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DTC B3806

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 B3806 00: Main Beam and Headlamp Flash Select Circuit Malfunction

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Main Beam and Headlamp Flash Select Signal

B3806 00

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Circuit/System Description

When the turn signal/multifunction switch is placed in the high beam or flash to pass position, the body control module (BCM) will receive a ground signal through the turn signal/multifunction switch signal circuit to illuminate the high beam lamps.

Conditions for Running the DTC

High beam or flash activated.

Conditions for Setting the DTC

The body control module (BCM) reports stuck indicator/multifunction switch.

Action Taken When the DTC Sets

The high beam function is inoperative.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

Exterior Lamps 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 Verification

Ignition ON, turn the headlamp switch in the dipped beam position. Push/pull the indicator/multifunction switch between the ON/OFF position. The main beam lamps should be ON/OFF as the switch is cycled.

Circuit/System Testing
  1. Ignition OFF, disconnect the S78 Turn Signal/Multifunction Switch harness connector. Test for less than 5 Ω between the ground circuit terminal 3 and ground.
    2. ⇒If greater then the specified value, test the ground circuit for an open/high resistance.
  2. Connect the S78 Indicator/Multifunction Switch harness connector.
  3. Disconnect the X3 harness connector at the K9 Body Control Module.
  4. Connect a test lamp between B+ and the signal circuit terminal 17 X3.
  5. Pull the S78 Indicator/Multifunction Switch between the flash and OFF position. The test lamp should turn ON and OFF as the switch is cycled.
    6. ⇒If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the S78 Indicator/Multifunction Switch.
    ⇒If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit test normal, replace the S78 Indicator/Multifunction Switch.
  6. If all circuits test normal, replace the K9 Body Control Module.

Component Testing

Static Test

  1. Ignition OFF, disconnect the S78 Indicator/Multifunction Switch harness connector. S78 Indicator/Multifunction Switch in released position, test for infinite resistance between the terminal 3 and terminal 4.
    2. ⇒If less than the specified value, replace the S78 Indicator/Multifunction Switch.
  2. S78 Indicator/Multifunction Switch in flash position, test for less than 5 Ω between terminal 4 and terminal 3.
    3. ⇒If greater than the specified value, replace the S78 Indicator/Multifunction Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Headlamp Switch Replacement
    •  Indicator Switch Replacement
    • Control Module References for BCM replacement, setup and programming
   


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