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Cummins ISB CM850 (2003-06) Fault Code: 687 (ISB) PID: 103 SPN: 103 FMI: 18 Turbocharger number 1 speed low – warning level. Low turbocharger speed detected by the ECM. This fault will become active if the engine is running and the ECM detects boost pressure and engine speed but no turbocharger speed signal. Possible causes: 1)Turbocharger speed sensor failure2)Engine harness failure3)ECM failure. This fault becomes inactive at key-on or any time the speed signal from the turbocharger speed sensor returns. If the fault occurs intermittently, Fault Code 2345 can also be in the ECM memory. Look for causes of intermittent...

Cummins ISB CM850 (2003-06) Fault Code: 687 (ISC) PID: 103 SPN: 103 FMI: 1 Turbocharger Number 1 Speed Low – Data Valid but Below Normal Operational Range – Moderately Severe Level. Low turbocharger speed detected by the ECM. This fault may come active if the electronic control module (ECM) senses boost pressure and engine speed while at the same time a turbocharger speed signal is not present. Items that can fail and cause this fault code include: 1)Turbocharger speed sensor2)Engine harness3)Barometric pressure sensor4)Intake manifold pressure sensor5)ECM. This fault becomes inactive any time the speed signal from the turbocharger speed sensor...

Cummins ISB CM850 (2003-06) Fault Code: 688 PID: 98 SPN: 98 FMI: 0 Engine Oil Level ? Data Valid But Above Normal Operational Range ? Most Severe Level. High oil level has been detected by the oil level sensor. Fault code 688 indicates that the oil level in the engine is much higher than the recommended oil level. Other causes: 1)The engine may have been overfilled with oil during the most recent oil change2)The fuel system may be leaking into the lube oil system. (Check for fuel system faults or use fluorescent fuel system dye to identify leaks)3)The cooling system...

Cummins ISB CM850 (2003-06) Fault Code: 689 PID: 190 SPN: 190 FMI: 2 Engine Crankshaft Speed/Position – Data Erratic, Intermittent, or Incorrect. Loss of signal from crankshaft sensor. This fault code is recorded when the electronic control module (ECM) does not receive a signal from the crankshaft engine speed sensor, or the signal it receives is degraded. Possible causes: 1)Open circuit on the supply, signal, or return circuits in the sensor, engine harness, or ECM2)Short circuits to ground or return circuits in the sensor, engine harness, or ECM3)Short circuits to a voltage source in the sensor, engine harness, or ECM4)Damage...

Cummins ISB CM850 (2003-06) Fault Code: 691 PID: SPN: 1172 FMI: 3 Turbocharger Number 1 Compressor Inlet Temperature Sensor Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the turbocharger compressor inlet air temperature circuit. The turbocharger inlet air temperature sensor shares return wires in the engine harness with other sensors. An open return can cause multiple fault codes to be active. Before troubleshooting Fault Code 691, check for multiple fault codes. An extension harness between the main engine harness and the turbocharger compressor inlet temperature sensor may be used depending on the turbocharger...