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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 3406B 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 or (BTM) rather than by a linkage controlled by flyweights and springs.PEEC III comes up with 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. 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 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 FRC; 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 3406B 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. Programmable Parameters
Certain parameters that affect PEEC III 3406B 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, and PTO operation.Some parameters may affect engine operation in ways a driver does not expect