C1100 Code: Meaning, Causes, and Symptoms | OBD2 Codes

C1100 – ABS Pump Switch Circuit Failure


C1100 Possible Symptoms


Anti-Lock Brake System (ABS) Warning Light ON,Engine Light ON (or Service Engine Soon Warning Light)


C1100 Possible Causes


ABS Pump Switch / Wiring intermittently open/shorted,Faulty / intermittent connection at the Anti-Lock Brake Control Module (ABCM or EBCM),Faulty Anti-Lock Brake Control Module


C1100 Description


When the driver stops too fast, and one or more wheels begin to lock up, the ABS system takes over. It sees the wheel or wheels slowing down too rapidly by way of wheel speed sensors. When this happens, it shuts off brake fluid to the wheel with the inlet valve/coil, and releases the pressure with an outlet valve/coil. The ABS pump is what replenishes the brake fluid, and the ABS Pump Switch informs the ABS control module when the pump is running/turns on the pump depending upon manufacturer??? application. The ABS pump switch is typically found on vehicles with 4 Wheel Anti-Lock Brakes. The ABS system checks to be sure that the switch electrical circuit is ok every time the key is turned on and the ABS module is powered up. If there is a problem with the wiring to the switch or the switch itself, the ABS module will communicate over a data bus to the instrument cluster to turn on the amber Anti-Lock Light and the Red Brake Warning Light, and ABS will be disabled. In this case, the module has checked the ABS pump switch wiring and found the circuit has an electrical problem. This sets a C1100 in memory.