Buick Regal: 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
High Beam and Headlamp Flash Select Circuit Malfunction
Diagnostic Fault Information
1. Headlamps Malfunction
2. Park, License, and/or Tail Lamps Malfunction
Circuit/System Description
When the turn signal/multifunction switch is momentarily placed in the flash
to pass position, ground is
applied to the body control module (BCM) through the flash to pass signal
circuit. The BCM responds to
the flash to pass request by applying ground to the high beam relay control
circuit which energizes the
high beam relay. With the high beam relay energized, the switch contacts close
allowing battery voltage
to flow through the high beam fuses to the high beam control circuits
illuminating the high beam
headlamps. The high beam headlamps will only illuminate for as long at the flash
to pass switch is
activated.
Conditions for Running the DTC
Battery voltage must be between 9-16 V.
Conditions for Setting the DTC
The BCM detects a short to ground in the turn signal/multifunction switch
flash to pass signal circuit.
Actions Taken When the DTC Sets
The high beam headlamps and the high beam indicator on the instrument cluster
are always ON.
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
Headlights/Daytime Running Lights (DRL) Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
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, scan tool disconnected, all doors closed, all accessories
OFF, open and close drivers
door, disconnect the harness connector at the S78 Turn Signal/Multifunction
Switch. It may take
up to 2 min for all vehicle systems to power down.
2. Test for less than 15 Ω between the ground circuit terminal 3 and ground.
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 15 Ω
3. Ignition ON.
4. Verify the scan tool Headlamps Flash Switch parameter is Inactive.
- Ignition OFF, disconnect the X3 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal circuit terminal 6 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K9 Body Control Module.
- Go to next step: If Inactive
5. Install a 3 A fused jumper wire between the signal circuit terminal 6 and
ground.
6. Verify the scan tool Headlamps Flash Switch parameter is Active.
- Ignition OFF, disconnect the X3 harness connector at the K9 Body Control
Module, ignition
ON.
- Test for less than 1 V between the signal circuit terminal 6 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
- Go to next step: If Active
7. Test or replace the S78 Turn Signal/Multifunction Switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Turn Signal Switch Replacement
- Control Module References for BCM replacement, programming, and setup
READ NEXT:
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.
Diag
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.
Diag
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.
Diag
SEE MORE:
Removal Procedure
1. Remove the tire and wheel assembly.
WARNING: To prevent personal injury and/or component damage, do not
allow the weight
of the vehicle to load the front wheels, or attempt to operate the vehicle, when
the wheel drive shaft(s) or wheel drive shaft nut(s) are removed. To do so m
NOTE:
The Lane Keep Assist system DOES NOT continuously steer the
vehicle
The Lane Keep Assist system replaces Lane Departure Warning
System
Lane Departure Warning will have more alerts than Lane Keep
Assist (visual, audible, and haptic warning
The system assists driver to keep vehicle in-la