Eaton Fuller Hybrid Transmission Fault Code 52 – Gear Position Sensor

Fault code for Eaton Hybrid Drive Systems models (MY08) EH-8E306A-U, EH-8E306A-UPG, EH-8E306A-UP, EH-8E306A-CD, EH-8E306A-T, EH-6E606B-CD, (MY09) EH-8E406A-U/P, EH-8E406A-UP, EH-8E406A-UPG, EH-8E406A-CD, EH-8E406A-CDG, EH-8E406A-CDR, EH-8E406A-T, EH-6E706B-CD, EH-6E706B-P and EH-6E706B-UPG. Read below to learn how to test, clear and fix fault code errors for your Freightliner, Mack, Peterbilt, Kenworth, Volvo, and International truck. The Rail Position Sensor is a Hall Effect position sensor that provides feedback on the position of the shift finger. The Transmission Electronic Control Unit (TECU) delivers a constant 5-volt reference to 1 terminal of the Rail Position Sensor. The signal output from sensor provides a regulated voltage signal from 0.5–4.5 volts. The last terminal provides a ground for the Rail Position Sensor to the TECU.

Fault Code 52 – Gear Position Sensor Detection

The following preconditions must be met before the system detects the fault:

  • TECU ignition voltage is greater than 7 volts and less than 16 volts.
  • FMI 3, 4 does not set if the TECU System Battery Voltage Low fault is Active. FMI 2 does not set if FMI 3, 4 is Active.

Note: When troubleshooting an Inactive code refer to the Product Diagnostic Mode (PDM)

Conditions to Set Fault Code Active

  • FMI 2 sets when the transmission controller detects the Rail Sensor voltage is above 4.5 volts or below 0.5 volts for 1 second of longer.
  • FMI 3 sets when the transmission controller detects the Rail Sensor supply voltage is 5% above the expected supply voltage for 1 second or longer.
  • FMI 4 set when the transmission controller detects the Rail Sensor supply voltage is 5% below the expected supply voltage for 1 second or longer.

Fallback When Fault Code 52 is set the following conditions occur:

  • Red “Service” light illuminates and an “F” flashes in the gear display.
  • Fault is stored in TECU memory.
  • If this fault occurs while moving, the transmission remains in the current gear and the clutch opens when the vehicle stops.
  • Operation mode changes to “AutoShift Fallback” mode.

Conditions to Set Fault Code Inactive

Only Inactive faults can be cleared from the Transmission Electronic Control Unit (TECU) or HCM history using ServiceRanger. The TECU automatically clears the faults from history after 200 hours and the HCM automatically clears the faults from history after the fault has been Inactive for 200 hours.

This fault code can be caused by any of the following:

  • FMI 2
    • Transmission Harness
    • Rail Position Sensor
    • TECU
  • FMI 3, 4
    • TECU

Fault Code 52 – Gear Position Sensor Test

Component Identification:

Harness Front View TECU - Vehicle Interface Connector

Harness Front View
(TECU – System Interface Connector)

Gear Position Sensor Pins

Temperature Sensor
(Harness View – Front Side)

NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY08 Systems

NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY09 Systems.

TECU rail position sensor connector location

STEP 1. Check for Active or Inactive fault code status.

  1.  Retrieve Active fault codes and FMIs with ServiceRanger using the 9-Way Diagnostic Connector.
  2. Key off.
  3. Which FMIs are present?
    • If FMI 3 or 4 is listed, replace the Transmission Electronic Control Unit (TECU), then go to Step 5.
    • If FMI 2 is listed, go to Step 2.

STEP 2. Verify continuity of Transmission Harness sensor circuits.

  1. Key off.
  2. Disconnect negative battery cable.
  3. Disconnect the Transmission Harness 38- Way Connector.
  4. Measure resistance between the Transmission Harness 38-Way Connector Pins:
    • 18 and 19
    • 18 and 20
      Note: An auto-ranging digital Volt/Ohm Meter must be used.

      • If Pin 18 and Pin 19 resistance is 100–200 ohms and if Pin 18 and Pin 20 resistance is 5K–7K ohms, go to Step 3.
      • If any of the above conditions are not met, go to Step 4.

STEP 3. Verify continuity of Transmission Harness sensor circuits to ground.

  1.  Measure resistance between Transmission Harness 38- Way Connector Pin 18 to ground.
    • If resistance is 10K ohms or greater, replace the Transmission Electronic Control Unit (TECU) (Only if Fault Code is Active), then go to Step 5.
    • If resistance is less than 10K ohms, go to Step 4.

STEP 4. Verify continuity of Transmission Harness Gear Position Sensor circuit.

  1. Disconnect Transmission Harness from Rail Select Sensor.
  2. Measure resistance between the following Rail Select Sensor Pins:
    • A and C
    • A and B
      Note: An auto-ranging digital Volt/Ohm Meter must be used.

      • If Pin A and Pin C resistance is 5K–7K and if Pin A and Pin B resistance is 100–200 ohms, replace the Transmission Harness, then go to Step 5.
      • If any to the above conditions are not met, replace Electric Shifter, then go to Step 5.

STEP 5. Verify repair.

  1. Key off.
  2.  Reconnect all connectors and negative battery cable.
  3. Key on.
  4. Clear codes, see  Clear Inactive Faults.
  5. Drive the vehicle and attempt to reset the code.
  6. Check for codes, see View Active and Inactive Faults.
    • If no codes, test is complete.
    • If fault Code 52 appears, find error in testing, go to Step 1.
    • If a code other than 52 appears, see Fault Code Index List.

Any transmission part you need we have it! Same day shipping available, worldwide.

NEED FREE SUPPORT FROM ONE OF OUR EXPERTS?

CALL NOW
EMAIL US