F722932 Force SPACER

System Operation
The PEEC III 3406 Diesel Truck Engine is an electronically-controlled 3406. PEEC III controls fuel rate and timing electronically instead of using flyweights and linkages. The electronics also replaces the mechanical fuel-air ratio control, torque control group, and various adjustment screws.PEEC III uses several sensors as inputs to control two basic functions: rack and timing. Operation of each of these are similar. PEEC III decides where it wants to position the rack or timing advance. It then varies the voltage to the solenoid (BTM) to move the rack or timing to the desired position. Position sensors tell PEEC III when rack or timing is at the desired position.Electronic Controls
The electronic controller consists of two main components: the Electronic Control Module (ECM) and the Personality Module. The ECM is the computer which controls the 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.Rack Controls
The rack mechanism on a PEEC III engine is very similar to a mechanical 3406 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 III servo spool is moved by a solenoid (BTM) rather than by a linkage controlled by flyweights and springs.PEEC III determines a "desired rpm" based on the throttle position, vehicle speed, customer specified parameters, and certain diagnostic codes. The PEEC III governor tries to maintain the desired rpm by sensing actual engine speed using the engine speed sensor, then controlling the rack to achieve the desired rpm.PEEC III RPM Control Logic To move the rack, PEEC III adjusts the voltage to the rack solenoid (BTM) to increase rack. More voltage results in more rack. PEEC III knows how far the rack went by reading the rack position sensor. PEEC III increases the voltage to the rack solenoid until it senses the rack is in the desired position.PEEC III Electronic Governor PEEC III 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 a mechanical engine FARC; when PEEC III 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 springs 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 3406 mechanical engine, except the Timing solenoid (BTM), instead of the flyweights, controls timing advance. PEEC III adjusts voltage to the timing solenoid to change timing advance. More voltage results in more timing advance. PEEC III knows how much advance was achieved by reading the timing position sensor. PEEC III simply increases voltage to the timing solenoid until it senses that the timing advance is in the desired position.PEEC III Timing Advance Programmable Parameters
Certain parameters that affect PEEC III 3406 Diesel Engine operation may be changed with electronic service tools (either the ECAP or DDT). The parameters are stored in the ECM, and are protected from unauthorized changes by passwords.These parameters are either "System Configuration Parameters" or "Customer Parameters". System Configuration Parameters are those that effect horsepower family or emissions. Customer Parameters are those that affect cruise control, vehicle speed limits, progressive shifting, horsepower rating within a family, engine protection mode, and PTO operation.Some parameters may affect engine operation in ways a driver does not expect without adequate training. These may lead to power or performance complaints, even when the engine is performing to specification.Passwords
"System Configuration Parameters" are protected by factory passwords. 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 Configuration Parameters."Customer Parameters" are protected by customer passwords. The customer passwords are programmed by the customer. Either the ECAP or DDT may change customer Parameters (although if a customer programs his password with alphabetic characters using an ECAP, only an ECAP can change Customer Parameters, since the DDT does not have alphabetic characters).Self-Diagnostics
The PEEC III electronics have some ability to diagnose itself. When a problem is detected, a diagnostic code is generated and the diagnostic lamp is turned on. In most cases, the code is also stored in permanent memory in the ECM.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 section on "Troubleshooting Diagnostic Codes" in this manual for more details.Codes stored in memory are called LOGGED. Since the problem may have been temporary or may have been repaired since the time it was logged, logged codes don't necessarily mean something needs to be repaired. Instead they are meant to be an indicator of probable causes for intermittent problems. In addition, some logged codes record "events", rather than failures. Codes not requiring passwords to clear are automatically deleted after 100 ECM hours. See the section on "Troubleshooting Diagnostic Codes" in this manual for more details.PEEC III System Component Diagram PEEC III Engine Diagram Electrical Connectors and Functions
Service Tools
The Caterpillar Service Tools for the PEEC III system are designed to help the service technician analyze and locate faults or problems within the system. Their use is required in order to perform sensor calibrations electronically, and to read or change engine parameters. The basic tools have small plug-in modules, called service Program Modules (SPM), to adapt the basic tools to the specific Caterpillar electronic engine application.The two principle tools are the Electronic Control Analyzer Programmer (ECAP), and the Digital Diagnostic Tool (DDT). Both are able to Communicate with the PEEC III Electronic Control Module to read Diagnostic Codes, to read the various sensor output signals