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C1100 OBD-II Trouble Code: ABS Pump Switch Circuit Failure

check engine light

C1100 code definition

A C1100 trouble code means that the vehicle's Engine Control Unit (ECU) has registered an unspecified circuit failure in the Antilock Braking System's pump switch circuit.

What the C1100 code means

The antilock braking system offers the vehicle added traction. If the ABS pump isn't working properly, the ECU will run a diagnostic test to verify whether the parameters for a C1100 have been met. If a C1100 code has occurred and the pump switch circuit has failed, this will restrict use of the ABS system.

What causes the C1100 code?

A faulty ABS pump, sensor and/or control unit could explain the failed ABS circuit. Multiple ABS circuit failure are sometimes solved at once by replacing a single sensor. It may also be caused by a problem with the wiring and electrical connectors. Improper wiring or corroded, damaged and otherwise faulty 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 C1100 code?

The ABS system will be disabled or seriously hindered in the event of a C1100 code. In addition to the practical concerns, the C1100 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 C1100 code?

The C1100 code is first diagnosed by reading the code using an OBD-II scanner on the vehicle's ECU. Components (including the control unit, sensor and the pump itself) should be looked over to see if one of them is faulty. Any wiring and electrical connector related to the pump switch circuit should be looked over thoroughly for signs of damage, corrosion and disconnection. An additional diagnostic tool such as the Autohex scanner may help in pinpointing the source of the circuit failure.

Common mistakes when diagnosing the C1100 code

Chassis (or C-class) trouble codes may describe different issues depending on the make and model of vehicle in question. For instance, in the specific case of Mercedes vehicles, the C1100 code refers to a circuit fault in the left-front axle. Your OBD-II scanner may specify the code description for you. If you're not sure if you're interpreting the code correctly, refer to the vehicle's user manual, or contact the manufacturer.

How serious is the C1100 code?

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 C1101 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 C1100 code?

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 pump switch circuit, restart the vehicle. If the C1100 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, return to the diagnostic stage and see if there is anything you may have missed.

Additional comments for consideration regarding the C1100 code

Virtually all modern cars come equipped with ABS braking.

Need help with a C1100 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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