Convertible Top: Description and Operation
HOOD OPERATING SYSTEM TSAS
The TSAS (Top Stack Actuation System) hood operating system raises and lowers the hood when the relevant circuit is closed by means of the "ROOF" switch.
In addition to the six electric motors, the TSAS consists of a control module, three potentiometers and seven microswitches. Highly simplified, the system works by means of electric motors which are activated by the control module, causing the hood to be raised or lowered. The control module also checks by means of potentiometers that all movements take place in the right order. When hood movement comes to an end, microswitches confirm that the hood is latched at front and rear and that the tonneau cover is latched to the body.
Should any fault arise, hood movement will be interrupted and a signal sent to the SID which will then sound a buzzer and display an error message.
The hood operating system consists of the following components:
1 Control module
2 Main motors (2)
3 Fifth bow motors (2)
4 Tonneau cover motor
5 Fifth bow latch motor
6 Main hood-movement potentiometer
7 Fifth bow movement potentiometer
8 Tonneau cover movement potentiometer
9 Microswitches in windscreen frame latch fittings (2)
10 Fifth bow latch microswitch
11 Tonneau cover latch microswitches (2)
12 Hood stowage bag microswitches (2)
13 Tonneau cover access flap cables
14 "ROOF" switch
15 Emergency hood-opening handle
16 SID
17 Boot lid release button
18 Boot lid switch
19 Boot lid lock motor
20 Window lift switches
21 Speed signal from right-hand rear wheel, via ABS control module
Control Module
The control module is mounted in the boot on the left-hand side. By means of potentiometers and microswitches it controls the electric motors which raise and lower the hood and tonneau cover. At the same time it performs a self-test to detect any faults in the system.
The self-test includes an internal control module test and a plausibility check of the potentiometer and microswitch signals. The six electric motors are checked every time they are used. Any faults detected by the control module are stored in its memory as diagnostic trouble codes. The control module can store up to five diagnostic trouble codes simultaneously. Diagnostic trouble codes must be cleared using an ISAT scan tool.
In order to maintain the best possible electrical contact in the potentiometer, microswitch and "ROOF" button connectors, the control module applies a 12v 100 mA current to the contact surfaces so that any impurities on them will be burnt off. This is done for 500 ms before the control module's microprocessor assumes the idle state.
The control module has three connectors: a 42-pin connector designated K42 and two 20-pin connectors designated K20 (black) and K2OW (white). The functions covered by the different connectors are shown in the control unit pinout values. Pinout Values and Diagnostic Parameters
To distinguish between the pin numbers of the different connectors, all pin numbers are specified together with the designation of the relevant control module connector.
Control Module Inputs
1 Voltage from +30 circuit, pin 20 (K20), BOB No.62
2 Voltage from +15 circuit, pin 9 (K20), BOB No.51
3 Power ground, pin 10 (K20), BOB no.52
4 Signal ground, pin 18 (K42), BOB No.18
5 Potentiometers
- Main motor, pin 30 (K42), BOB No.30
- Fifth bow, pin 31 (K42), BOB No.31
- Tonneau cover, pin 32 (K42), BOB No.32
6 Microswitches
- Header latch, hood, left-hand, pin 24 (K42), BOB No.24
- Header latch, hood, right-hand, pin 38 (K42), BOB No.38
- Fifth bow, pin 25 (K42), BOB No.25
- Tonneau cover, left-hand, pin 26 (K42), BOB No.26
- Tonneau cover, right-hand, pin 40 (K42), BOB No.40
- Hood stowage bag, left-hand, pin 27 (K42), BOB No.27
- Hood stowage bag, right-hand, pin 41 (K42); BOB No.41
7 Switches
- Hood operation, pins 28 and 42 (K42), BOB Nos. 28 and 42
- Boot lid, pin 7 (K42), BOB No.7
- Boot lid lock, pin 19 (K20), BOB No.61
- All windows up/down, pins 1 and 2 (K2OW), BOB Nos. 63 and 64
- Door window, left-hand, pins 17 and 20 (K2OW), BOB Nos. 79 and 82
- Door window, right-hand, pins 1 and 2 (K42), BOB Nos. 1 and 2
- Rear quarter light, left-hand, pins 3 and 4 (K42), BOB Nos. 3 and 4
- Rear quarter light, right-hand, pins 5 and 6 (K42), BOB Nos. 5 and 6
8 Speed, from ABS control module, pin 12 (K42), BOB No.12
9 Diagnostics communication from ISAT Scan Tool, pin 10 (K42), BOB No.10
Control Module Outputs
1 Motors
- Main motor pins 1 and 11 (K20), BOB Nos. 43 and 53
- Fifth bow, pins 13 and 14 (K20), BOB Nos. 55 and 56
- Fifth bow latch, pins 2 and 12 (K20), BOB No.44 and 54
- Tonneau cover, pins 16 and 17 (k20), BOB Nos. 58 and 59
- Boot lock, pin 18 (K20), BOB No.60 2 Motors, window lifts
- Door window, left-hand, pins 18 and 19 (K2OW), BOB Nos. 80 and 81
- Door window, right-hand, pins 13 and 14 (K20W), BOB Nos. 75 and 76
