B3806
DTC B3806
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions 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
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 turn signal/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 Lights Schematics Exterior Lights Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Verification
Ignition ON, turn the headlamp switch in the low beam position. Push/pull the turn signal/multifunction switch between the ON/OFF position. The high 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 ohms between the ground circuit terminal 3 and ground.
• If greater then the specified value, test the ground circuit for an open/high resistance.
2. Connect the S78 Turn Signal/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 Turn Signal/Multifunction Switch between the flash and OFF position. The test lamp should turn ON and OFF as the switch is cycled.
• 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 Turn Signal/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 Turn Signal/Multifunction Switch.
6. If all circuits test normal, replace the K9 Body Control Module.
Component Testing
Static Test
1. Ignition OFF, disconnect the S78 Turn Signal/Multifunction Switch harness connector. S78 Turn Signal/Multifunction Switch in released position, test for infinite resistance between the terminal 3 and terminal 4.
• If less than the specified value, replace the S78 Turn Signal/Multifunction Switch.
2. S78 Turn Signal/Multifunction Switch in flash position, test for less than 5 ohms between terminal 4 and terminal 3.
• If greater than the specified value, replace the S78 Turn Signal/Multifunction Switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Headlamp Switch Replacement Service and Repair
* Turn Signal Switch Replacement Turn Signal Switch Replacement
* Control Module References Programming and Relearning for BCM replacement, setup and programming