GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 DTS 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B2585

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 B2585 00: Left Parklamp Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Park Lamp Relay Control

1

1

B2585 00

--

1. Park, License, and/or Tail Lamps Malfunction

Circuit/System Description

All Countries Except Japan, Korea, Taiwan

Voltage is applied at all times to the PRK LAMP relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch ON signal circuit to the body control module (BCM). The BCM then applies a ground to the park lamp relay control circuit. This energizes the relay and applies voltage through both PRK LAMP fuses and the park lamp supply voltage circuits illuminating the park, tail, and license lamps.

Japan, Korea, Taiwan Only

Voltage is applied at all times to the PRK LAMP relay and the RT PRK LAMP relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch signal circuit to the BCM. The BCM then applies a ground to both the park lamp relay control circuits. This energizes the relays and applies voltage through both PRK LAMP fuses and the park lamp supply voltage circuits illuminating the park, tail, and license lamps.

Conditions for Running the DTC
    • Battery voltage must be between 9-16 volts.
    • Park lamps ON.

Conditions for Setting the DTC

DTC B2585 00 will set when the BCM detects a short to voltage in the park lamp relay control circuit.

Action Taken When the DTC Sets

When DTC B2585 00 is present, the park lamps will not operate.

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

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing
  1. Ignition OFF, remove the appropriate PRK LAMP Relay or RT PRK LAMP relay from the rear fuse block.
  2. Connect a test lamp between B+ and the appropriate control circuit terminal listed below.
    3. • Control terminal 101
    • Control terminal 92 - Japan, Korea, Taiwan only
  3. Ignition ON, command the Parking Lamps 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, test or replace the park lamp relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Relay Replacement
    •  Control Module References for BCM replacement, setup, and programming