- Rear quarter light, left-hand, pins 11 and 12 (K2OW), BOB Nos. 73 and 74
- Rear quarter light, right-hand, pins 15 and 16 (K2OW), BOB Nos. 77 and 78
3 Power supply
- Potentiometers, pin 15.(K42), BOB No.15
- Microswitch, unactuated; pin 22 (K42), BOB No. 22
- Microswitch, actuated, pin 23 (K42), BOB No.23
4 Ground, potentiometers, pin 20 (k42), BOB No.29
5 Communication with SID, pin 11 (k42), BOB No.11
6 Diagnostics communication with ISAT Scan Tool, pin 10 (K42) BOB No.10
Idle State
If the control module microprocessor is inactive for more than three seconds it will assume the idle state. The control module then turns off the microprocessor to reduce the risk of EMI (Electromagnetic Interference), chiefly where radio reception is concerned.
No self-test is carried out in the idle state. Any faults that occur will be detected when the microprocessor becomes active again.
The microprocessor leaves the idle state as follows:
- When the ignition switch is turned to ON.
- When the "ROOF" switch for operating the hood is activated.
- When any of the five switches in the control console is used to operate one or all window lifts.
The microprocessor will not assume the idle state under any of the following conditions:
- If the hood, fifth bow or tonneau cover is between the two end positions.
When the microprocessor is in the idle state it will not be possible to establish communication between the control module and an ISAT Scan Tool. In such case one of the window lift switches, for instance, could be activated to "wake up" the processor.
Power Supply and Grounding
The control module is supplied with power on pin 20 (K20) from the +30 circuit via maxifuse No.5 and on pin 9 (K20) from the +15 circuit via fuse No.19.
The control module is grounded as follows:
- Power ground on pin 10 (K20). Grounds motors.
- Signal ground on pin 18 (K42). Grounds the control module processor and the potentiometers. Chassis ground. The control module casing must be connected to the chassis to minimize the risk of interference with other systems.
Main Motors
The hood is raised and lowered by means of two d.c. motors located adjacent to the hood's main pivot brackets, one on each side of the car. These motors drive toothed segments, each connected by a lever to the rear rails of the hood mechanism.
The motors can be run in either direction by reversing the polarity of their power supply connections. When operating the hood the motors are supplied with 12v from pin 1 (K20) of the control module for raising it and from pin 11 (K20) for lowering it. If the motors stall; the control module incorporates a current-limiting circuit.
A potentiometer which senses the position of the hood is located adjacent to the left-hand main motor.
Fifth Bow Motors
The fifth bow is raised and lowered by means of toothed segments driven by two d.c. motors located adjacent to the fifth bow's mountings in the hood mechanism, one on each side of the car. The motors can be run in either direction by reversing the polarity of their power supply connections. When operating the fifth bow the motors are supplied with 12v from pin 13 (K20) of the control module for raising the it and from pin 14 (K20) for lowering it. If the motors stall, the control module incorporates a current-limiting circuit. A potentiometer which senses the position of the fifth bow is located adjacent to the right-hand motor.
Fifth Bow Latch Motor
A d.c. motor opens and closes the latches which secure the fifth bow to the tonneau cover. Mounted on the underside of the tonneau cover, the motor is connected to the two latches of the fifth bow by latch operating rods. Via cables from the latches, the latch motor also operates the access flaps at the front of the tonneau cover.
The motor can be run in either direction by reversing the polarity of its power supply connections. When operating the latches the motor is supplied with 12v from pin 12 (K20) of the control module for closing them and from pin 2 (K20) for opening them. If the motor stalls, the control module incorporates a current-limiting circuit.
Two microswitches which indicate whether the fifth bow is latched or not are mounted adjacent to the fifth bow latches.
Tonneau Cover Motor
A d.c. motor raises and lowers the tonneau cover. The motor is mounted in the boot on the right-hand side and connected to the tonneau cover hinge by a linkage system.
By means of cables the motor also opens and closes the latches securing the tonneau cover at the front. The motor can be run in either direction by reversing the polarity of its power supply connections. When operating the tonneau cover the motor is supplied with 12v from pin 16 (K20) of the control module for raising it and from pin 17 (K20) for lowering it. If the motor stalls, the control module incorporates. a current-limiting circuit.
