Digital Triggers
WARNING: This page is about a different car, the 2003 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
Digital Triggers handle inputs that are already digital but need conversion from voltage levels to 1 or 0 before being processed by the Input/Output unit.
Here, a pull-up or pull-down must be used so the input goes to a specific position when voltage or ground is not applied to the pin. There is no point in grounding a pin to indicate if the door has been opened if the pin is already at 0 V.
In fault tracing, one is often instructed to connect a jumper to a digital control module input with pull-up to ground. The diagnostic tool then changes the value between, for example, Off and On. This shows that the lead is whole.