DTC Code C1090 – What does this code mean?

<ul> <li><b>Anti-Lock Brake System (ABS) Warning Light ON</b>: The ABS warning light illuminates on the dashboard, indicating a potential issue with the ABS brake lamp control circuit. This can be caused by a faulty ABS control module, damaged wiring, or a malfunctioning brake lamp switch.</li> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The engine light or service engine soon warning light may also turn on, suggesting a broader issue that could be related to the ABS system. Potential causes include a low voltage condition in the ABS brake lamp control circuit, a defective ABS relay, or a problem with the vehicle's electrical system.</li> </ul>

<ul><li>The ABS brake lamp itself may be faulty, leading to improper functioning of the brake lamp control circuit.</li><li>An open or shorted harness in the ABS brake lamp can disrupt the electrical flow, causing the control circuit to register a low signal.</li><li>Poor electrical connections within the ABS brake lamp circuit can result in intermittent or weak signals, triggering the error code.</li></ul>

<ul> <li><b>Initial Inspection</b>: Check the ABS brake lamp for any visible damage or disconnection. Ensure the lamp is properly seated and the bulb is functional.</li> <li><b>Check ABS Fuse</b>: Inspect the ABS fuse in the fuse box. Replace if blown.</li> <li><b>Inspect Wiring and Connectors</b>: Examine the wiring and connectors leading to the ABS brake lamp for any signs of wear, corrosion, or disconnection. Repair or replace as necessary.</li> <li><b>Test Voltage at ABS Lamp</b>: Using a multimeter, measure the voltage at the ABS brake lamp connector. Ensure it matches the manufacturer's specifications.</li> <li><b>Check ABS Control Module</b>: Verify the ABS control module is functioning correctly. Use a scan tool to check for any additional codes or faults.</li> <li><b>Perform Continuity Test</b>: Conduct a continuity test on the ABS brake lamp circuit to ensure there are no breaks or shorts in the wiring.</li> <li><b>Inspect Ground Connections</b>: Ensure all ground connections related to the ABS system are secure and free of corrosion.</li> <li><b>Re-test System</b>: After performing the necessary repairs, clear the DTC code and re-test the ABS system to confirm the issue is resolved.</li></ul>

<p>The DTC code C1090 indicates a low voltage issue in the ABS Brake Lamp Control Circuit. This is a <b>critical</b> issue as it affects the Anti-lock Braking System (ABS), which is essential for safe braking performance.</p><ul><li>Immediate action is required to diagnose and repair the circuit to ensure proper ABS functionality.</li><li>Failure to address this issue can lead to compromised braking efficiency and increased risk of accidents.</li></ul>