The Ignition Bypass function allows for support of older GM ignition systems which used this function. This type of ignition system has the trigger signal being sent directly to the ignitor module which then fires the coil. To allow the ECU to take control of ignition timing it will “bypass” the ignitor and send the signal to the ECU for ignition timing processing. The ECU then sends a signal back to the ignitor with the ignition timing adjusted and then the ignitor module fires the coil. Without the Ignition Bypass function enabled, the timing will be controlled only by the ignitor module at a fixed value.
DPO-1 should be selected for this function due to it having a programmable Pull Up voltage. The Pull Up should be set to 5.00, and the Active State set to High for the Ignition Bypass to function correctly.