Code C1220 on the 2020 Chrysler Pacifica indicates a fault in the left front brake pad wear sensor circuit. This sensor provides advance warning that brake pads are wearing thin and need replacement, allowing scheduled maintenance before the pads wear to a dangerous level.
Brake Pad Wear Sensor Design
The wear sensor is a simple circuit embedded in or attached to the brake pad. As the pad wears down, eventually the metal contact portion of the sensor touches the rotor, completing a circuit (or breaking it, depending on design). The Pacifica's system monitors this circuit and alerts the driver when wear reaches a specified threshold or when the circuit fails.
Symptoms and Warnings
With C1220 present, a brake pad wear warning or brake service message appears on the instrument cluster. This may occur even if the pads still have material remaining - indicating a sensor or circuit fault rather than actual wear. Inspect the pads visually to determine whether the warning reflects reality or an electrical problem.
Diagnostic Process
First, visually inspect the left front brake pads. If they appear adequately thick, the sensor or its wiring has failed. The sensor wire runs from the brake pad through the caliper area and connects to the vehicle harness near the wheel well. Road debris and heat damage are common causes of wire failure. The sensor itself may break during normal brake service if not removed carefully.
Repair Procedure
If pads are worn, replace them along with new wear sensors. If the sensor has failed prematurely, replace the sensor and inspect wiring. Wear sensors are typically inexpensive parts but require wheel and possibly caliper removal for access. After installation, clear codes and verify the warning extinguishes.