuse.

Test Description

The number(s) below refer to the step number(s) 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. Tests for voltage at the battery positive voltage circuit, coil side, of the inadvertent power relay. The CTSY LP fuse supplies voltage to the coil side of the inadvertent power relay.

    3.

  3. Verifies that the body control module is providing ground to the inadvertent power relay.

    4.

  4. Tests if ground is constantly being 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

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

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 Step 8

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the inadvertent power relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit, coil side, of the inadvertent power relay and a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 11

4

  1. Connect a test lamp between the courtesy lamp control circuit of the inadvertent power relay and the battery positive voltage circuit, coil side, 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 9

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 courtesy lamp relay 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 14

Go to Step 10

7

Test the courtesy lamp relay 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 14

Go to Step 10

8

Test the courtesy lamps supply voltage circuit between the body control module and the inadvertent power relay for a high resistance or an open.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

9

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 14

Go to Step 12

10

Inspect for poor connections at the harness connector of the body control 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 14

Go to Step 13

11

Repair the battery positive voltage circuit of the inadvertent power relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

12

Replace the inadvertent power relay.

Did you complete the replacement?

Go to Step 14

--

13

Important: Perform the setup procedure for the body control module.

Replace the body control module. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 14

--

14
  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