Eaton Fuller Advantage (2017) Fault Code: 43 PID: SPN: 769 FMI: 4 Range Solenoid Valve: Voltage Below Normal or Shorted Low

Overview:
Most 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 by using the main case gearing 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. Auxiliary case gear changes are physically engaged and disengaged to the transmission main case through the Range Synchronizer.

Fault Code 43 indicates an electrical fault within the Range Solenoid Valve circuit.

Detection:
The TECU can detect an open circuit or a short to ground when the Range Solenoid Valve is on. The TECU can detect a short to power when the Range Solenoid Valve is off.

Conditions to Set Fault Code Active:
FMI 4 – Voltage Below Normal or Shorted Low: With the solenoid on, the TECU detects low voltage in the Range Solenoid Valve low side driver circuit for 1 second

Fallback:
All FMIs
• “F” flashes in gear display.
• Service light flashes (if equipped).
• Engine cranks and starts.
• High side coil failure (SID 35/SPN 768).
– If the failure occurs in high range, the transmission shifts through all high range gears and shifts to low range when vehicle speed is appropriate; however, the transmission is then restricted to shifting in all low range gears only.
– If the failure occurs in low range, the transmission shifts through all low range gears but will not shift to high range.
• Low side coil failure (SID 36/SPN 769).
– If the failure occurs in high range, the transmission shifts through all high range gears but will not shift into low range.
– If the failure occurs in low range, the transmission shifts through all low range gears but will not shift to high range.

Conditions to Set Fault Code Inactive:
All FMIs: An electrical short or open circuit is not detected for 2 second

Possible Causes:
FMI 4
1) Transmission Harness
– Wiring shorted to ground
2) Range Solenoid Valve
– Internal short to ground
3) TECU
– Internal short to ground