Component Description

Message Center

Component Description

Steering Wheel Switch - Message Center

The message center switch is the upper LH (Left Hand) steering wheel switch and is comprised of 5 buttons. The message center switch uses different resistance values associated with each specific button. The IPC (Instrument Panel Cluster) sends out a reference voltage to the upper LH (Left Hand) 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 IPC (Instrument Panel Cluster) which switch is pressed.

Low Washer Fluid Level Sensor

The low washer fluid level sensor is a reed type switch. The float assembly uses a magnet to close the contacts on the switch. The low washer fluid sensor is hardwired to the BCM (Body Control Module) through a single signal wire and is grounded to a body ground through a separate circuit. The BCM (Body Control Module) provides a battery reference voltage to the low washer fluid level sensor. When the washer fluid level is low, the float drops closing the switch and pulling the reference voltage low. When the washer fluid level is high, the float lifts off the switch and opens the circuit to the BCM (Body Control Module) sending the reference voltage high. The BCM (Body Control Module) monitors the washer fluid level and provides the washer fluid level low message to the IPC (Instrument Panel Cluster).

Compass Module

The compass module operates by monitoring the vehicle position relative to the earth's magnetic north. The magnetic fields generated by the earth's north and south poles are divided into zones that differ from each other with respect to how the magnetic fields appear. Most geographic areas (zones) have a magnetic north compass point that varies slightly from the northerly direction on maps. The compass module utilizes a voltage supply circuit, ground circuit and a communication circuit to provide the compass heading data for display.

Compass Accuracy

Factors within the vehicle can affect the ability of the compass module to accurately read the magnetic north. Calibrating the compass allows the compass module to compensate for these factors. Driving near power lines, or driving in the area of large iron or steel structures can temporarily change the compass heading. If the compass remains inaccurate after driving near such objects, calibrate the compass. REFER to Compass Calibration . Variations between zones is generally 4 degrees between adjacent zones and becomes noticeable as the vehicle crosses multiple zones. A correct zone setting eliminates the error. REFER to Compass Zone Adjustment .