Cummins ISX12 CM2250 (2010-12) Fault Code: 338 PID: SID 87 SPN: 1267 FMI: 3 Idle Shutdown Vehicle Accessories Relay Driver Circuit- Voltage Above Normal or Shorted to High Source

Circuit Description
The Electronic Control Module (ECM) Idle Shutdown feature has an optional parameter for a shutdown accessory relay. When this parameter is set to ?Installed?, the ECM sends a signal to energize the relay and turn off vehicle accessories during idle shutdown events. The idle shutdown relay return circuit varies by Original Equipment Manufacturer (OEM). The return circuit can be returned to the ECM through the ECM Return (General) or connected directly to ground. Refer to the OEM service manual to determine grounding configuration.

Component Location
This idle shutdown relay location varies by OEM. Refer to the OEM service manual to determine the location.

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

Conditions for Setting the Fault Codes
The idle shutdown relay Pulse Width Modulated (PWM) signal is detected to be at system voltage by the ECM when the PWM voltage is turned off.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
The accessories controlled by the idle shutdown relay will be disabled.
Conditions for Clearing the Fault Code
To 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.
The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults.

Shop Talk
The ECM monitors the voltage level on this circuit. If it detects a voltage when the signal is commanded OFF, it records this fault code. This fault code can be caused by:

ECM Idle Shutdown feature set up incorrectly.
Open circuit in the idle shutdown relay, OEM harness, or connectors.
Short circuit to a voltage source in the OEM harness or relay.
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Cause:
1) OEM harness
2) ECM calibration