Power Liftgate System

POWER LIFTGATE
Anyone of the following will activate the power liftgate (PLG) system: remote keyless entry (RKE), overhead console switches, outside liftgate handle switch, or the DRBIII(R). These inputs are hard-wired to the Body Control Module (BCM) and can be monitored with a diagnostic tool. The BCM will send the message via PCI Bus to the Power Liftgate Mode (PLGM). The liftgate must be in the full open or full closed position to operate. Once the BCM sends a button activation message to the PLGM, the module shall read all inputs, outputs, and vehicle conditions to determine whether it shall open, close, or inhibit the PLG operation. Once the PLGM determines the vehicle conditions are safe for operation, the PLGM will initiate a chime for 2 seconds prior to the liftgate activation and 2 seconds during the open or close cycle.

During an opening or closing cycle, the PLG systems optical sensors, which are integrated into the drive unit, will detect the presence of obstacles. During an open cycle, multiple liftgate activation (RKE or overhead console switch) will reverse the liftgate to the full closed position. However, during a close cycle, a 2nd liftgate activation (RKE or overhead console switch) will reverse the liftgate to the full open position.

If the engine is cranked during a power open close, the PLG will pause, then resume after engine cranking. In addition, if the vehicle is placed in gear during an open cycle, the PLG shall reverse direction and begin closing. If the vehicle is placed in gear during a closing cycle, the PLG shall continue closing until fully closed. If the outside handle is activated during an open cycle, the PLG will become a full manual liftgate. If the outside handle is activated during a close cycle, the PLG shall reverse direction of travel to the full open position.

In the event of a complete power failure with the liftgate, it can be opened by removing the 25 mm plug at the lower trim of the liftgate near the latch and using a screwdriver, trip the latch. See Service Information for a detailed explanation. This will work for the non-power liftgate also.

DIAGNOSTIC FEATURES
The PLGM can be flashed on vehicle via PCI Bus with a DRBIII(R) diagnostic tool. The DRBIII(R) can read all inputs, actuate all outputs, read module information, and read diagnostic trouble codes. As a reminder, some DTC's can be set during normal PLG operation.

SYSTEM INHIBITORS
1. Battery voltage too high or too low (above 16V below 9.5V)
2. Vehicle in gear
3. Vehicle speed > 0 mph (0 km/h)
4. Outside temperature too high, above 179.6° F (82° C) or too low, below -22° F (-30 °C).
5. Liftgate locked will inhibit the interior switch from opening (overhead console). A locked liftgate can be power closed.
6. Pinch Sensor switch stuck shall inhibit the power close feature.

POWER SEAT SYSTEMS

POWER SEAT - DRIVER
The memory power seat provides the driver with 2 position settings for the drivers seat. Each power seat motor is connected to the MHSAPM/MSAPM with two motor drive circuits. Each circuit is switched between battery and ground. By being able to bi-directionally drive the circuits, the MHSAPM/MSAPM controls the movement iii the motors based on input from the power seat switch or from the position sensors when performing a memory recall. Each motor contains a potentiometer to monitor the seat position. To monitor the position of the motor, the MHSAPM/MSAPM sends out a 5-volt reference on the sensor supply circuit. The sensor is grounded back to the module on a common ground circuit. Based on the position of the sensor, the MHSAPM/MSAPM monitors the voltage change through the sensor on a separate signal circuit.

The MHSAPM/MSAPM stores the input value of each of the four seat potentiometers in memory when the system requests a set. The driver can initiate a memory recall, using either the door mounted memory switch or the RKE transmitter (if the remote linked to memory feature is enabled via the EVIC). When initiated the MHSAPM/MSAPM adjusts the four seat sensors (by using the motors) to match the memorized seat position data.

For safety, the memory seat recall is disabled by the MHSAPM/MSAPM when the vehicle is out of park position or if the speed is not zero. Any obstruction to seat movement over a 2-second delay will cause the seat to stop moving in which case a stalled motor would be detected by the MHSAPM/MSAPM and the corresponding seat output would be deactivated. However, if the object obstructing the seat is removed. the seat will function normally again.

POWER SEAT - PASSENGER
The passenger power seat is controlled by the MHSAPM/MSAPM through PCI BUS messages sent from the PDM. However, there are no memory features with the passenger seat.

MEMORY SYSTEM
The memory system consists of the drivers power seat, power mirrors, adjustable pedals. md radio presets. Refer to Memory Master under door Modules in this general information section for additional information.

The Memory Heated Seat Adjustable Pedal Module (MHSAPM) or the Memory Seat Adjustable Pedal Module (MSAPM) for vehicles equipped without heated seats are located under the driver's seat. It receives input from the following:
- driver's seat position sensors
- PCI Bus circuits
The MHSAPM/MSAPM uses these inputs to perform the following functions:
- position the driver's memory seat to the memory preset position
- position the pedals to the memory preset position
- send/receive memory system information over the PCI Bus.

The Memory Set Switch is wired to the Driver Door Module (DDM). After pressing the Memory Set Switch (#1 or #2), the DDM receives and interprets the analog signal and then sends a PCI Bus message to the MHSAPM/MSAPM to set or recall the memory seat position (1 or 2). The MHSAPM/MSAPM in turn sends a motion status message back to the DDM. If the message from the MHSAPM/MSAPM indicates no current motion, the DDM will send a recal message to the modules. In addition to setting seat position, the MHSAPM/ MSAPM will also set the adjustable pedals to the memory-preset position.

If any one of the memory-controlled systems is inoperative from its manual switch, use the schematics and diagnostic information to correct the concern. This manual addresses the memory problems only and it is assumed there is not a basic component failure.

MEMORY POWER MIRRORS
Each outside mirror contains vertical and horizontal bi-directional drive positioning motors and position sensors. The Driver Door Module (DDM) and Passenger Door Module (PDM) provide a 5-volt reference on the signal circuit to each position sensor. The sensors share a common ground circuit. The DDM and PDM monitor the position of the mirror motors by measuring the voltage on each signal circuit. then a memory position is set, the DDM and PDM monitor and store the position of the outside mirrors. The DDM and PDM adjust the mirrors to the appropriate positions when a memory recall message is received from the RKE or is requested from the memory recall switch.