Circuit Description

The Powertrain Control Module (PCM) receives the following ignition inputs from the ignition switch:

• Ignition 0 signal.
• Ignition 1 signal.
• Crank signal

The PCM uses a Class II Ignition mode message and the voltage input from 2 separate systems to test the ignition 0 circuit. If PCM detects an improper ignition 0 signal, DTC P1634 will set.