Component Description

WARNING: This page is about a different car, the 2015 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Brake Fluid Level Switch

The brake fluid level switch is mounted in the master cylinder reservoir and is hardwired to the BCM through a signal circuit and grounded through a separate body ground circuit. The BCM provides a reference voltage to the brake fluid level switch. When the brake fluid level is low, the float drops, allowing the switch to close, pulling the reference voltage low. When the brake fluid level is high, the float lifts, opening the switch contacts, sending the reference voltage high on the signal circuit to the BCM.

The brake fluid level switch uses an internal resistor in parallel. This enables the BCM to differentiate between a disconnected brake fluid level switch connector and a full level condition.

Oil Pressure Switch (3.5L Engine)

The oil pressure switch is a normally open switch that is hardwired to the PCM through a single signal circuit. The ground is provided by the switch housing when it is mounted on the engine. The PCM provides a reference voltage to the oil pressure switch. When oil pressure is low, the oil pressure switch remains open, sending the reference voltage high. When the oil pressure is sufficient, the oil pressure switch closes, pulling the reference voltage low to the PCM.

Oil Pressure Switch (2.7L And 5.0L Engine)

The oil pressure sensor is hardwired to the PCM through voltage reference (VREF), signal and return circuits. The PCM provides the sensor voltage supply on the VREF circuit and monitors the change in voltage though the signal and return circuits as the oil pressure changes.

Steering Wheel Switch - Message Center

The message center switch is part of the LH steering wheel switch and is comprised of 5 buttons (up, down, left, right and OK). The message center switch uses different resistance values associated with each specific button. The SCCM sends out a reference voltage to the upper LH steering wheel switch on the input circuit and monitors the voltage drops. The voltage drop varies depending upon the resistance of the specific button pressed, providing indication to the SCCM which button is pressed.