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Electronic control module

Electronic control module


Electronic control module

Saab Trionic principally controls


• ignition (by means of the ignition discharge module)

• fuel injection (which is sequential)

• boost pressure (by means of a solenoid valve)

The Trionic electronic control module has a 70-pole terminal and is located at the right-hand A-pillar. When the powertrain is removed, the ECM terminal and its wiring are guided out through the bulkhead partition.

The ECM has a 32-bit processor which can perform 2 million calculations per second.

A number of sensors supply information to the ECM, which processes these using matrices which have been stored in the ECM after engine operation has been optimized. Examples of such important matrices are ignition timing matrices, fuel matrices and boost pressure matrices.

The ECM is programmed for the B204L and is only to be used for this engine in the Saab 900.

The ECM may be damaged by electrostatic discharges or shorting of any of the ECM's outputs, and great care must therefore be taken whenever handling the ECM, for example in fault diagnosis, e.g. with a BOB.



The electronic control module is continuously supplied with +30 voltage and loses adapted values and diagnostic trouble codes stored in its memory if this voltage disappears.

The ECM is adjusted for a voltage between 8 and 16 V during driving.

When the ignition is switched on, the ECM is activated and pre-injection takes place provided certain conditions are met. The ECM then waits for pulses from the crankshaft position sensor.


The main measured quantity for fuel injection comes from the manifold absolute pressure sensor.

There are substitute functions for all sensors apart from the crankshaft position sensor.

After the ignition has been switched off, all sensors which are supplied with 5 V remain activated for 15 minutes. During this time it is also possible to carry out scan tool diagnostics. After 15 minutes, global adaptation of the main fuel matrix takes place and only the memory is then activated.

Adaptation is important for performance, drivability, fuel consumption and emissions. The ECM must therefore not be unnecessarily disconnected or in any other way de-energized.