GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 DTS 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC B2590

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B2590 00: Left Cornering Lamp Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Left Cornering Lamp Control

2

1

B2590 00

--

  1. Cornering Lamps Inoperative
  2. Cornering Lamps Always On

Circuit/System Description

Battery voltage is applied at all times to the left front cornering lamp PCB relay which is part of the underhood fuse block. When the turn signal switch is placed in the left turn position, ground is applied through the left turn signal switch signal circuit to the body control module (BCM) The BCM then applies a ground to the left cornering lamp relay control circuit energizing the relay. With the relay energized, battery voltage is applied through the switch side of the relay, the LF CRN LAMP Fuse, and the left front cornering lamp supply voltage circuit to the left front cornering lamp.

Conditions for Running the DTC
    • The ignition must be ON.
    • The park or headlamps must be ON.
    • The left turn signal must be ON.
    • The cornering lamp must be commanded on by the BCM.

Conditions for Setting the DTC

The BCM detects a short to voltage on the left cornering lamp relay control circuit while trying command the cornering lamp ON.

Action Taken When the DTC Sets

The BCM will deactivate the cornering lamp relay for the remainder of the ignition cycle.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction ignition cycles have occurred.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing
  1. Ignition OFF, disconnect the (C2) harness connector at the underhood fuse block.
  2. Connect a test lamp between battery voltage and the control circuit terminal 3.
  3. Ignition ON, command the Left Cornering Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    4. ⇒ If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If the circuit tests normal, replace the underhood fuse block.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Underhood Electrical Center or Junction Block Replacement
    •  Control Module References for BCM replacement, setup, and programming