Eaton Fuller Advantage (2017) Fault Code: 41 PID: SPN: 769 FMI: 7 Range Failed to Engage: Mechanical System Not Responding

Overview:
Most Heavy-Duty Fuller Advantage Transmission models are equipped with a 2-speed range system in the auxiliary case. The ability to select an auxiliary range gear independently from a main case gear allows the transmission twice the number of overall gear ratios. Main case gearing can be used once in auxiliary low range and again in auxiliary high range. The range system is equipped with a Range Solenoid Valve. The Range Solenoid Valve is an electric-over-air solenoid that is controlled by the Transmission Electronic Control Unit (TECU), replacing the Shift Knob-Slave Valve system found on Eaton Fuller manual transmissions. During operation, the solenoid directs air pressure to either port in the Range Cylinder based on the need to activate the auxiliary low range or high range gearing. The applied air pressure directs the fore-and-aft movement of the Range Piston within the Range Cylinder, facilitating the mechanical engagement of the Range Synchronizer into either low or high range. Fault Code 41 indicates the transmission is unable to complete a range shift.

Detection:
When toggling the Range Solenoid Valve, the TECU verifies the new range position by calculating the overall transmission gear ratio, using the Main Shaft and Output Shaft Speed Sensor signals. If the calculated ratio does not match the expected ratio for the new range position, the auxiliary case gearing did not change as expected and the TECU sets the fault code Active. The TECU detected a range system failure, but was unable to detect the specific root cause.

Conditions to Set Fault Code Active:
FMI 7 – Mechanical System Not Responding: Transmission is either stuck in its current range position or it cannot engage the desired range position after five consecutive attempts.

Fallback:
FMI 7
• Transmission remains in the range where the failure occurred.
• Transmission may attempt to shift into low range when the vehicle comes to a stop.
• Until the fault becomes Inactive, driver may have to shut off engine with transmission in gear.

Conditions to Set Fault Code Inactive:
FMI 7: Transmission successfully attains the requested range for 2 seconds.

Possible Causes:
FMI 7
1) Vehicle Air System
– Low vehicle air pressure
– Contamination in air supply
– Air leaks
– Filter-Regulator failure
2) Range Solenoid Valve
– Mechanical failure
3) Mechanical Transmission
– Range Synchronizer failure
– Range Cylinder, Piston or Yoke wear or damage
– Range Cover Gasket failure
– Tone Wheel damage
– Failed auxiliary case components
4) Main Shaft Speed Sensor
– Internal failure
5) Output Shaft Sensor
– Internal failure