Here it is. This is a Monster Garaged 16 year old garbage truck. It took me from April 10 to May 10 2006 to finish this beast. It was formerly a mechanical STC Pt pump Cummins L-10 275 mated to an Allison HT700 hydraulic automatic transmission that is cable shifted and had a cable step modulator feedback to the mechanical throttle linkage. This was a forty thousand dollar repower to comply with California Air Resources Board emissions regulations, part of which was paid for by the State of California. Thank you taxpayers. The task was to repower this old 1990 bin front loader garbage truck with a brand new computerized digital full authority EGR ISM CM875 and figure out how to be able to step modulate the transmission in the absense of a mechanical throttle linkage, making the mechanical step modulating cable not possible to use. The transmission was a like for like swapout of the HT700 Allison. The old engine is pictured below. The step modulator was converted from cable actuation to a 12 volt servo motor that mounted on the transmission right where the cable was formerly attached. Step modulation (usually called "kick down") is an "either-or" function, in other words, it is either 12 volts on (actuated), or 12 volts off (relaxed), and nothing in between. The electric modulator is actuated "on" when the throttle reaches 80 percent increasing transient, and it de-actuates at 65 percent throttle decreasing transient. It lets the transmission know what the driver wants to do and where the engine is. It is the electronic equivalent of the cable modulator that attaches to the throttle linkage in all-mechanical setups. ISB, ISC, and ISL engines have this function that can be programmed and has an output pin to operate the modulator as mentioned above. Everybody at Cummins figured the function was not included because nobody would be fool enough to mate an ISM engine type to a cable shift old-school Allison that has no data link capabilities. The assumption is that...
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