A potentiometer adjacent to the motor senses the position of the tonneau cover.
Two microswitches which indicate whether the tonneau cover is latched or not are mounted adjacent to the tonneau cover latches.
Potentiometers
The hood-operating system incorporates three potentiometers, the purpose of which is to provide the control module with information on the exact positions of the hood, the fifth bow and the tonneau cover. The control module needs this information in order to control the raising and lowering movements of the hood.
All three potentiometers operate in the same way. Each potentiometer is connected by an arm directly to the relevant component. When the hood system is operated, a sliding contact is pulled along the carbon tracks in the potentiometer, thus changing its resistance. The control module senses this as a change in the voltage on pin 2 of the potentiometer. By measuring this voltage the control module can determine the position of the component in question. A 5v supply is applied to pin 1 of the potentiometers from pin 15 of the control module (K42). Pin 3 of the potentiometers is grounded via pin 29 of the control module (K42). Potentiometer resistance is obtained from pin 2 of the potentiometers and supplied to the control module on the following pins:
- Pin 30 (K42) - main motor potentiometer
- Pin 31 (K42) - fifth bow potentiometer
- Pin 32 (K42) - tonneau cover potentiometer
In order to maintain the best possible electrical contact in the potentiometer connectors, the control module applies a current of 12v to their contacts from pins 15, 30, 31 and 32 (K42) to burn off any impurities on them. This is done for 500 ms before the control module assumes the idle state. To ensure efficient burn-off of the contact surfaces, two zener diodes in each potentiometer are connected between pins 1 and 3 and between pins 2 and 3.
These zener diodes have a breakdown voltage of 6.2v so that when a higher voltage is applied to them their resistance is extremely low. When the control module applies a burn-off current of 12v the zener diodes short the voltage to ground. The burn-off current is conducted directly to the potentiometer connections.
After any work on the hood operating system entailing the removal of the control module, any potentiometer or the hood itself, the end positions of the potentiometers must be programmed in the control module. This should also be done after adjusting the hood or tonneau cover. Testing and Inspection
Main Motor Potentiometers
The main motor potentiometer is located adjacent to the left-hand main motor and indicates the position of the hood.
Fifth Bow Potentiometer
The fifth bow potentiometer is located adjacent to the right-hand fifth bow motor.
Tonneau cover Potentiometer
The position of the tonneau cover is indicated by a potentiometer located adjacent to the tonneau cover motor.
Microswitches
The hood operating system incorporates seven microswitches having the following functions:
- Two microswitches on the windscreen frame indicate whether or not the hood is mechanically latched to the windscreen frame.
- Adjacent to the fifth bow's left-hand latch is a microswitch which indicates whether or not the fifth bow is latched to the tonneau cover.
- Two microswitches in the tonneau cover latch indicate whether or not the tonneau cover is latched to the body.
- Two microswitches on the hood stowage bag indicate whether or not the stowage bag is in its lower position.
Pins 1 and 3 of the microswitches are connected to common voltage outputs on the control module. The control module applies one voltage to pin 1 and another voltage to pin 3. When the microswitch is actuated, the contact arm of the switch makes contact with pin 3 and when the microswitch is not actuated it makes contact with pin 1.
Via pin 2 the microswitches are each connected to a separate input on the control module. By measuring the voltage on pin 2 the control module can determine whether the microswitch is actuated or not. When the position of the microswitch does not coincide with the position indicated by the potentiometer, the TSAS control module sends a signal to the SID which then sounds a buzzer and displays an error message.
Communication With The SID
If the TSAS control module detects a fault in the system when operating the hood, it will immediately stop all hood. Movement and send a signal to the SID (Saab Information Display) which then sounds a buzzer and displays an error message. The signal goes from pin 11 (K42) of the TSAS control module to pin 5 of the SID. The SID command "DATA FROM TSAS" in the "READ VALUES" menu shows the current messages from the TSAS control module. The Saab 900 Cabriolet has the following CHECK messages:
Emergency Hood-Raising
It is not normally possible to operate the hood or tonneau cover by hand. This is due to the EMF (electromotive force) that builds up in the motors when an attempt is made to change their position. To enable the hood to be raised (closed) even when there is a fault in the system, such as a flat battery, the hood operating system incorporates an emergency hood-raising function. An emergency operating handle is located behind the rear-seat backrest on the right-hand side. Moving this handle from the vertical to a horizontal position activates the emergency hood-raising function. The circuits for the hood's main motors and fifth bow motors are broken by switches on the emergency handle at the same time as the tonneau cover motor is pressed out of engagement with the toothed segment driving the tonneau cover.
