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DTC B3650

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 B3650 08: Main Beam Request Signal Circuit Performance - Signal Invalid

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Indicator/Multifunction Switch Headlamps OFF Signal

B257A 00

1

1

--

Indicator/Multifunction Switch Headlamps ON Signal

B257A 00

1

1

--

Indicator/Multifunction Switch Sidelights ON Signal

2

B257A 00

2

--

Indicator/Multifunction Switch Flash To Pass Signal

3806 00

1

1

--

Indicator/Multifunction Switch Main Beam Signal

B3650 08

1

1

--

Indicator/Multifunction Switch Ground

--

1

--

--

1. Headlamps Malfunction

2. Sidelight, Number Plate, and/or Tail Lamps Malfunction

Circuit/System Description

For headlamp operation, the body control module (BCM) monitors three signal circuits from the indicator/multifunction switch. When the indicator/multifunction switch is in the AUTO position, the three signal circuits are open and the BCM relies on the ambient light sensor input to turn the headlamps and daytime running lamps (DRL) ON and OFF. When the indicator/multifunction switch is placed in the OFF position, the indicator/multifunction switch headlamps OFF signal circuit is grounded, indicating to the BCM that the exterior lamps should be turned OFF. With the indicator/multifunction switch in the SIDELIGHTS position, the indicator/multifunction switch sidelights ON signal circuit is grounded, indicating that the sidelights have been requested. When the indicator/multifunction switch is in the HEADLAMP position, both the indicator/multifunction switch sidelights ON signal circuit and the indicator/multifunction switch headlamps ON signal circuit are grounded. The BCM responds by commanding the sidelights and headlamps ON.

Conditions for Running the DTC

Battery voltage must be between 9-16V.

Conditions for Setting the DTC

The BCM detects a short to ground in the indicator/multifunction switch main beam signal circuit.

Action Taken When the DTC Sets

The main beam headlamps will not operate.

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 vehicle ON/OFF switch cycles have occurred.

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 Testing

  1. Vehicle OFF, disconnect the harness connector at the S78 Indicator/Multifunction Switch.
  2. Vehicle OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 10 Ω between the ground circuit terminal 6 and ground.
  3. If greater then the specified range, test the ground circuit for an open/high resistance.
  4. Vehicle in Service Mode, verify the scan tool Main Beam Select Switch parameter is Inactive.
  5. If not the specified value, test the signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the K9 Body Control Module.
  6. Install a 3 A fused jumper wire between the signal circuit terminal 11 and ground. Verify the scan tool Main Beam Select Switch parameter is Active.
  7. 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 Body Control Module.
  8. If all circuits test normal, replace the S78 Indicator/Multifunction Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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


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