18 spd eaton fuller autobox

[donniemnemonic]

Hi all.
Have an 18 spd eaton fuller automatic box model number RTLO-20918A-AS2 driven by a detroit engine on an argosy freightliner. Have managed to find the gearbox wiring but I am having problems finding the oem wiring for the shift select lever. It is mounted on the steering column and labeled smart shift has a selector button that switches between 4 stages namely R, N, D, and L. Under the steering column it has three wires going into it that are all yellow in color. The problem I am having is that the box will upshift from 1 to 6 normally then fails to pick up from 7 upwards. Have cleared the fault codes but after a drive fault codes 72, and 91 reappear but are inactive, can someone help.

[talmadge]

Fault code 91 is batt voltage ( it can cause fault 71 , failed to select rail) check ecm power wire and ground, take a 20 amp fuse and unplug the ecm power harness at the ecm insert fuse it should blow it. if it dont recheck pwr and grd wires. if that is good with veh parked in neutral hit the up button twice and see if the range box goes in to high side, if it dont make sure you have 80 psi at the regulate. Hope that helps

[jtr8178]

Hi all.
Have an 18 spd eaton fuller automatic box model number RTLO-20918A-AS2 driven by a detroit engine on an argosy freightliner. Have managed to find the gearbox wiring but I am having problems finding the oem wiring for the shift select lever. It is mounted on the steering column and labeled smart shift has a selector button that switches between 4 stages namely R, N, D, and L. Under the steering column it has three wires going into it that are all yellow in color. The problem I am having is that the box will upshift from 1 to 6 normally then fails to pick up from 7 upwards. Have cleared the fault codes but after a drive fault codes 72, and 91 reappear but are inactive, can someone help.

What is the last 6 of the VIN #? I can get you some wiring schematics from Freightliner.