Cummins ISC CM2150 (2007-09) Fault Code: 687 PID: 103 SPN: 103 FMI: 1 Turbocharger 1 Speed – Data Valid But Below Normal Operating Range – Moderately Severe Level. Low turbocharger speed detected by the ECM.

Verify the 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, calibrate the ECM.

This fault can possibly come active if the ECM senses engine speed while at the same time a turbocharger speed signal is less than 600 rpm.

Possible causes:

1)Damaged turbocharger speed sensor
2)Damaged engine harness
3)Damaged alternator (EMI or internal short)
4)Damaged ECM.

This fault becomes inactive any time the speed signal from the turbocharger speed sensor returns.

If the fault occurs intermittently, look for causes of intermittent open or short circuits in the turbocharger speed sensor circuit (including the speed sensor pigtail connector).

For the code to clear, the ratio of boost pressure to ambient pressure must be above 1.19:1 for at least 30 consecutive seconds. This condition can only be achieved during a test drive when the engine is under load. Operating the engine at idle or high idle while stationary will not create enough load to maintain boost pressure at 1.19 times ambient pressure for 30 consecutive seconds.

Although it is possible for a damaged ECM to be the root cause of this fault code, it is highly unlikely and ECM replacement should only be considered as a last resort if no other repairs are successful in clearing the fault code.

In very rare cases, it has been shown that the turbocharger can cause this fault code to come active and turbocharger replacement may be the only way to clear the fault code.

Possible repairs:

1)Replace the turbocharger speed sensor.
2)Replace the alternator.
3)Replace the ECM.