Circuit DescriptionThe sensor supply 2 pin of the electronic control module (ECM) provides volt for the camshaft position sensor, intake manifold pressure/temperature sensor, crankcase pressure sensor, engine oil pressure sensor (if equipped), turbocharger compressor intake pressure/temperature sensor (if equipped), and barometric pressure sensor (if equipped).
Component LocationSensor supply 2 is located in the ECM and provides a 5 VDC 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 running.
Conditions for Setting the Fault CodesThe ECM detects that the sensor supply 2 signal voltage is less than a 4.8-VDC for more than 1 second.
Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.The backup camshaft position sensor will not be functional.A default value is used for all other sensors on the sensor supply 2 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 engines.
Shop TalkLow voltage on the +5 volt supply line can be caused by a short circuit to ground in a supply line, a short circuit between a supply line and a return line, a malfunctioning sensor, or a malfunctioning ECM power supply.
During the fault code response test outlined for each sensor connected to sensor supply number 2, Fault Code 187 must be active before unplugging each sensor. If the fault code is not active, but can be easily duplicated by operating the engine, the following can be performed:
Operate the engine under the conditions that will cause Fault Code 187 to become active, even if it logs for a short period of time. Unplug one sensor at a time until Fault Code 187 stops logging under the test conditions. Each sensor can be unplugged with the engine running. Note: The engine may not start if the camshaft position sensor is unplugged
Possible Cause:1) Camshaft Position Sensor failure2) Intake manifold pressure/temperature sensor failure3) Crankcase pressure sensor failure4) Turbocharger compressor intake pressure/temperature sensor failure5) Engine oil pressure sensor failure6) Barometric air pressure sensor failure7) Engine harness8) ECM calibration