42881A 1 Mercury SHIFT RAIL

(PEEC) System Overview
The 3412 PEEC Industrial Engine is an electronically-controlled 3412. PEEC controls fuel rate electronically. The electronics replace the mechanical fuel-air ratio control, torque control group, and various adjustment screws.PEEC uses several sensors as inputs to control the rack function. PEEC decides where it wants to position the rack. It then varies the voltage to the solenoid (or "BTM") to move the rack toward the desired position. Position sensors tell PEEC when the rack is at the desired position.Electronic Controls
The PEEC controller consists of two main components: the Electronic Control Module (ECM) and the Personality Module. The Electronic Control Module (ECM) is the computer which controls a PEEC engine. The Personality Module is the software which controls how the computer behaves. The two must be used together -neither can do anything by itself.When the power switch(es) is first turned on, the personality module sends the ECM through some self-checks. Until the self-checks are complete, PEEC limits rpm to 1700 rpm, power to about half of normal, and timing advance to zero. It takes about 8-10 seconds to complete the self-checks, during which time the operator should not advance the throttle. If the throttle is advanced during this time, the self-checks are postponed until it returns to low idle to allow the checks to finish. If electrical power to PEEC is briefly interrupted during operation, PEEC goes back through these self-checks to ensure proper operation of its circuits.Rack Controls
The rack mechanism on a PEEC engine is very similar to a mechanical 3412 engine. The fuel injection pump is nearly identical; the rack is moved by a servo valve which receives oil pressure from the fuel injection pump. However, the PEEC servo spool is moved by a solenoid or (BTM) rather than by a linkage controlled by flyweights and springs.PEEC comes up with a "desired rpm" based on the throttle position, Customer Specified Parameters, and certain diagnostic codes. The PEEC governor tries to maintain the desired rpm by sensing actual engine rpm using the engine speed sensor, then controlling the rack to achieve the desired rpm. To move the rack, PEEC adjusts the voltage to the rack solenoid (BTM) to increase rack. More voltage results in more rack. PEEC knows how far the rack actually went by reading the rack position sensor. PEEC increases the voltage to the rack solenoid until it senses the rack is in the desired position (Reference "Rack Pos" on ECAP Status Screen). PEEC sets certain limits on rack motion. "FRC Rack" is a rack limit based on Fuel-Air Ratio Control, for emissions purposes. It works similar to mechanical engine FARC; when PEEC senses a higher boost pressure (more air into cylinder), it increases the FRC Rack limit, which allows more fuel into the cylinder. "Rated Rack" is a rack limit based on horsepower of the engine. It is similar to the rack stops and torque spring on a mechanical engine. It provides horsepower and torque curves for a specific engine family and rating. All of these limits are programmed by the factory into the personality module.Timing Advance Controls
The timing advance mechanism is the same as the 3412 mechanical engine. It is centrifugal only, and IS NOT part of the PEEC system.Programmable Parameters
Certain parameters that affect PEEC engine operation may be changed through electronic service tools. The parameters are stored in the ECM, and are protected from unauthorized changes by passwords.The section on "Programming PEEC Parameters" in this manual has more details on specific parameters and how to program them.Passwords
"System Configuration Parameters" are protected by factory passwords. System Parameters are those that affect horsepower family or emissions. Factory passwords are calculated on a computer system available only to Caterpillar dealers. Since factory passwords contain alphabetic characters, only the ECAP may change System Parameters."Customer Specified Parameters" are protected by customer passwords. Customer Parameters are those that affect idle speed, Top Engine Limit, and System ID. The customer passwords are programmed by the customer. The ECAP may change Customer Parameters and a customer may use alphabetic and/or numeric characters in his password.The section on "Programming PEEC Parameters" in this manual has more details on when passwords are needed and how to obtain them.Self-Diagnostics
PEEC has some ability to diagnose itself. When a problem is detected, a diagnostic code is generated and the diagnostic lamp is turned on. The code may also be stored in permanent memory in the personality module.Diagnostic Codes that represent current faults are called ACTIVE. They indicate that a problem of some kind currently exists. They should always be serviced first. See the Troubleshooting Diagnostic Codes section in this manual for more details.Diagnostic Codes stored in memory are called LOGGED. The problem may have been temporary or may have been repaired since the time it was LOGGED. Therefore, LOGGED diagnostic codes don't necessarily mean something needs to be repaired. They are meant to be an indicator for when intermittent problems exist. In addition, some logged diagnostic codes record "events", rather than failures. See the section on "Troubleshooting Diagnostic Codes" in this manual for more details.(PEEC) System Component Diagram
For Electrical Schematic, refer to Form No. SENR4657.Electrical Connectors and Functions
PEEC Service Tools
The Caterpillar Service Tool for the PEEC system is designed to help the service technician analyze and locate faults or problems within the system. It is required to perform sensor calibrations electronically, and to read or change programmable engine parameters.The tool has small plug-in modules, called Service Program Modules (SPM), to adapt the basic tool to a particular engine or application.The principal tool is the Electronic Control Analyzer and Programmer (ECAP). It is able to communicate with the PEEC Electronic Control Module to:* Program Customer Specified Parameters.* Display and clear ACTIVE or LOGGED Diagnostic Codes.* Calibrate sensors.* Measure duty cycle (or pulse width) of Pulse Width Modulated (PWM) Sensors (ECAP requires 8C9801 PWM Signal Adapter for this).In addition, the ECAP can:* Program System Configuration Parameters (necessary to replace an ECM).* Perform functions requiring factory passwords.* Display status of up to 10 sensors or switches simultaneously.* Can