Eaton Fuller Advantage (2017) Fault Code: 71 PID: SPN: 560 FMI: 7 Unable to Disengage Gear: Mechanical System Not Responding

Overview:
The Fuller Advantage transmission uses the X-Y Shifter to engage and disengage a gear based on the driver’s selected mode of operation. Gear disengagement is achieved by activating the X-Y Shifter Gear Motor, which controls the fore-and-aft movement of the Shift Finger. Pushing the Shift Finger against one of the Shift Bar Housing Shift Blocks guides the Shift Yoke to disengage the Sliding Clutch from a gear. The position of the X-Y Shift Finger is monitored by the Transmission Electronic Control Unit (TECU) by way of the X-Y Gear Position Sensor and Rail Position Sensor.

Fault Code 71 is set when the X-Y Shift Finger attempts to pull out of gear, but the X-Y Gear Position Sensor indicates that the transmission was unable to disengage that gear. The TECU detected a system failure, but was unable to detect the specific root cause.

Detection:
This fault can only be detected when there are no failures of the TECU, X-Y Gear or Rail Motors, X-Y Position Sensors or Battery Supply voltage. This fault code is set when the system is unable to pull the transmission out of gear.

Conditions to Set Fault Code Active:
FMI 7 – Mechanical System Not Responding: After the first failed attempt to pull to neutral, the system opens the clutch to break torque and attempts to pull to neutral again. If the system is unable to achieve neutral after three consecutive attempts, the fault code sets Active.

Fallback:
FMI 7
• Transmission may not be able to complete a shift to neutral.
• Transmission will attempt to move the Shift Finger to neutral.
• Engine may not crank.
• Gear display may flash current or destination gear.
• Until the fault becomes Inactive, driver may have to shut off engine with transmission in gear.

Conditions to Set Fault Code Inactive:
FMI 7: The system successfully completes a shift into Neutral.

Possible Causes:
FMI 7
1) Vehicle Power Supply
– Poor power or ground supply to TECU
– Bent, spread, corroded or loose terminals
2) Vehicle Batteries
– Internal failure
3) Transmission Harness
– Damaged wiring between the TECU and X-Y Shifter
– Bent, spread, corroded or loose terminals
4) X-Y Shifter
– Worn or damaged X-Y Shifter ball screw, center shaft bushing, or other internal components
– Contamination of X-Y Shifter ball screw due to coolant leak or oil contamination
– Bent, spread, corroded or loose terminals
5) Mechanical Transmission
– Worn or damaged Shift Bar Housing
– Worn or damaged Sliding Clutch slot width
– Worn or damaged Shift Yokes
– Worn or damaged internal transmission components
6) Clutch
– Not properly disengaging (clutch drag)