WOODWARD GOVERNOR SERVICE MANUAL FOR CATERPILLAR G330 Caterpillar

Operation Overview

Usage:

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Read this entire manual and all other publications pertaining to the work to be performed before installing, operating, or servicing this equipment. Practice all plant and safety instructions and precautions. Failure to follow instructions can cause personal injury and/or property damage.

The Digital Min/Max ProAct(TM) control system is equipped with an overspeed shutdown feature that operates to protect against runaway or damage to the engine. Failure to properly install and operate the control system could result in possible personal injury or loss of life.

Application Specific Operation and Features

The 8400-504 and 8400-510 Digital Min/Max ProAct(TM) (DMMP) controls are designed to operate on the Caterpillar G3306 engine in natural gas fueled vehicle applications.

Basic Minimum and Maximum Operation

All DMMP controls have the same basic minimum and maximum governing functions and direct foot pedal control between the speed limits. The control provides precise idle control over a wide load range experienced during idle conditions. An idle speed curve is available to help vary the idle speed at various loads. The control also provides precise speed control at high idle. The maximum governor provides speed control at maximum rated speed for the engine during normal control operation. The maximum governor has two speed setpoints like the minimum governor. See Chapter 4 for a more detailed description of the minimum and maximum speed governor setpoints.

PTO Governor

The DMMP control provides a PTO (power take-off/fast idle) governor for controlled speed operation to run a PTO device, or to run the engine at a fast idle speed. The control has a contact to select the PTO governor. When the PTO is selected, the control disables the foot pedal, preventing the engine speed from changing. The PTO may be selected only when the transmission is in neutral.

Foot Pedal Operation

The foot pedal, with idle validation contact, controls the actuator position when the engine speed is not being controlled by the governor. The foot pedal is part of the drive-by-wire control system that eliminates the mechanical linkages and cables connecting the foot pedal to the throttle body. The foot pedal provides the DMMP control with a 0 to 5 volt signal. The DMMP control uses that signal to control the position of the actuator/throttle. The idle validation contact provides an additional protection feature. When the foot pedal is at the minimum stop, the contact is open and disables the foot pedal input (which activates the minimum governor). This prevents engine speed changes due to foot pedal position sensor errors, and also serves as a safety feature should any foot pedal wires break.

NOTE: This application comes preset from the factory with the idle validation contact disabled. The default mode uses the minimum foot pedal setting plus 5% to trigger the functions normally triggered by the contact. The foot pedal mode is set in the FOOT PEDAL header. Use of this feature is dependent on the foot pedal manufacturer and model.

Actuator and Position Feedback Operation

The DMMP control uses a ProAct(TM) I actuator. The ProAct I has position feedback that makes the actuator movement fast and accurate. Use care to protect the wiring between the DMMP control and the actuator. If any of the five wires to the actuator breaks or makes a poor connection, the DMMP will force the actuator to the minimum position.

Also make sure the wiring matches the labeled polarity (+/-) on the actuator and the position feedback. Verify proper actuator rotation and operation before starting the engine. The position feedback signal uses a three-wire signal (5 Vdc positive, 0 sense, and negative return) to determine the position. No other connections should be made to the position feedback signal. The sense voltage is measured with respect to the return, and should be 2.0 ± 0.2 Vdc at minimum actuator position and 3.0 ± 0.2 Vdc at maximum actuator position.

Actuator Demand Signal

The actuator demand output signal from the DMMP control is used for factory testing only. However, it may be used to help tune the dynamic response of the control system by monitoring with an analog voltmeter. The signal is a 0 to 5 Vdc output that is inversely proportional to the actuator command from the microprocessor.

SAE 1587-1708 Serial Network

The DMMP has an SAE 1587-1708 serial data link to allow it to communicate with other vehicle electronic control modules that also use this network. The network also provides the only means to change and monitor setpoints inside the DMMP control.

You can connect to the data link with an application-specific hand-held programmer or with a PC (IBM-compatible personal computer) and serial adapter. The PC Service Tool software is used to communicate with the DMMP control. At present, there are no cartridges for hand-held devices to tune any DMMP control setpoints. A generic SAE 1587-1708 hand-held tool can retrieve and clear any available fault codes. See Chapter 4 for more information.

Figure 1-4 is a diagram showing a serial adapter example interface.

Engine and Vehicle Sensor Supply

The DMMP control has two 5-volt outputs that are used to power sensors on the engine and sensors located on the vehicle. [The actuator position sensor uses its own 5-volt supply.] The two 5-volt outputs combined can supply up to 100 mA. If the load increases beyond that, the 5-volt output will be pulled down and will trigger a fault. The sensor ground is used as the reference for all voltage measurements coming into and out of the DMMP control. NOTE: Sensor ground is not battery ground, and they should never be tied together.

The DMMP control has one vehicle sensor in this application - the foot pedal position sensor. There are no engine sensors used at this time.

Diagnostics and Flash Codes

The DMMP control has failure diagnostics and fault modes. If the control detects a fault, it turns on the fault indicator lamp. On request, it sends a specific "flash code" to the fault indicator. Each flash code is a two-digit number. To see any active fault codes, press the foot pedal twice within 0.5 second. The fault indicator flashes the codes in sequence. For example, the fault indicator would flash a "32" fault code by turning the indicator on three times with a half-second pause between each flash, then it would wait one second, then flash two times with a half-second pause between each flash (see Figure 1-1). If there is more than one fault, the control would send the next flash code after a two-second pause. See Chapter 7 for more information. Faults can also be read directly off the PC software diagnostics screens, or with a generic J1587-1708 service tool and cartridge.

Figure 1-1. Flash Code Pulses