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CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – 101-007   Electronic Controlled Fuel System

General Information

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The ISX CM871 and ISM CM876 electronic control modules (ECM) are electronically operated fuel control systems that also provide many operator and vehicle features.

The base functions of the control system include fueling and timing control, limiting the engine speed operating range between the low and the high idle set points and reducing exhaust emissions while optimizing engine performance. The system also controls the engine brakes.

The control system uses inputs from the operator and its sensors to determine the fueling and timing required to operate at the desired engine speed at the required emissions level.

ECM Inputs

The ECM is the control center of the system. It processes all of the inputs and sends commands to the fuel system, vehicle and engine control devices.

The ECM performs diagnostic tests on most of its circuits and will activate a fault code if a problem is detected in one of these circuits. Along with the fault code identifying the problem, a snapshot of engine operating parameters at the time of fault activation is also stored in memory.

Active fault codes will cause a diagnostic lamp to activate to signal the driver.

The ECM can communicate with service tools and some other vehicle controllers (such as transmissions, ABS, ASR, electronic dash displays and so on) through the SAE J1939 data link.

Some vehicles and equipment will have SAE J1939 networks on them that link many of the “smart” controllers together. Vehicle control devices can temporarily command engine speed or torque to perform one of its functions (that is, transmission shifting, anti-lock braking and so on).

The control system utilizes a number of sensors to provide information on engine operating parameters. These sensors include:

  • Engine coolant temperature sensor
  • Intake manifold air temperature sensor
  • Intake manifold pressure sensor
  • Engine oil pressure sensor
  • Engine speed (crankshaft position) sensor
  • Camshaft position sensor
  • Barometric pressure sensor
  • Rail fuel pressure sensor
  • Water-in-fuel sensor
  • Turbocharger speed sensor
  • Turbocharger compressor inlet air temperature sensor
  • Accelerator pedal/lever position sensor
  • Engine brake selector switches
  • Engine coolant level sensor
  • Vehicle speed sensors
  • Feature control switches (i.e. cruise control switches)
  • Fan control switch
  • Air conditioner pressure switch
  • Remote accelerator
  • Remote PTO.

NOTE: These inputs are application dependent. Some applications will not use all of these inputs.

Diagnostic Fault Codes

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The electronic engine control system can display and record certain detectable fault conditions. These failures are displayed as fault codes, which make troubleshooting easier. The fault codes are retained in the ECM.

There are two types of diagnostic codes:

  • Engine electronic control system fault codes are to inform the operator that there is a problem with the control system that will require troubleshooting.
  • Information and engine protection fault codes are to inform the operator that the control system has detected an engine condition outside the normal operating range.
  
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All fault codes recorded will either be active (fault code is currently active on the engine) or inactive (fault code was active at some time, but is not currently active).

The “Stop” light is red and indicates the need to stop the engine as soon as it can be safely done. The engine must remain shutdown until the fault can be repaired.

The “Warning” light is amber and indicates the need to repair the fault at the first available opportunity.

Maintenance type fault codes will flash the amber Warning light for 30 seconds after the keyswitch is turned to the ON position when one of the following occurs: maintenance is required (if Maintenance Monitor is turned on) or if water-in-fuel is detected.

NOTE: The names and colors of these lamps can vary with equipment manufacturer.

  
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Fault codes can be accessed in at least two different ways; using the electronic service tool, or fault code flash out.

To check for active engine electronic fuel system and engine protection system fault codes, turn the keyswitch OFF and move the diagnostic switch to the ON position.

  
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Turn the vehicle keyswitch to the ON position.

If no active fault codes are recorded, both lights will come on and stay on.

If active fault codes are recorded, both lights will come on momentarily then begin to flash the code of the recorded faults.

  
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The fault code will flash in the following sequence:

  • First, a WARNING (amber) light will flash.
  • Then there will be a short one or two second pause after which the number of the recorded fault code will flash in STOP (red).
  • There will be a one or two second pause between each number.
  • When the number has finished flashing in red, an amber light will appear again.
  
