Convertible Top Control Module: Testing and Inspection
Programming of the control module must be carried out after the following work has been performed on the system:
- Potentiometer replacement
- Control module replacement
- Removal/fitting of complete hood
Important: Mechanical adjustment must be carried out before electrical adjustment with the ISAT Scan Tool.
It may sometimes be necessary to reprogram the control module when certain other components have been removed This is specified after each such component replacement in the "Removal and fitting" section.
Using an ISAT scan tool, it is possible to program each potentiometer individually. This is done by first obtaining readings of all the potentiometer positions and making a note of them and then carrying out the programming as described in the following.
Important: This description applies to control module 45 58 144, 46 10 812 and 46 95 961. If the car is equipped with control module 43 07 450, it should be rectified.
Mechanical End Positions
The hood system consists of three main moving parts: the hood (A), the fifth bow (B) and the tonneau cover (C). The maximum movement of each of these three parts is limited mechanically. Some of the mechanical end positions can be adjusted within certain limits. For instance, the end position of the hood when raised can be adjusted by means of a mechanical stop situated where the hood mechanism is attached to the car body.
Programmed End Positions
The TSAS control module operates the motors which drive the various parts of the hood mechanism up and down. When any part reaches a mechanical end position, the control module must receive a signal to this effect. Otherwise it will continue to run the motor against the mechanical end position, finally breaking the circuit to the motor and generating a diagnostic trouble code for too high current consumption.
To provide the control module with continuous information on the exact position of the hood mechanism, the mechanism is equipped with three potentiometers (position sensors): one for the hood, one for the fifth bow and one for the tonneau cover. The potentiometer signals a value of between 0 and 255, depending on the position of the hood mechanism. The potentiometer values corresponding to the mechanical end positions are programmed in the TSAS control module. The control module then knows when the mechanical end positions are reached and can stop driving the motors.
Interaction Between The Mechanical And Programmed End Positions
From what has been said on the previous pages it will be evident that the programmed end positions must never be outside the mechanical ones. If they were outside, the control module would continue to drive the motor in question even though the mechanical end position had been reached. Finally, the control module would break the circuit to the motor and generate a diagnostic trouble code for too high current consumption.
Instead, the control module should be programmed with end positions which are just inside, or in certain cases the same as, the mechanical end positions. The control module will then stop operating the motor in question before the mechanical end position is reached and the movement will come to a smooth stop. For instance, if the main motor potentiometers signal a value of 204 when the hood has reached the upper mechanical end position, that is to say when it is fully raised, the control module should be programmed with the value 201. By subtracting 3 units, the main motors will stop driving the hood mechanism just before the mechanical end position is reached and the hood will come to a smooth stop against the windscreen frame.
For lowering (opening) the hood, 1 unit should instead be added to the value signaled by the potentiometer when the hood has reached the lower mechanical end position. If the lower end position corresponds to a potentiometer value of 49, the control module should be programmed with the value 50. When the hood is lowered (opened) the control module will then count down from potentiometer value 201 (programmed upper end position) to 50. At this point the control module will stop operating the main motors driving the hood and the hood can descend to the mechanical end position (potentiometer value 49) by its own weight. In the ISAT Scan Tool the upper end positions are called "HIGH LIMIT" and the lower end positions are called "LOW LIMIT".
Overlapping Positions
To ensure that raising and lowering the hood will be carried out quickly and smoothly, the TSAS control module must be able to control two different movements of the hood system simultaneously. For this to be possible without the different parts of the hood system colliding with each other, the TSAS control module must know exactly when to start the different movements.
To provide the control module with this information, for the different parts of the hood system over and above the two end positions. These values are called overlapping positions, one high and one low. For
instance, when the hood reaches the upper overlapping position the TSAS control module starts the fifth bow's downward movement. The functions of the different overlapping positions will be evident from the table below.
It is extremely important for the overlapping positions to be correctly programmed in the control module. If incorrect values are entered, the different parts of the hood system could collide with each other and sustain irreparable damage.
1 High overlapping position, hood
- When the main motor reaches this position on raising the hood, the control module starts the fifth bow's downward movement.
2 Low overlapping position, hood
- When the main motor reaches this position on lowering the hood, the control module checks that the fifth bow is in its high position. If it is not, the control module will stop further movement of the hood and raise the fifth bow to its high position.
3 High overlapping position, tonneau cover
A On lowering the hood:
When the tonneau cover motor reaches this position, the fifth bow starts its downward movement (past the tonneau cover) to pass above the head restraints.
B On raising the hood:
When the tonneau cover motor reaches this position, the main motor starts its upward movement.
4 Low overlapping position, tonneau cover
- When the tonneau cover closes and reaches this position during raising of the hood, the fifth bow starts its downward movement.
5 High overlapping position, fifth bow
- When the fifth bow motor reaches this position on lowering the hood, the tonneau cover latch opens.
6 Low overlapping position, fifth bow
- Here the main motor starts its downward movement on lowering the hood at the same time as the fifth bow reverses its direction of movement.
Points To Remember When Programming
The following points should be borne in mind before programming is started:
- The car should stand on a level surface.
- The hood mechanism should be correctly adjusted:
Correct programming of the potentiometer values is dependent on the mechanical adjustment of the hood mechanism. It is therefore extremely important for the hood mechanism to be correctly adjusted mechanically when programming is started. A condition for this is that the hood's stop position when raised is correct. If it is not, the programming will almost certainly not be correct either. Similarly, it is just as important for new potentiometer values to be programmed after major mechanical adjustment of the hood mechanism.
- Alerting the control module:
When the control module has been inactive for more than three seconds it will assume the idle state. Before communication can be established between the ISAT scan tool and the control module, the control module must first be "woken up". Programming and Relearning
- Tip the rear-seat backrest forwards:
During the course of programming, the rear window might come into contact with the head restraints on the rear-seat backrest. To avoid damage to the rear window and consequent replacement of hood fabric, all programming should be carried out with the backrest tipped forward.
- Operating the hood in connection with programming:
Note the difference between operating the hood with the ISAT scan tool and operating it with the ROOF button on the center console: With the ROOF button the hood moves to the programmed position while with the ISAT scan tool it moves to the mechanical stop. Unless otherwise stated, the ISAT scan tool should be used when the hood mechanism is operated during programming. When the hood is operated, keys F3 (UP) and F4 (DOWN) should be held down for at least five secondsafter all movement of the hood mechanism has ceased. This is to ensure that the end positions have definitely been reached.