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C1103 OBD-II Trouble Code: ABS Hydraulic Brake Switch Circuit Failure

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C1103 code definition

A C1103 trouble code indicates that the vehicle's Engine Control Unit (ECU) has detected an unspecified failure in the hydraulic brake switch circuit of the Antilock Braking System (ABS).

What the C1103 code means

The ABS helps to minimize the risk of wheel slippage and loss of steering control. If the hydraulic brake switch circuit has experienced a failure, this may result in the failure or severe limitation of the ABS system. Although regular braking should function normally, this will have a significant impact on the vehicle's sense of handling.

What causes the C1103 code?

If your vehicle is suffering from a C1103 code, a faulty switch, sensor or ABS control unit may be to blame. issues with wiring are a likely cause. Corroded, damaged, faulty and otherwise poorly installed circuitry may be to blame for this circuit failure. In some rare cases, the ECU itself may be faulty, mistakenly reporting the trouble code as a result. Due to the rareness of this cause, it should only be considered once all other plausible causes have been exhausted.

What are the symptoms of the C1103 code?

A C1103 trouble code may result in a malfunctioning or disabled ABS brake system. Regular braking should function properly, unless more brake-related codes have been stored. In addition to the practical concerns, the C1103 code will be accompanied by an illuminated check engine light on the vehicle's dashboard, as well as a stored trouble code in the ECU that can be read using an OBD-II scanner. These symptoms are present in a purely diagnostic context, and may be disregarded once the specific issue has been identified.

How does a mechanic diagnose the C1103 code?

A mechanic may first diagnose the C1103 code by reading the ECU using an OBD-II code reader. The ABS control unit, sensors and switch itself should be analyzed for telling signs of faultiness. Any electrical wiring and connectors should looked over for signs of disconnection, corrosion improper wiring/installation, damage and faultiness. Using a tool such as an Autohex scanner can make it easier to locate the source of the circuit failure.

Common mistakes when diagnosing the C1103 code

Chassis (or C-class) trouble codes may describe different issues depending on the make and model of vehicle in question. In Mercedes vehicles, for example, a C1103 trouble code refers to a circuit issue with the car's right-rear axle. Your OBD-II scanner may specify the code description for you. If you're not sure if you're interpreting the code correctly, contact the vehicle's manufacturer or a YourMechanic representative for help.

How serious is the C1103 code?

A malfunctioning antilock braking system increases the margin of danger driving the vehicle. Your vehicle will handle differently than usual without its proper ABS traction. Although the vehicle may still technically be drivable without the Antilock Braking System, it significantly increases the risk of accidents. A C1103 trouble code is considerably more serious if the vehicle is typically driven on less-than-optimal driving conditions and routes.

What repairs can fix the C1103 code?

If a switch, sensor or ABS control unit have been found out as faulty, they'll need to be replaced. Any electrical wiring and connectors that have been identified as broken, damaged or faulty should be replaced, repaired or rewired accordingly. In the rare event that the ECU has been identified as faulty, it will need to be reprogrammed or replaced altogether. Once you've made any necessary repairs to fix the ABS hydraulic brake switch circuit, restart the vehicle. If the C1103 hasn't been properly solved yet, this will give the trouble code a chance to recur. In the event that the issue hasn't been solved, inspect the circuit again for potential causes you may have overlooked the first time around.

Additional comments for consideration regarding the C1103 code

Model-specific C1103 code descriptions include a VSS circuit failure in the right-rear axle (for Mercedes vehicles), and a front right sensor ABS sensor issue for many Nissan models.

Need help with a C1103 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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