SPN 103 - FMI 2 (Fault Code 686)

SPN103 FMI2 (Turbocharger 1 Speed - Data Erratic, Intermittent, or Incorrect)
Fault Code 686
ISB, ISC, and ISL with CM2150 - Turbocharger 1 Speed Circuit

Fault Code: 686
PID(P), SID(S): P103
SPN: 103
FMI: 2/2

REASON: Turbocharger 1 Speed - Data Erratic, Intermittent, or Incorrect. An invalid turbocharger speed signal has been detected by the ECM.

EFFECT: None on performance. The ECM uses an estimated turbocharger speed.

Circuit Description:
The turbocharger speed sensor is a variable reluctance speed sensor. It consists of a coil of wire and an iron core. The target on the turbocharger shaft is a ground flat in the center of the shaft. As the flat on the turbocharger shaft spins past the speed sensor, a signal is generated. The electronic control module (ECM) interprets this signal and converts it to a turbocharger speed reading.

Component Location:
The turbocharger speed sensor is mounted in the center housing of the turbocharger.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
The ECM detects that the turbocharger speed is above the maximum limit set in the calibration.

Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• The ECM will estimate the turbocharger speed.

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

This fault code is logged when the ECM detects a turbocharger speed that is greater than the speed that is physically achievable by the turbocharger. Usually this indicates a faulty sensor or incorrect speed signals from the turbocharger speed sensor. This fault can be caused by failures in the following components:
• Turbocharger speed sensor
• Engine harness
• ECM power supply or grounds
• Electronic vehicle accessories which emit excessive electromagnetic interference.

This fault becomes inactive any time the ECM detects a valid turbocharger speed. If the fault occurs intermittently:
• Look for causes of intermittent open circuit or short circuits in the turbocharger speed sensor circuit (including the speed sensor pigtail connector)
• Look for sources of electronic noise such as poorly installed vehicle electronic components
• Be sure that the vehicle chassis grounds are in good condition
• Be sure that the ECM power supply and ground circuits are in good condition and that this power supply is not shared with other vehicle electronics.

Read More:
SPN 167 - FMI 1 (Fault Code 598)
SPN 167 - FMI 18 (Fault Code 597)


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