GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2004 🢒 Century 🢒 DTC 🢒 DTC B2559

Circuit Description

The Body Control Module (BCM) receives an ground from the courtesy lamp ground circuit. The sole purpose of this input is to provide a ground path for all of the courtesy lamps controlled through the courtesy lamp low control circuit.

Conditions for Running the DTC

If the input does not match a normal ground potential.

Conditions for Setting the DTC
    • The BCM detects a open when a ground is expected.
    • The condition above must be present for more than 0.3 seconds

Action Taken When the DTC Sets

The BCM stores DTC B2559 in memory.

Conditions for Clearing the DTC
    • A current DTC B2559 will clear if the open is no longer detected by the BCM.
    • A history DTC B2559 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present nor any other malfunction in the BCM is detected.
    • The BCM receives a clear code command from the scan tool.

Diagnostic Aids
    • If the DTC B2559 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • The following conditions may cause an intermittent malfunction to occur:
       - An intermittent open in the theater dimming ground circuit.
       - The BCM is intermittently opened.

Test Description

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

  1. Checks for an open in the courtesy lamps ground circuit.

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics

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

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2
  1. Turn ON the ignition, with the engine off.
  2. With the I/P dimmer switch, turn the interior lamps ON.

Do the interior lamps turn ON?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the BCM connector.
  3. Using a test lamp that is connected to battery positive voltage, probe the ground circuit of the BCM that provides a ground path for the courtesy lamps low control circuit.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

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 7

Go to Step 6

5

Repair the open or high resistance in the courtesy lamps ground circuit of the BCM that provides a ground path for the courtesy lamps low control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 7

--

6

Important: Perform the set up procedure for the Body Control Module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 7

--

7
  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