Emergency hood raising is carried out as follows:
- Move the emergency operating handle to a horizontal position.
- Raise the tonneau cover.
- Raise the hood without latching it to the windscreen frame.
- Lower the tonneau cover.
- Lower the fifth bow as far as it will go.
Important: When the emergency hood-raising function is used, the fifth bow cannot be latched in position. It is held in place by the EMF that builds up in its motors when the emergency operating handle has been returned to a vertical position.
- Press the tonneau cover down as far as possible while pulling up the emergency operating handle.
- Latch the hood to the windscreen frame.
Resetting
- Remove the luggage compartment trim on the right-hand side and, if necessary for easier access to the tonneau cover motor, also the right-hand rear light cluster.
- Press the tonneau cover motor back into the toothed segment driving the tonneau cover.
- Obtain readouts of the diagnostic trouble codes.
- Rectify the indicated trouble.
Important: It is not possible to lower (open) the hood by means of the emergency hood operating function.
Speed Signal
The car must be stationary before the hood can be operated. The TSAS control module determines this through information received from the ABS control module which measures the speed (max. about 3 km/h) of the right-hand rear wheel. The signal goes from pin 19 of the ABS control module to pin 12 (K42) of the TSAS control module.
Boot Lid
To avoid damage being caused to the hood or boot lid, the TSAS control module limits the possibility of releasing the boot lid lock by means of the button in the driver's door. The release button is connected via pin 19 (K20) to a relay in the control module. Pressing the button causes the relay to operate if the conditions described below are fulfilled. The control module then applies current to the boot lid lock motor via pin 18 (K20).
Releasing the boot lid by pressing the button in the driver's door is possible only when:
- The hood is raised fully.
- The hood is lowered fully and the ignition is switched on.
Operation of the hood is also affected by the position of the boot lid. The control module determines via the boot lighting switch whether the boot lid is open or closed. If it is open, the hood cannot be operated. If the "ROOF" button is pressed the control module will send a signal to the SID which then sounds a buzzer and displays the "CLOSE TRUNK LID" message.
Cars With An Anti-Theft Alarm
On model year 1995 cars equipped with an anti-theft alarm the boot lid cannot be opened by the remote control unit when the hood is down (open).
On the other hand, the boot lid can be opened by the remote control unit on model year 1996 and later cars equipped with an anti-theft alarm even when the hood is in the lowered position (down).
When the button on the remote control unit is pressed the anti-theft alarm's control module applies current from pin 23 directly to the boot lid tack motor. This function could give rise to certain problems in connection with work involving different hood components.
Important: Never use the remote control unit to open the boot lid while work involving hood components is being performed.
It work is being carried out on any hood component and the fifth bow and tonneau cover are caused to assume a vertical position with the ignition switched off at the same time as the boot lid is released by means of the remote control unit, it will not be possible to operate the hood or close the boot lid as there will not be enough force to lower the boot lid.
One possibility is to use the ISAT scan tool to operate the motors necessary for lowering the tonneau cover and then close the boot lid.
Alternatively, ask an assistant to press the boot lid down so that the hood can be operated until the tonneau cover closes and then close the boot lid.
Window Lifts
The window lifts are operated by five switches arranged in a group on the center console. These switches are connected to the TSAS control module which controls operation of the window lift motors. There is a switch for each window lift and a common switch for simultaneous operation of all four window lifts.
The switch buttons are supplied with power from the +54 circuit via fuse 7.
While the hood is being raised, the control module lowers the windows a few centimeters to prevent the hood from catching on any of them.
It is not possible to operate the window lifts from any of the five switches while the hood is being raised.
ACC
If the hood is towered with the ignition on or is already down when the ignition is switched on, the TSAS control module will send a signal to the SID which then sends the "TOP OPEN" signal to the ACC control module.
The signal goes from pin 11 (K42) of the TSAS control module to pin 5 of the SID.
The ACC system is set as follows:
- "AUTO" goes out.
- The temperature reading disappears and is replaced by a figure which shows the position. of the air-blending flap in steps from 1 to 10. 10 denotes hot and 1 denotes cold. Positions LO and HI for maximum cold and maximum heat are also provided.
- Fan speed is set to what it was when the hood was last up, except in positions LO and HI where fan speed is increased automatically, and this appears in the display.
- The air distributor moves to the floor position when the air blending flap is between 1 and 10. In the LO position the air distributor moves to the dashboard position and in the HI position it moves to the defroster/floor position.
- A/C is switched on.
- The electrically heated rear window is disabled.
All manual functions except the electrically heated rear window can be selected.