Auto Shutdown Relay

The Auto Shutdown (ASD) relay is located in Intelligent Power Module (IPM) in engine compartment, near the battery. See Figure and Figure . The ASD sense circuit informs the PCM when the ASD relay energizes. A 12-volt signal at this input indicates to the PCM that the ASD has been activated. This input is used only to sense that the ASD relay is energized. When energized, the ASD relay supplies battery voltage to the fuel injectors, ignition coils and the heating element in each oxygen sensor. When energized, the ASD relay provides power to operate the injectors, ignition coil, generator field, oxygen sensor heaters, EGR solenoid and also provides a sense circuit to the PCM for diagnostic purposes. If the PCM does not receive 12 volts from this input after grounding the ASD relay, it sets a Diagnostic Trouble Code (DTC). The PCM energizes the ASD anytime there is a crankshaft position sensor signal that exceeds a predetermined value. The ASD relay can also be energized after the engine has been turned off to perform an O2 sensor heater test.