Power Windows
Power Windows
The power window operation on the E46 is similar to previous systems. Features of the system include:
- Control of the front and rear door window motors is carried out directly by the GM.
- One-touch operation in both directions on all four windows.
- Cable type window regulator used for all windows.
- Anti-trap detection is provided by the pressure sensitive finger guard (same as E38/E39).
- A new style window switch is being introduced with the E46. The switch is pulled up to raise the windows and pushed down to lower them.
- The rear window switches located in the rear doors can be deactivated by the pressing child lock out switch in the center console.
- Convenience closing/opening of the windows from the driver's lock cylinder or convenience opening only from the FZV remote key (FZV operation can be owner customized with the Car Memory Function).
- Window operation with the ignition switched off until a door is opened or 16 minutes has elapsed after the key is switched off.
- Window load switching is through relays integral of the GM. The GM V monitors the current draw for end limit position. The maximum run time for the window motors is limited to 8 seconds. This allows the motors to be switched oft if the end limit load sensing fails.
Components
New Style Window Switches
The E46 power window switch design is a new push - pull type switch. Each switch provides the GM V with the familiar coded ground signaling strategy as previous two wire switches.
Pushing a switch to the first detent and holding provides a single ground signal on one wire requesting the GM to operate the window motor in the down direction. When released, the ground signal is removed and the window motor stops.
Momentarily pushing the switch to the second detent and releasing provides an additional ground signal on the second wire requesting the "one touch mode", operating the window motor automatically. The motor runs the window down until it reaches it's end stop.
The switch functions in the same manner for the upward run of the window motor but the ground signal sequencing is reversed.
Each rear door has a single window switch located in the door handle trim.
Rear Window Child Lockout Switch
The rear window child lockout switch is incorporated in the driver's side window switch block. It provides a constant ground signal to the GM preventing the windows from being operated from the rear door switches.
The lockout switch ground signal is overridden by the GM if the MRS II crash signal is activated.
Service Note:
Switch block removal from the console has changed on the E46.
The console trim must be removed from the console base. The switch blocks can be removed by pushing the lock tabs and dropping the switch from the trim.
Power Window Motors
The window motors are mounted on the cable regulators (E38/E39). The window motor control circuit consists of two wires for operating the motor in both directions.
The motors are activated by relays in the GM. The relays provide either power or ground depending on the direction of window travel.
The GM controls the polarity of the based on a request to run the window (window switch, Convenience Opening/Closing).
The windows are run to their limit stops which is detected by an amperage increase in the control circuit. Additionally, the window run cycle is limited to an 8 second duration if in case the amperage increase is not detected or there is a malfunction with the regulator.
Window Motor Limit Stop Function
If the windows are run up and down continuously a limit stop function is activated to prevent the window motors from overheating. The GM monitors the number of times the window motors are activated. It counts each cycle and stores the number in memory.
If the repetitive window activation (up/down) exceeds one minute, the GM deactivates the internal relays and disregards any further input requests. The GM provides motor activation after a short duration but not for the full one minute monitoring cycle.
Over time, the GM slowly reverses the stored count of activation until the stored number equals 0.
Window Anti-Trap Detection
The window anti-trap detection feature is only active in the one touch and convenience close modes of operation. If the window switch is pushed/pulled and held, the Anti-trap feature will not function.
The rubber pressure guard located at the top edge of each door frame consists of two contact strips that close when subjected to pressure. This provides anti-trap detection and signal generation to the GM V.
When the contact strip closes, the window immediately (10 ms) reverses direction as with previous anti-trap systems. The contact strip does not require that the anti-trap feature be initialized prior to operation.
The E46 pressure sensor finger guard has a resistance of 3.0 KOhm and it is monitored for open circuit. When pressed, the monitored resistance changes to < 1 KOhm. Faults with the anti-trap system require that the window switch be held to close the window.
Convenience Opening/Closing
As with previous ZKE systems, the GM V provides the convenience open/close feature providing control of the power windows (and sunroof) from outside the vehicle with the key in the driver's door lock. The FZV provides the same function for the opening only.
- The anti-trap feature is active during convenience closing from the driver's door lock.
- The convenience open feature provides outside activation of the windows and sunroof in the same manner.
- If the GM receives a request to operate convenience close or open for more than 110 seconds, the function is deactivated and a fault code is stored.
- The Car Memory Feature can activate and deactivate the Convenience Open Feature from the FZV's control.