Circuit DescriptionThe sensor supply 1 of the electronic control module (ECM) provides a 5 volt supply for the Exhaust Gas Recirculation (EGR) differential pressure sensor, exhaust gas pressure sensor, EGR valve position sensor, and EGR orifice pressure sensor (if equipped).

Component LocationSensor supply 1 is located in the ECM and provides a 5 volt supply to various engine sensors. The supply voltage is spliced off in the engine harness to each sensor it supports.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position or when the engine is operating.

Conditions for Setting the Fault CodesThe ECM detects that the sensor supply 1 signal voltage is less than 4.75-VDC for more than one second.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE light and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.A default value is used for all of the sensors on the sensor supply 1 circuit.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On Board Diagnostic (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkLow voltage on the +5 volt supply wire can be caused by a short circuit to ground in a supply wire, a short circuit between a supply wire and a return wire, a malfunctioning sensor, or a malfunctioning ECM power supply.

Possible Cause:1) EGR differential pressure sensor failure2) Exhaust gas pressure sensor failure3) EGR valve position sensor failure4) EGR orifice pressure sensor failure5) Aftertreatment fuel pressure sensor failure6) Engine harness7) ECM calibration