B1567

What Does Code B1567 Mean?

DTC B1567 signifies a detected fault within the high-beam headlamp circuit. The Body Control Module (BCM), or in some vehicle architectures, a Generic Electronic Module (GEM) or Smart Junction Box (SJB), is responsible for monitoring the electrical integrity and operational status of the vehicle’s exterior lighting systems, including the high-beam headlamps. When the BCM detects an electrical anomaly within the high-beam circuit, such as an open circuit (no current flow due to a break), a short to ground (excessive current flow bypassing the load), or a short to voltage (unintended power supply), it registers a B1567 code. This indicates that the module’s commanded output for high-beam illumination is not being achieved or an unexpected electrical state is present, thereby impairing the high-beam function.

Common Symptoms

• High-beam headlamps fail to illuminate when activated.
• Only one of the high-beam headlamps illuminates (indicating a circuit fault specific to one side, if circuits are separated).
• The high-beam indicator lamp on the instrument cluster does not illuminate or flickers erratically when high beams are commanded.
• Dim or intermittent operation of the high-beam headlamps.
• Headlamps may be stuck on low-beam, regardless of the multi-function switch position.
• Visible signs of a burnt-out bulb filament or damaged wiring in the headlamp assembly.

What Causes the Code B1567?

• Faulty High-Beam Headlamp Bulb(s): A common cause, where a burnt-out filament creates an open circuit, preventing current flow.
• Wiring Harness Issues: Damage to the high-beam circuit wiring, including open circuits (broken wires), short to ground (chafed insulation exposing the wire to chassis ground), or short to voltage (wire touching an unintended power source).
• Corroded or Loose Electrical Connections: Poor electrical contact at the headlamp bulb sockets, intermediate wiring harness connectors, or at the BCM itself, leading to high resistance or intermittent open circuits.
• Faulty High-Beam Switch (Multi-Function Stalk): An internal failure of the multi-function switch, which controls the high-beam function, preventing the BCM from receiving the correct input signal or properly routing power.
• Defective High-Beam Relay: If the circuit utilizes a dedicated high-beam relay, it could be stuck open, stuck closed, or exhibit high internal resistance, disrupting power flow to the headlamps.
• Internal Body Control Module (BCM) Failure: Less common, but a defective driver circuit or other internal component within the BCM responsible for controlling the high-beam output can fail.

How to Diagnose and Troubleshoot

Diagnosis of B1567 requires a methodical approach, utilizing a digital multimeter (DMM) and an OBD-II scanner capable of accessing BCM codes.

1. Initial Visual Inspection: Begin by visually inspecting both high-beam headlamp bulbs for any signs of a burnt-out filament. Carefully check the wiring harness leading to the headlamp assemblies, focusing on areas prone to heat, chafing, or moisture. Inspect bulb sockets and connectors for corrosion, damage, or loose terminals.
2. Retrieve DTCs and Freeze Frame Data: Connect an OBD-II scanner capable of reading BCM/chassis codes. Confirm the presence of B1567 and note any accompanying codes. Analyze freeze frame data if available, as it can provide insights into operating conditions when the fault was set. Clear the DTCs after recording.
3. Verify High-Beam Operation: With the ignition ON (and engine running if necessary for system activation), activate the high-beam function via the multi-function switch. Observe both headlamps and the high-beam indicator on the instrument cluster.
4. Power and Ground Test at Bulb Socket:
   • Disconnect the high-beam bulb(s).
   • Using a DMM set to DC Volts, back-probe the power terminal of the bulb socket. Connect the other DMM lead to a known good chassis ground.
   • Activate the high beams. You should measure approximately battery voltage (12V-14V). A lack of voltage or significantly low voltage indicates a power supply issue upstream.
   • Test the ground circuit by connecting the DMM to the ground terminal of the bulb socket and a known good power source (e.g., battery positive terminal). You should measure battery voltage. Alternatively, measure resistance between the ground terminal and chassis ground; it should be less than 0.5 ohms.
5. Circuit Resistance and Continuity Test:
   • For safety, disconnect the negative battery terminal.
   • Consult the vehicle’s wiring diagram to identify the high-beam power circuit from the BCM to the headlamp. Disconnect the appropriate harness connector from the BCM.
   • Using a DMM set to Ohms, measure the resistance of the high-beam power wire from the BCM connector pin to the respective bulb socket’s power terminal. Resistance should be very low (typically less than 0.5 ohms). High resistance indicates corrosion or a damaged wire.
   • Check for shorts to ground: Measure resistance between the high-beam power wire and chassis ground. The reading should be infinite (OL or open loop). A low resistance indicates a short to ground.
   • Check for shorts to voltage: Visually inspect for damaged insulation where the wire could contact a constant power source. This is best done by visual inspection.
6. High-Beam Switch and Relay Testing:
   • Refer to the wiring diagram to locate the multi-function switch terminals and any high-beam relays.
   • For the switch: Using the DMM, check for proper voltage changes or continuity at the switch’s output terminals to the BCM when the high beams are activated.
   • For relays: If a relay is present, perform a functional test by checking its coil resistance, applying 12V to the coil terminals to listen for an audible click, and checking continuity across its power contacts. Replace if faulty.
7. BCM Output Verification: If all external wiring, bulbs, switches, and relays test good, the fault may lie within the BCM itself. This often requires a factory-level scan tool or equivalent to monitor BCM output commands and actual voltage/current readings for the high-beam circuit. If the BCM commands high beams but no output is present at its connector, the BCM is likely at fault.

Recommended Repairs and Solutions

• Replace Faulty Headlamp Bulb(s): If a burnt-out bulb is identified, replace it with a new bulb of the correct wattage and type, ensuring proper seating in the socket.
• Repair or Replace Damaged Wiring: If an open circuit, short to ground, or short to voltage is found in the wiring harness, repair the damaged section using appropriate gauge wire, solder and heat shrink, or specialized crimp connectors. If damage is extensive, replace the entire affected harness segment.
• Clean and Secure Electrical Connectors: Address any corrosion in bulb sockets or harness connectors using an electrical contact cleaner and a small brush. Apply dielectric grease to prevent future corrosion. Ensure all connections are fully seated and terminals are tight.
• Replace the High-Beam Switch: If diagnostic steps indicate a faulty multi-function switch (stalk), replace it according to manufacturer specifications. This typically involves removing trim panels around the steering column.
• Replace the High-Beam Relay: If a faulty relay is identified, replace it with a new, OEM-specified relay. Ensure the new relay is properly seated in its socket.
• Replace the Body Control Module (BCM): If all other components and wiring have been thoroughly tested and confirmed good, and the BCM is determined to be at fault, replacement may be necessary. It is crucial to note that BCM replacement almost always requires specialized programming (e.g., VIN programming, key initialization, module configuration) using a factory-level scan tool or equivalent. This procedure typically requires services from a dealership or an independent automotive shop equipped with the necessary diagnostic and programming tools.
• Post-Repair Verification: After completing any repair, clear the DTCs from the BCM using an OBD-II scanner. Thoroughly test the high-beam functionality multiple times to ensure the repair is successful and the B1567 code does not return.