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Automatic transmission control module (TCM)

Automatic transmission control module (TCM)




DRIVE

When the gear selector in automatic cars is set to any position other than P or N, B+ will be applied to the Trionic control module pin 14. The control module will then open the idle speed control valve slightly more to compensate for the increase in load. Pin 14 is not connected on cars with manual gearbox.

The ignition will also be retarded temporarily depending on the throttle position when any gear other than P or N is selected to protect the automatic transmission.

Diagnosis


• There is no diagnosis for the electric circuit.

DRIVE can be read with the diagnostic tool.


CHECK ENGINE Request

If an emission-related fault should occur in the automatic transmission, its control module will send a 2 Hz PWM signal to the Trionic control module pin 61 and Trionic will then turn on the CHECK ENGINE lamp. When the ignition is turned to ON, the transmission control module will send a ground pulse for 1 second to check its function.

Diagnosis


• A diagnostic trouble code will be generated for a short circuit to ground but not for an open circuit.



Torque reduction when shifting gear

The automatic transmission control module grounds Trionic control module pin 13 when shifting gear. The Trionic system will then retard the ignition to improve shifting comfort and to protect the automatic transmission.

During shifting, the ignition timing will be between 17 BTDC and 10 ATDC depending on the engine speed and load.

Diagnosis


• There is no diagnosis for the electric circuit.

Torque reduction can be read with the diagnostic tool.




Torque reduction when braking

When the brake pedal is depressed, B+ will be applied to control module pin 15. The ignition will be retarded if both the brake pedal and the accelerator pedal are depressed and the engine speed is below 3000 rpm. This is to protect the transmission from "stalling".

Diagnosis


• There is no diagnosis for the electric circuit.

Brake can be read with the diagnostic tool.