Diagnostics

Diagnostics--The Trionic control module communicates with a Scan Tool via pin 33. Communication is two-way and so involves both input and output signals.

The Scan Tool can communicate with the Trionic system when the ignition is switched on and the engine running but also for 15 minutes after the ignition has been switched off. Obviously, no functions requiring a +15 or +54 supply can then be activated.

When the engine is running, the diagnostics function has low priority in the Trionic control module. At high engine speeds the Trionic system therefore breaks off communication with the Scan Tool.

The Scan Tool display shows "NO CONTACT" and the Trionic system will have to be selected again if it is desired to reestablish communication.

The DTC memory of the Trionic control module will be erased if the control module is de-energized.

Lamp Flash Codes--To comply with current legal requirements in the United States (OBD I), it must be possible to obtain emission-related trouble code readouts by means of flash codes on the CHECK ENGINE lamp (MIL).

When the ignition has been switched on and the lamp test has been performed (3 seconds), flash codes will be activated automatically if any DTCs are stored in the memory. Engine Control Systems