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Transmission 45
9-5
Control modules
The transmission control module primarily
controls
• Shift points
• System pressure
• Lock-up engagement (fixed or slipping)
The control module has two 38-pin connections
and is located behind the glove box in the
passenger compartment. It is programmed for
one of the engine variants B235E/R or B308E
and is only to be used in the Saab 9-5 together
with the relevant engine variant. The control
module is delivered unprogrammed when
purchased as a spare part and must therefore be
programmed for the correct engine type using
Tech 2 and the SPS procedure. The control
module receives information from a number of its
own sensors as well as from other electronic
systems. This information is processed by the
control module for controlling the current gear
and shift points based on the selected driving
program (NORMAL, SPORT or WINTER).
Gear changing takes place when the control
module acts on solenoid valves S1, S2, S3, S4
and S5, which are mounted in the transmission
valve body. The control module also determines
if and when the torque converter lock-up is to be
engaged based on a certain combination of
solenoid valve settings. Three linear solenoids
are mounted in the valve body and control the
lock-up (SLU), system pressure (SLT) and the
clutch disc pressure (SLS).
When the ignition switch is turned to the ON
position, the control module will be activated and
turn on the CHECK GEARBOX lamp as a
function check. If no faults are found, TCM will
turn off the lamp after three seconds.
In the event of a fault in any of the inputs/outputs,
the transmission will go into Limp-home mode. All
control module functions will then be disengaged
or an emergency operation program will be
activated. The car can then be driven but with
limited shifting capability.
TCM also takes into consideration any wear that
may be present in the gearbox, which ensures
smooth gear changing even when the gearbox is
worn. This adaptive system means the TCM
compares the current gear changing performance
with a gear changing matrix in the software and
"learns" whatever each gear changing situation
requires with respect to pressure/time in order to
perform the gear change comfortably. Because of
this, the TCM must be reset (using Tech 2) after
carrying out repairs, or exchanging the gearbox
or TCM, and after SPS programming.
The control module can be SPS programmed
using the diagnostic instrument.