Eaton Fuller Advantage (2017) Fault Code: 51 PID: SPN: 60 FMI: 4 Rail Position Sensor: Voltage Below Normal or Shorted Low

Overview:
The Fuller Advantage X-Y Shifter is equipped with a Rail Position Sensor. The X-Y Rail Position Sensor reports lateral movement of the Shift Finger to the Transmission Electronic Control Unit (TECU) as a voltage signal. The X-Y Rail Position Sensor is connected to the TECU via the Transmission Harness.

The TECU performs continuous diagnostics on the circuit to detect a shorted circuit, open circuit or incorrect position reading. Fault Code 51 is set when the TECU has detected either an electrical failure of the X-Y Rail Position Sensor circuit or a mechanical failure within the X-Y Shifter.

Detection:
The TECU monitors both the 5-volt X-Y Rail Position Sensor supply and the return voltage signal from the X-Y Rail Position Sensor. If the system detects that either the supply voltage or return voltage is out of range, the fault code is set Active.

Conditions to Set Fault Code Active:
FMI 4 – Voltage Below Normal or Shorted Low: TECU detects the X-Y Rail Position Sensor supply voltage is below 4.75 volts for 1 second or longer

Fallback:
All FMIs
• “F” flashes in gear display.
• Service light flashes (if equipped).
• Transmission remains in current gear.
• Until the fault becomes Inactive, driver may have to shut off engine with transmission in gear

Conditions to Set Fault Code Inactive:
FMI 3, 4: Supply voltage stays within the 4.75–5.25 volt range for 1 second

Possible Causes:
FMI 2, 4 or 10
1) Transmission Harness
– Bent, spread, corroded or loose terminals
– Wiring shorted to ground, shorted to power or open
2) X-Y Shifter
– Bent, spread, corroded or loose terminals
– Wiring shorted to ground, shorted to power or open
– Rail Position Sensor damaged
3) TECU
– Internal failure