GM Service Manual Online
For 1990-2009 cars only

Power Folding Top System Components

The power folding top system consists of the following components:

    • The folding top control (FTC) module
    • The pump, motor with thermistor and valve manifold
    • The hydraulic lines and the cylinders
    • The folding top mechanics
       - Top
       - Front panel
       - Rear panel
       - Deck lid
       - Latching mechanism for the top
    • Serial data communication
    • Position sensing sensors: Limit switches
       - Luggage/cargo cover
       - Folding top closed
       - Deck lid extended
       - Front latch latched and unlatched switches
    • Position sensing sensors: Potentiometers
       - The folding top
       - Front panel sensors
       - Rear panel sensors
    • Folding top open/close control switch
    • Power supply:
       - BATT MAIN 2 40A
       - Trunk Latch/Top SW 15A
       - A.C Latch/PK BRK B 10A
       - Tilt/Tele Sw/Mem Seat Mod/Top Sw 10A
    • Ground G301: to the FTC module and the pump and valve assembly
    • Ground G202: for the auxiliary power relay and the valet switch

System Description

The folding top control (FTC) module has 2 modes of operation, the folding top control and the deck lid control. The folding top is activated by the folding top control switch. The deck lid is activated with the interior trunk release switch, key FOB, external key and the trunk close switch.

Through input information, the FTC module performs the following tasks:

    • Determines the state of all the moving components of the folding top system at any time during and open or close operation
    • Makes corrections in the positions of the components when necessary
    • Continues in the direction indicated by the FTC switch

The FTC module can stop and reverse the operation at any point when you apply the folding top control switch. To avoid an inadvertent operation of the folding top system when fully open or closed, a 0.75 second delay occurs after the use of the control switch before the FTC module starts the operating sequence. When you activate the system from a suspended state, the response time is less.

System Operation

Before any movement of the top is allowed, the folding top control (FTC) must be aware of the following conditions:

    • The windows must be normalized. Refer to Power Window Reinitialization.
    • The ignition must be placed in ACCESSORY or RUN, power mode in RUN.
    • The transmission must be placed in PARK.
    • The valet switch must be inactive.
    • The pump motor temperature must be within operating range.

The sequence for opening the top is as follows:

  1. Hold the open/close control switch to the open request position.
  2. The folding top status changes to Opening.

  3. A message is sent to disable the windows from operating using the door switches.
  4. The windows open using the Express open mode.
  5. The deck lid is unlatched.
  6. The deck lid opens, the front panel opens and the front latch unlatches.
  7. The top retracts to the open position and is stowed in the rear compartment.
  8. The rear panel is extended.
  9. The front latch latches securing the top and the front panel closes.
  10. The deck lid closes.
  11. The deck lid latches.
  12. The top status changes from Closed to Open and a chime tone is heard.
  13. The windows are enabled.

The sequence for closing the top is as follows:

  1. Hold the open/close control switch in the close request position.
  2. The folding top status changes to Closing.

  3. A message is sent to disable the windows from operating using the door switches.
  4. The windows open using the Express open mode.
  5. The deck lid is unlatched.
  6. The deck lid opens, the front panel opens and the front latch unlatches.
  7. The rear panel retracts.
  8. The top extends to the closed position.
  9. The rear panel remains retracted.
  10. The front latch latches and the front panel closes.
  11. The deck lid closes.
  12. The deck lid latches.
  13. The top status changes from Open to Closed and a chime tone is heard.
  14. The windows are enabled.
  15. Raise the windows using the Express up mode, by releasing and pressing the open/close control switch within 5 seconds of the top being secured in the closed position.

Potentiometer Sensors

The folding top control (FTC) module determines the state of all the moving components of the folding top system during an open or close operation using the potentiometers that monitor the folding top and the front and rear panels. The FTC module records the open and close reference positions and determines the current position of the panel, shown as counts on the scan tool. For example, if a sensor open reference is set at 100 counts and the close reference is set at 200 counts, the component will operate within those limits. As a component reaches the reference point, the system will continue to drive the component to secure the component in place. This means that the status of the component will be outside of the reference position counts.

If a component does not reach a learned reference position, based on counts, the system will continue to drive that component until the component reaches the reference point. If this reference position is not achieved, the system will time-out and will not complete the cycle.

When an inspection of the components or a repair to the system is completed, perform a folding top learn procedure. Refer to Power Folding Top Learn.

Hydraulic Control

The folding top control (FTC) module will control the hydraulic system, which moves the folding top components, by controlling the On/Off state and the direction of the hydraulic pump motor, and by controlling the open/close state of each valve. The 5 valves controlled by the FTC module move the following components:

    • The folding top
    • The front panel
    • The front latch
    • The deck lid

The rear panel is controlled by the pump bypass valve located at the hydraulic reservoir. The direction of the panel movement is based on the motor direction.

Whenever the open/close control switch is released or the top becomes inoperative in a suspended state, pressure will be maintained in the system to avoid drifting and damage of components. After 4 minutes the hydraulic pressure will be released by cycling the valves ON and OFF. This allows the top to gradually settle to a resting position.

Pump Motor

The pump motor continuously monitors the thermistor temperature sensor for temperatures which are too high or too low. Different operating temperature settings are required for the deck lid and the folding top functions. If the control module detects a temperature between the pump motor pre-alarm setting and the pump motor alarm setting, the current open/close operation shall be completed, but no new top operation will be allowed until the pump motor cools below the pre-alarm setting. If the temperature reaches the pump motor alarm value, all top operation will cease. A low temperature value is sent over the class 2 serial data that will also cease all operation when the outside temperature is below this value. The pump motor temperature settings are:

    • Too high pre-alarm of 105°C (221°F)
    • Too high alarm of 115°C (239°F)
    • Too cold for folding top operation of -20°C (-4°F)
    • Too cold for deck lid operation of -30°C (-22°F)

Driver Notification

Under certain conditions the driver shall be alerted with one of several messages. These messages are sent through class 2 serial data to the driver information center/instrument panel.

    • CLOSE CARGO DIVIDER: If the compartment partition barrier is not in place and top operation is attempted
    • TOP INOP OUT OF PARK: If the power mode is in RUN, but the transmission is not in PARK and a top operation is attempted
    • TOP MOTOR OVER TEMP: If the motor thermistor temperature is above the operating range
    • TOP NOT SECURE: If the top open/close switch is released before an open or close operation is complete
    • TOP TOO COLD TO MOVE: If the motor thermistor temperature is below the operating range
    • TRUNK AJAR: If the deck lid operation is not completed
    • TOP INOP-VALET ON: When the valet switch is switch ON active, any request to operate the top or deck lid will be inhibited.

Default Operation

If the folding top control (FTC) module is requested to operate the folding top and discovers that a component is not in the correct position based on information from other inputs, the FTC will move those components to a safe position before executing the sequence requested by the control switch. At first this will look as though the folding top is moving in the incorrect direction, but as soon as the FTC module moves those components to a safe position, the FTC will then operate the system as requested.