B1899 – Microphone Input Signal Circuit Open

The ODBII code B1899 indicates that there is an open circuit in the microphone input signal circuit, which means the system is not receiving a proper signal from the microphone.

The severity of ODBII code B1899 is generally considered moderate.

Common Causes For: B1898 Chime Input #2 Circuit Short to Ground

• Damaged or frayed wiring
• Poor electrical connections
• Faulty microphone
• Defective audio control module
• Corroded connectors
• Short circuit in the circuit
• Open circuit in the wiring harness
• Faulty ground connection

Common misdiagnosis for B1899 Microphone Input Signal Circuit Open

• Faulty microphone
• Wiring issues
• Faulty audio control module
• Software glitches
• Poor ground connection
• Faulty connectors or terminals
• Issues with the vehicle’s infotainment system

Common Troubleshooting Steps

The OBD-II code B1899 indicates a problem with the microphone input signal circuit, specifically that the circuit is open. This can affect the vehicle’s hands-free communication system or other features that rely on the microphone. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other related trouble codes. This can provide more context about the issue.
• Inspect the Microphone:
• Locate the microphone in your vehicle (usually near the rearview mirror or in the overhead console).
• Check for physical damage or disconnection of the microphone.
• Examine Wiring and Connectors:
• Inspect the wiring harness connected to the microphone for any signs of damage, fraying, or corrosion.
• Ensure that all connectors are securely attached and free of dirt or moisture.
• Test the Microphone:
• If possible, test the microphone with a multimeter to ensure it is functioning correctly. Check for continuity and proper resistance.
• If the microphone is faulty, replace it.
• Check the Circuit:
• Use a multimeter to check for continuity in the microphone input signal circuit. Look for any breaks or shorts in the wiring.
• Verify that the circuit is receiving the correct voltage as specified in the vehicle’s service manual.
• Inspect the Audio System:
• If the vehicle has an aftermarket audio system, ensure that it is properly installed and compatible with the vehicle’s wiring.
• Check for any loose connections or improper wiring that could affect the microphone circuit.
• Clear the Codes: After performing the checks and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult the Service Manual: If the issue persists, refer to the vehicle’s service manual for specific diagnostic procedures related to the B1899 code and the microphone circuit.
• Seek Professional Help: If you are unable to resolve the issue, consider taking the vehicle to a qualified technician or dealership for further diagnosis and repair. By following these steps, you should be able to identify and resolve the issue related to the B1899 code.