B3650
DTC B3650
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 B3650 08
- High Beam Request Signal Circuit Performance - Signal Invalid
Diagnostic Fault Information
Circuit/System Description
The BCM monitors the voltage level within the high beam signal circuit and the flash to pass signal circuit. When the turn signal/multifunction switch is moved to the high beam position or to the flash to pass position, the voltage within the appropriate signal circuit drops to less than 1 V. The BCM will detect the voltage drop and will command the headlamp high beams to turn ON or OFF.
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 headlamp high beam signal circuit.
Action Taken When the DTC Sets
The high beam headlamps will malfunction.
Conditions for Clearing the DTC
* The DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 50 ignition cycles.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
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, observe the scan tool High Beam Select Switch parameter while pulling and releasing the turn signal/multi-function switch. The value should change between Inactive and Active when changing between the selected states.
Circuit/System Testing
1. Ignition OFF, disconnect at the S78 turn signal/multifunction switch.
2. Ignition ON, verify that the scan tool High Beam Select Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K9 BCM.
3. Connect a 3 A fused jumper wire between the signal circuit terminal 2 and ground, verify that the scan tool High Beam Select Switch parameter is Active.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
4. If all circuits test normal, test or replace the S78 turn signal/multifunction switch.
Component Testing
Turn Signal/Multifunction Switch Test
1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multifunction switch.
2. Test for Infinite resistance between the terminals listed below with the switch in the open position.
* Signal terminal 2 and ground terminal 3
* Signal terminal 4 and ground terminal 3
• If not the specified value, replace the S78 turn signal/multifunction switch.
3. Test for less than 2 ohm between the signal terminal 2 and the ground terminal 3 with the switch in the high beam position.
• If greater than the specified value, replace the S78 turn signal/multifunction switch.
4. Test for less than 2 ohm between the signal terminal 4 and the ground terminal 3 while holding the switch in the flash to pass position.
• 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.
* Turn Signal Multifunction Switch Replacement (Turn Signal Multifunction Switch Replacement)
* Control Module References (Programming and Relearning)for BCM replacement, programming and setup