More DSG details; from "Self-Study Program 990193" here, page 20
0B5 S Tronic Transmission
Integrated Sensors
The transmission control module, the four distance sensors and the two hydraulic pressure sensors are combined as a non-separable unit. Two temperature sensors are integrated into the TCM. One sensor is positioned to supply precise ATF temperatures.
The other sensor is integrated directly into the processor and measures critical component temperatures. The two temperature senders monitor each other for plausibility. Electronics temperature monitoring is very important so that temperature reduction measures can be made quickly, as needed. Besides safety, ATF temperature is relevant to both clutch control and hydraulic control. For this reason, ATF temperature is also a key factor in control and adaptation functions. Automatic Transmission Hydraulic Pressures Sensors 1 and 2 are utilized for clutch pressure monitoring and for adaptation of the primary pressure and sub-gearbox pressures.
Four distance sensors determine the position of each selector rail/shift fork. The TCM requires this information to immediately diagnose non-allowed positions and to activate a “limp home” program, if necessary. An exact travel measurement is also essential for precision gear shifting. The various phases of the synchronization and gear shifting processes can then be activated sequentially.
A distance sensor consists of two Hall sensors and two permanent magnets which are attached to the selector rail. Depending on the position of the magnets in relation to the Hall sensors, the Hall sensors output a voltage which corresponds to the distance traveled. The travel signal is generated by evaluating both voltage signals.
Drive Position Sensor G676 is located in the gearbox and is an integral part of the sensor module. This is a contactless travel sensor which is used to determine the selector lever positions (P, R, N, D, and S). A permanent magnet exerting a magnetic force on the gear sensor is located on the parking lock lever. The parking lock lever is connected to the gear lever by a shaft. It is actuated by the selector lever by means of a selector lever cable.
Note: The transmission control module requires data on selector lever position to perform the following functions and generate the following signals and information:
• Information on driver input/vehicle operating state (forward, reverse, neutral) for activation of the clutches and gear selectors
• Information for selection of shift program “D” or “S”
• Signal for controlling the starter inhibitor
• Signal for controlling the P/N lock (shift-lock)
• Information for reverse gear (for example, back-up lights, Park Assist System, etc.)
• Control of the selector lever position indicator in the instrument cluster and gearshift mechanism
The position sensor is a PLCD travel sensor. The abbreviation PLCD stands for Permanent Magnetic Linear Contactless Displacement sensor and describes a contactless sensor which measures linear travel using a permanent magnet. The signal generated by this sensor is very important for gearbox control and is safety-critical. For this reason, G676 consists of two redundant sensors arranged in parallel. The TCM always evaluates both sensors.
Control Module Temperature Monitoring
High temperatures have a negative impact on the useful life and performance of electronic components. Due to the integration of the transmission control module into the transmission housing (lubricated by ATF), it is very important to monitor the temperature of both the electronics and ATF. When the temperature reaches approx. 275°F (135°C) (measured by one of the two temperature sensors in the transmission control module), the electronics must be protected against a further rise in temperature. When this threshold value is exceeded, the transmission control module initiates a reduction in engine torque to reduce heat input. Up to a temperature of approx. 293°F (145 °C), engine torque can be reduced gradually until the engine is at idle. When the engine is at idle, the clutches are open and there is no power transmission from the engine to the drive wheels. When the protective function is activated, an entry is made in the fault memory and the following text message is displayed in the instrument cluster: “You can continue driving to a limited extent.”
Clutch Protection
If the clutch cooling oil temperature exceeds a value of approx. 320°F (160 °C), as determined by G509, the clutch is within a critical temperature range that can damage it. These temperatures occur, for example, when accelerating on extreme gradients, when towing a trailer, or when the vehicle is held stationary on an uphill slope using the accelerator and the clutch without engaging the brake. As a safety precaution, engine torque is reduced when cooling oil temperature exceeds 320°F (160 °C.) If the cooling oil temperature continues to rise, engine torque is gradually reduced, sometimes to idle. When the engine is at idle, the clutches are open and there is no power transmission from the engine to the drive wheels. When the protective function is initiated, an entry is made in the fault memory and the following text message is displayed in the instrument cluster: “You can continue driving to a limited extent.” As an additional safety precaution, the clutch temperature is determined using a computer model. If the computed temperature exceeds a pre-defined value, the above mentioned precautions are taken.
“Limp Home” Programs
In the event of a malfunction, serious damage can be prevented and mobility preserved by means of “limp home” programs initiated by the transmission control module. In addition, there are also protective functions, which protect certain components against overload. In the event of certain pre-defined system malfunctions, the transmission control module shuts down the subgearbox in question and activates the relevant “limp home” program (driving with intact sub-gearbox).
1. Driving with sub-gearbox 1, sub-gearbox 2 shut down:
• Only gears 1, 3, 5, and 7* can be engaged (with interruption in tractive power)
• Backing up (reversing) is not possible
2. Driving with sub-gearbox 2, sub-gearbox 1 shut down:
• Only gears 2, 4, 6, and R* can be engaged (with interruption in tractive power).
3. Complete gearbox shutdown:In the case of serious faults
• for example, a faulty powertrain CAN, no identification by the immobilizer, or recognition of an incorrect ratio in the gear steps or in the final drive — the gearbox is completely shut down.
• The nature of the fault dictates which gears are still available. To be sure that components do not overspeed, certain gears are disabled depending on fault type. After ensuring that no gear is engaged in the deactivated gearbox, all gears of the intact subgearbox are shifted without any further restrictions.
Displays/Warnings
The 0B5 transmission features new information and warning technology in the instrument cluster, which will alert the driver to a system malfunction or the initiation of a protective function. The following warnings are displayed:
“Gearbox fault: You can continue Driving” appears when faults the driver may not notice are recognized by the transmission control module, which then activates a suitable substitute signal. These faults result in no, or only negligible, loss of performance. The purpose of the warning is to prompt the driver to take the vehicle to an Audi dealer at the next opportunity.
“Gearbox fault: You can continue driving to a limited extent only” appears when gearbox protection functions and faults result in a loss of performance. This can have the following effects:
• “Limp home” program: “Driving with sub-gearbox 2” is active. For example, gearshifts have interruptions in tractive power (even-numbered gears only)
• Gearbox protective function is active, but engine power is reduced because the engine torque reduction function is also active
• No power transmission to the driving wheels after stopping
• The engine can no longer be started
“Gearbox fault: You can continue driving to a limited extent only No reverse gear” appears when the “limp home” program, “Driving with sub-gearbox 1,” is active because reverse gear cannot be selected at the same time. Text messages disappear after five seconds, and are displayed again for five seconds at “ignition ON.” Yellow warning symbols are permanently displayed.
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Originally Posted by SwankPeRFection
. Maybe a Tiptronic isn't so bad after all, lol!
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