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

When the low beam is activated and the turn signal/multi-function switch is placed in the high beam position, the body control module (BCM) will receive a ground signal through the turn signal/multi-function switch signal circuit to illuminate the high beam lamps.

Conditions for Running the DTC

Low beam is ON and high beam is activated

Conditions for Setting the DTC

The BCM reports stuck turn signal/multi-function switch.

Action Taken When the DTC Sets

The BCM will not attempt to switch ON the high beam lamps.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

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 Views)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
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, headlamp low beams ON, turn the high beam lamps ON and OFF using the turn signal/multifunction switch. The high beam lamps should turn ON and OFF when changing between the selected states.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the S78 Turn Signal/Multi-Function Switch.
2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the ground circuit terminal 6 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool High Beam Select Switch parameter is Inactive.

• If not the specified value, test the signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the K9 BCM.

4. Install a 3 A fused jumper wire between the signal circuit terminal 11 and the ground circuit terminal 6. Verify 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.

5. If all circuits test normal, test or replace the S78 Turn Signal/Multi-Function Switch.

Component Testing

Flash to Pass Switch Test
1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multi-function switch.
2. Test for infinite resistance between the signal terminal 12 and the ground terminal 6 with the switch in the open position.

• If not the specified value, replace the S78 turn signal/multi-function switch.

3. Test for less than 5 ohm between the signal terminal 12 and the ground terminal 6 with the switch in the closed position.

• If greater than the specified range, replace the S78 turn signal/multi-function switch.

High Beam Switch Test
1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multi-function switch.
2. Test for infinite resistance between the signal terminal 11 and the ground terminal 6 with the switch in the open position.

• If not the specified value, replace the S78 turn signal/multi-function switch.

3. Test for less than 5 ohm between the signal terminal 11 and the ground terminal 6 with the switch in the closed position.

• If greater than the specified range, replace the S78 turn signal/multi-function 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, setup and programming