PACCAR PX-9 CM2350 (2013-17) 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

Reason:
Idle Shutdown Vehicle Accessories Relay Driver Circuit – Voltage Above Normal, or Shorted to High Source. Open circuit or short to voltage source detected at the idle shutdown vehicle accessory/ignition bus relay circuit.

Effect:
Vehicle accessories or ignition bus loads controlled by the idle shutdown relay will not power up.

Circuit Description:
The Engine 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:
The 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 or when the engine is running.

Conditions for Setting the Fault Codes:
1) The Engine Control Module (ECM) detected the idle shutdown relay pulse width modulated (PWM) signal was at system voltage when the pulse width modulated (PWM) signal was Action Taken When the Fault Code is Active
2) The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
3) The accessories controlled by the idle shutdown relay will be disabled.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) 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 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:
1) ECM Idle Shutdown feature set up incorrectly.
2) Open circuit in the idle shutdown relay, OEM harness, or connectors.
3) 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.

Possible Causes:
1) Inactive fault codes
2) Faulty ECM
3) Damaged relay and circuit