SPN 677 - FMI 4 (Fault Code 585)

SPN677 FMI4 (Fault Code 585)
Starter Relay Driver Circuit - Voltage Below Normal or Shorted to Low Source

ISB, ISC, and ISL with CM2150 - Starter Relay Circuit

Fault Code: 585
PID(P), SID(S): S039
SPN: 677
FMI: 4/4

REASON: Starter Relay Driver Circuit - Voltage Below Normal or Shorted to Low Source. Low voltage detected at starter lockout circuit.

EFFECT: The engine will not have starter lockout protection.

Circuit Description:
The starter lockout relay is controlled by the electronic control module (ECM) through the starter lockout relay signal circuit. The relay prevents the starter from being engaged when the engine is running. The relay return circuit is dependent on OEM wiring. It may be wired back to the ECM on some vehicles or wired to the chassis or block ground on others. Consult the OEM wiring diagram for return circuit details. The starter lockout relay circuit utilizes a pulse width modulated (PWM) signal. A PWM signal is a pulsed voltage signal between 0 VDC and system voltage. The frequency of
the pulsed voltage signal is dependent on the application requirement.

Component Location:
The starter lockout relay is installed by the vehicle OEM. Refer to OEM troubleshooting and repair manual for exact location.

Conditions for Running the Diagnostics:
This diagnostic runs when the keyswitch is in the ON position and when the PWM device is being energized or deenergized. In some cases the diagnostics may also run at some fixed intervals.

Conditions for Setting the Fault Codes:
The starter lockout relay circuit PWM signal is detected to be greater than 0 VDC when the PWM signal 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 starter lockout feature will be disabled.

Conditions for Clearing the Fault Code:
The ECM will turn off the amber CHECK ENGINE light and the fault code state will become inactive immediately after the diagnostic runs and passes. The fault code can also be cleared using INSITE™ electronic service tool.

Shop Talk:
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

The ECM monitors the voltage level on this circuit. If it detects a low voltage when the signal is commanded on, it records this fault code. This fault code can be caused by a short circuit to ground in the starter lockout relay, OEM harness, or connectors.

Read More:
SPN 677 - FMI 3 (Fault Code 584)
SPN 157 - FMI 2 (Fault Code 554)


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