Electronic Control System Signature, ISX and QSX15 Engines – 101-007   Electronic Controlled Fuel System

General Information

The Signature, ISX, and ISM engine control system is an electronically operated fuel control system that also provides many operator and vehicle or equipment features.

The base functions of the control system include:

• Fueling and timing control
• Limiting the engine speed operating range between the low- and high-idle set points
• Reducing exhaust emissions while optimizing engine performance.

The system can also control the engine brakes, up to two cooling fans, an air compressor, and a Top 2 transmission.

ECM Inputs

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.

The electronic control module (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 the INSITE™ electronic service tool and some other vehicle controllers, such as transmissions, antilock braking system (ABS), automatic slip reduction (ASR), electronic dash displays, etc., through the new SAE J1939 datalink or the older SAE J1708 datalink.

Some vehicles and equipment will have 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, such as transmission shifting, antilock braking, etc.

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

1. Coolant Temperature Sensor
2. Intake Air Temperature Sensor
3. Intake Manifold Pressure Sensor
4. Oil Pressure/Temperature Sensor
5. Crankshaft Engine Position Sensor (Signature, ISX, QSX15 only)
6. Camshaft Engine Position Sensor
7. Ambient Air Pressure Sensor
8. Fuel Supply Pressure Sensor (Signature, ISX, QSX15 only)
9. Front and Rear Rail Pressure Sensors (Signature, ISX, QSX15 only)
10. Fuel Inlet Restriction Sensor
11. Water-in-Fuel Sensor
12. Wet Tank Pressure Sensor.

The following inputs are provided by OEM-selected devices:

1. Accelerator Pedal Position Sensor
2. Idle Validation Switch
3. Engine Brake Selector Switches
4. Coolant Level Sensor
5. Vehicle Speed Sensors
6. Feature Control Switches, Cruise Control Switches
7. Air Conditioner Pressure Switch
8. Remote Throttle
9. Remote PTO
10. Top 2 Autoshift Transmission Gear Position Sensor.

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

Diagnostic Fault Codes

The control system can show and record operation anomalies that present themselves as fault codes. These codes will make troubleshooting easier. The fault codes are recorded in the ECM. They can be read using the fault lamps in the cab, using a diagnostic switch, or with INSITE™ electronic service tool.

There are two types of fault codes:

• Engine electronic control fault codes (fault has been detected with the engine or control system)
• Information codes (event that can provide important information has occurred with the engine or control system).

All fault codes recorded will either be active (fault code is currently active on the engine) or inactive (fault code was active at one time but is not currently active).

The WARNING light is yellow and indicates the need to repair the fault at the first available opportunity.

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 shut down until the fault can be repaired.

The MAINTENANCE lamp will illuminate, indicating some form of maintenance is required. This lamp could indicate water in the fuel filter, low coolant level, high coolant temperature, high intake air temperature, or high oil temperature.

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

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

Turn the vehicle keyswitch to the ON position.

If no active fault codes are recorded, both red and yellow lights come on, go out in sequence, and remain off.

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

The fault code will flash in the following sequence:

First, a WARNING (yellow) light will flash. Then, there will be a short 1- or 2-second pause after which the number of the recorded fault code will flash in STOP (red). There will be a 1- or 2-second pause between each number. When the number has finished flashing in red, a yellow light appear again. The three-digit code will repeat in the same sequence.

To skip to the next fault code, move the set/resume switch (if equipped) momentarily to the increment (+) position. The operator can go back to the previous fault code by momentarily moving the set/resume switch (if equipped) to the decrement (-) position. If only one active fault is recorded, the same fault code displays continuously when either (+) or (-) switch is depressed.

The explanation and correction of the fault codes is in Section TF of the Signature, ISX, and QSX15 Engines and the ISM and QSM11 Engines, Electronic Control System, Troubleshooting and Repair Manuals.

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

Fault Code Snapshot Data

This is additional fault code information that can be obtained by using INSITE™ electronic service tool. The snapshot data records the value or state of the control system sensors and switches at the time a fault occurred. This data is stored for the first occurrence of the fault, since it was last cleared, and the most recent occurrence. This data can be very valuable when trying to recreate or determine engine operating conditions at the time of a fault.

Maintenance Monitor

CAUTION  The maintenance monitor is designed to alert the operator of the need for a routine maintenance stop. Maintenance records must still be maintained for historical purposes.

CAUTION  The maintenance monitor uses data received from the vehicle speed sensor (VSS) to determine distance and data from the ECM to determine the amount of fuel burned. Whenever a VSS or battery voltage fault has occurred, the maintenance monitor data can be inaccurate.

The maintenance monitor is an optional feature that will alert the operator when it is time to change oil and perform any other simultaneous maintenance tasks. The maintenance monitor continuously monitors the distance the vehicle has traveled, the time the engine has been operating, and the amount of fuel burned to determine when it is time to change oil.

The alert to remind the driver of an oil change is a flashing MAINTENANCE lamp for the first 8 seconds after the keyswitch is turned on. This flashing lamp does not indicate a fault has occurred.

The operator must still be alert for any indications that the engine needs other service.