Principles of Operation (How Does It Work?)
Principles of Operation (How Does It Work?)Power Window Control
The driver power window is controlled by the front electronics module (FEM). The driver power window regulator control switch and motor are hardwired directly to the FEM. The FEM will read the window regulator control switch actuation and provide the corresponding output to the window motor. If one-touch operation is selected, the FEM powers the driver window motor for seven seconds or until the FEM senses the motor is stalled. If the window track, regulator or glass weatherstrips cause the glass to bind, the FEM may interpret this as a motor stalled condition and halt motor operation.
The passenger and rear quarter flip window motors are hardwired directly to the window regulator control switches and are not controlled by the FEM.
Heated Rear Glass
The heated rear window is controlled by the powertrain control module (PCM), front electronic module (FEM) and instrument cluster. The ignition switch must be in RUN and the engine above 400 rpm for the heated rear window to operate. The heated rear window operates as follows.
Pressing the heated rear window switching (which is hardwired to the instrument cluster) supplies a ground signal to the instrument cluster. Upon receiving the ground input from the heated rear window switch, the instrument cluster:
- sends a command ON signal to the FEM over the J1850 network.
- supplies a power source to the heated rear window ON indicator in the climate control assembly. This output circuit is also hardwired.
Upon receiving the command ON signal from the instrument cluster, the FEM will
- check if the rpm message sent by the PCM is above 400 rpm.
- If the rpm is above 400, the FEM will enable the heated rear window relay by supplying a ground to the relay coil. This closes the relay contacts and supplies power to the rear window grid.
- In the event an rpm or ignition switch invalid or missing data message is present, the FEM will not enable the heated rear window relay.
The heated rear window is a configurable feature for the FEM. For this feature to operate it must have been configured ON when the vehicle was built.
Delayed Accessory
Delayed accessory operation allows the power windows and radio to operate for up to 10 minutes after the ignition is turned to OFF. The delayed accessory function is controlled by the FEM. When the ignition switch is turned from RUN to OFF, the FEM will begin the timing sequence. If a door is opened or the ignition switch is activated to another position, the FEM will cancel the delayed accessory operation.