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The lights flash each fault code out three times before advancing to the next code. To skip to the next fault code, move the Increment/Decrement switch (if equipped) momentarily to the increment (+) position. You can go back to the previous fault code by momentarily moving the Increment/Decrement switch (if equipped) to the decrement (-) position. If only one active fault is recorded, the same fault code will continuously be displayed when either (+) or (-) switch is depressed.

The explanation and correction of the fault codes is in Section TF of this manual.

  
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When not using the diagnostic system, turn off the diagnostic switch.

  
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Throttle Activated Diagnostic Switch


The Throttle-Activated Diagnostic Switch feature is intended to eliminate the need for a dash-mounted diagnostic switch, which is used to activate the fault code flashout on the lamps. The fault code flashout will be activated through a simple sequence of throttle movements. When this feature is enabled, the engine is in stop state and the keyswitch is in the ON position. Every successive cycle of the throttle will lead to the next fault code to be flashed on the lamps, in the same manner as if the increment switch were depressed.

To activate this feature, the engine must be stopped and the keyswitch turned to the ON position. Then depress the accelerator pedal completely three times. The feature will then be enabled. Transitioning to the next fault code will happen automatically after the first fault code is flashed out twice or if the throttle pedal is cycled.

NOTE: There is an optional, error-sensitve mode for this feature. If any of the throttle-related errors occur, this feature will turn on the diagnostic switch automatically when the engine is stopped and the keyswitch is in the ON position. During this mode, only the increment switch can be used to flash out the next fault code.

  
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Engine Protection System

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 CAUTION 

When the red STOP lamp is illuminated, the driver/operator must pull to the side of the road, when it is safe to do so, to reduce the possibility of engine damage.

The ISX CM871 and ISM CM876 engines are equipped with an engine protection system. The system monitors critical engine temperatures and pressures, and will log diagnostic faults when an over or under normal condition occurs. If an out-of-range condition exists and engine derate action is to be initiated, the operator will be alerted by an in-cab Warning lamp. The Stop lamp will blink or flash when out-of-range conditions continue to worsen. The driver must pull to the side of the road, when it is safe to do so, to reduce the possibility of engine damage.

NOTE: Engine power and speed will gradually be reduced, depending on the level of severity of the observed condition. The engine protection system will not shut down the engine unless the engine protection shutdown feature has been enabled.

  
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Fault Code Snapshot Data

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When a diagnostic fault code is recorded in the ECM, the ECM input and output data is recorded from all sensors and switches. Snapshot data allows the relationships between ECM inputs and outputs to be viewed and used during troubleshooting.

Fault code snapshot data can only be viewed using INSITE™ electronic service tool.

  
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INSITE™ Description

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INSITE™ is an electronic service tool for the electronic engine control system. Use INSITE™ electronic service tool to:

  • program customer specified information into the ECM (Parameters and Features)
  • aid in troubleshooting the engine
  • change the engine power or rated speed calibration
  • transfer new or update calibration files to the ECM
  • create and view trip reports, etc.
  
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INSITE™ Monitor Mode

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The INSITE™ electronic service tool Monitor Mode is a useful troubleshooting aid that displays the key ECM inputs and outputs. This feature can be used to spot constantly or intermittently out-of-range values.

  
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Engine Monitoring System

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Exhaust Gas Treatment Fault Code and Maintenance Lamps


Depending on the vehicle manufacturer, a Cummins engine equipped with a Cummins® particulate filter can have up to two additional dash lamps and an additional switch for the ECM to provide feedback to the operator on the status of the aftertreatment system, along with the CHECK ENGINE and STOP ENGINE lamps.

  
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    Particulate Filter Lamp

  • Indicates the need for assistance in achieving regeneration.

    High Exhaust System Temperature Lamp

  • Indicates that high exhaust temperatures are due to the regeneration of the particulate filter.
  
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Engine Fault and Maintenance Lamps


The STOP or STOP ENGINE lamp is red and indicates the need to stop the engine as soon as it can be safely done. The engine must remain shut down until the engine can be repaired.

