SPN 3510 - FMI 4 (Fault Code 187)

SPN3510 FMI4
Sensor Supply 2 Circuit - Voltage Below Normal or Shorted to Low Source

Sensor Supply Voltage

Fault Code: 187
PID(P), SID(S): S211
SPN: 3510
FMI: 4/4
Lamp: Amber

REASON: Low voltage detected at the sensor supply number 2 circuit.

EFFECT: Possible reduced engine performance.

Circuit Description:
The sensor supply 2 circuit of the engine control module (ECM) provides a 5 volt supply to various sensors on the engine harness. Refer to the wiring diagram for sensor supply identification.

Component Location:
Sensor Supply 2 originates in the Engine Connector portion of the ECM. It supplies 5 volts to sensors in the engine wiring harness.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the sensor supply 2 signal voltage was out of range low.
Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE lamp 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 2 circuit.
• The backup camshaft position sensor will not be functional.

Conditions for Clearing the Fault Code:
• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
• The "Reset All Faults" command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults.

Shop Talk:
• Low 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.

Read More:
SPN 175 - FMI 4 (Fault Code 213)
SPN 175 - FMI 3 (Fault Code 212)


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