Feesability of ditching the autoshift?

You need to verify first the current wire scheme for the vehicle speed sensor. Some oem's have a single sensor with 2 leads-1 runs the transmission and 1 runs the gauge. Some have 2 sensors-1 for the trans and 1 for the gauge and some have 1 sensor that feeds the transmission-transmission feeds the engine-engine feeds the gauge. So you might not have to wire at all. Every oem does it differently not to mention there are different generations of transmissions. All you need to do is go into a cummins dealer and have the transmission parameter turned from auto to manual and then set the vehicle speed parameters (ppm's). The hardest thing to overcome for most is the wiring. Most people don't realize the transmission takes over control of the engine brakes. You either need to eliminate the engine brake/transmssion harness or just bypass it at the relay. Same with the neutral start circuit. Hope this sheds a little light on the subject.

 

usually pair of wires are used. On trucks with auto wires run to lower mounted TCU and speed signal is transmitted to upper TCU with propriate can, TCU trasmits speed via J1708 and J1939 to other units.

On trucks with manual tranny (but not on volvo and not with tachografs) VSS is wired directly to engine ECU

 

:smt023

 

Just buy a truck equipped the way you want it. You are EASILY going to spend that $5-10k in reduced price if you plan on switching over the trans and engine. Just a whole lot of headache for more money.