The WARNING or CHECK ENGINE lamp is yellow. When it illuminates, the engine is in need of repair at the first available opportunity.

The yellow lamp will flash for 30 seconds at key-on when one of the following occurs:

  • maintenance required (if Maintenance Monitor is enabled)
  • water-in-fuel is detected.

If the warning light flashes for 30 seconds at key-on and water is drained form the primary water-separating fuel filter then the secondary fuel filter must be replaced.

  
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Stationary Regeneration

 WARNING 

Exhaust outlet temperatures will reach 600°C [1112°F] during a normal stationary regeneration event. To avoid personal injury, do not touch the diesel aftertreatment parts.
  1. Make sure the parking brake is set, the transmission is in neutral or park, and wheel chocks are in place.
  2. There must not be any combustible material such as paper products, wood products, dry grass, or fuels within 2 feet of the exhaust outlet.
  3. If using an exhaust discharge pipe in a service bay, make sure it is capable of withstanding temperatures above 600°C [1112°F].
  4. There must not be any persons or animals within 1.5 m [5 ft] of the exhaust outlet during this process.

Stay with the vehicle to make sure these conditions are kept in place for the duration of the process. If these conditions change, stop the process and take corrective action(s) before continuing the process.

A stationary regeneration can be required on vehicles that have very light duty cycles and/or do not maintain exhaust temperatures that are high enough to regenerate the particulate filter.

A stationary regeneration can be performed in two ways:

  1. With vehicles equipped with a stationary regeneration switch that is enabled in the ECM, the vehicle can be parked in a safe location with the stationary regeneration switch turned on and the engine will operate in such a way to create enough heat to regenerate the particulate filter. The engine will automatically return to normal operating conditions when the particulate filter is regenerated.
  2. INSITE™ electronic service tool can be used to initiate the regeneration event and cause the engine to operate in such a way to create enough heat to regenerate the particulate filter. The engine will automatically return to normal operating conditions when the particulate filter is regenerated.

The regeneration can be discontinued by engaging the clutch, brake, or throttle pedals.

Aftertreatment Lamp Description

The engine ECM constantly monitors the condition of the Cummins® particulate filter. If the vehicle is operated in such a way that the engine is not able to regenerate the filter, the aftertreatment lamps will illuminate, indicating the need for the operator to take action. As the need to regenerate the particulate filter increases, the ECM will progressively notify the operator of the need and severity of the need. The table below indicates the different stages of lamps, the meaning, and the action required. How quickly the system steps through the levels of severity is dependant on the vehicle’s duty cycle.

    Illuminated High Exhaust Temperature Lamp

  • Meaning: High exhaust temperatures due to regeneration of the particulate filter.
    • Action To Take: Be sure that the engine exhaust pipe outlet is not directed at any surface or material that will melt under high temperatures or is combustible.

    Illuminated Particulate Filter Lamp

  • Meaning: The particulate filter needs to be regenerated at the next opportunity.
    • Action To Take: Change to a more challenging duty cycle, such as highway driving, to raise exhaust temperatures out of the engine for at least 20 minutes, or perform a stationary regeneration.

    Flashing Particulate Filter Lamp

  • Meaning: The particulate filter needs to be regenerated soon. The engine can be derated.
    • Action To Take: Change to a more challenging duty cycle, such as highway driving, to raise the exhaust temperatures out of the engine for at least 20 minutes, or perform a stationary regeneration.

    Illuminated Check Engine Lamp and Flashing Particulate Filter Lamp

  • Meaning: The particulate filter needs to be regenerated immediately. The engine will be derated.
    • Action To Take: Perform a stationary regeneration.

    Illuminated STOP ENGINE Lamp

  • Meaning: The particulate filter can no longer be safely regenerated. The engine will be severely derated.
    • Action To Take: Take the vehicle to an Authorized Cummins Repair Facility.
Last Modified:  13-Feb-2006
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Published by Jack

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