Trouble Godes - diagramas.diagram...

Electronically controlled transmissions
Most electronically controlled transmission systems have sensors monitoring load, selector lever position, gear change
strategy program, transmission output shaft speed, engine crankshaft speed, and speed of brake and throttle operation.
Signals from these are sent to a combined engine and transmission (powertrain) control module or a separate
transmission control module (TCM).
These inputs are processed by the transmission control module (TCM) and appropriate control outputs are sent to the
transmission.
Where a separate engine control module (ECM) and transmission control module (TCM) are used, these are linked and
data is shared between the two.
The self-diagnosis fault memory will log trouble codes when certain control module inputs or outputs are outside the
programmed parameters and may invoke 'limp home' substitute values for any out-of range signals.
There are several types of transmission that can have electronic control with self-diagnosis trouble code output:
Automatic
Semi-automatic
4 wheel drive
Automatic transmission: usually comprise a torque converter driven by the engine crankshaft and an epicyclic gearbox
with four or five forward ratios.
The mechanical operation of the transmission is actuated hydraulically, but with electronic controls, enabling several
different change patterns to be selected by the driver (e.g. sport, economy etc.). Smoother gear changes (using torque
reduction by retarding the ignition timing) and better matching of gear ratios to available torque, are also advantages.
Lower powered (and often front-wheel drive) cars may be fitted with a continuously variable transmission. This may be
driven via a torque converter, multi-plate clutch or magnetic coupling.
In this form of transmission a steel band is driven by a variable diameter drum and the output is from a similarly variable
diameter drum. It has no fixed ratios and finds its own 'ideal' ratio from the inputs of speed and load sensors.
Semi-automatic transmission: these are a comparatively recent innovation and use a conventional gearbox (helical spur
gears) with hydraulically operated clutch. Electronics are used to ensure smooth gear changes, prevent excessive engine
speeds and to 'blip' the throttle during down changes.
4 wheel drive: vehicles with a Haldex coupling between the front and rear wheels have electronic control of the centre
differential. Sensor inputs from the wheel speed sensors, stop lamp switch and other control modules (via a CAN data
bus) are used to govern the power distribution between the front and rear wheels.
The transmission systems covered by this manual have associated trouble codes which will be logged under certain fault
conditions.
These codes may be part of the engine management trouble code output (in the case of powertrain control modules) or
they may be accessed separately - refer to model-specific chapters.
Fig. 2
1 Selector lever
2 Selector position switch 3
3 Mode selection switch
4 Kickdown switch 8 15 13
5 Throttle position (TP) sensor
6 Engine torque signal
7 Engine speed (RPM) signal
8 Output shaft speed (OSS) sensor
9 Solenoid valves
10 Transmission control module (TCM)
1 1 Engine control module (ECM)
12 Data link connector (DLC)
13 Torque converter
14 Ignition coils
15 Epicyclic gearbox