Eaton Fuller Hybrid Transmission Fault Code 97 – PTO Engagement

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, International, and heavy-duty truck and equipment.

The PTO is an optional installation on the transmission. The PTO is an electric-over-air unit. The PTO is controlled either by the Hybrid Control Module (HCM) or the Body Controller. Note: This fault is only set if the HCM is directly wired to thePTO. This can be determined by checking the HCM configuration. The “PTO Feedback” will read analog.

HCM-Controlled PTO:

The HCM controlled PTO energizes the electric solenoid and air pressure engages the PTO. The PTO feedback signal is a 12-volt signal. Less than 1 volt indicates the PTO is engaged, and greater than 3 volts indicates the PTO is disengaged.

Body Controller Operated PTO:

The Body Controller operated PTO energizes the electric solenoid and air pressure engages the PTO. When the user selects the ePTO option the Hybrid Control Module (HCM) sends a request to the Body Controller to activate the PTO. When the PTO is engaged, the Body Controller sends back a confirmation message.
Note: When determining which module is controlling the PTO, connect ServiceRanger and view the “Configurations” screen. Under the “Hybrid Control Module” is a listing for PTO Feedback, which is either Analog Controlled (HCM), or J1939 Controlled (Body Controller). The “PTO Engaged” parameter provides the input from the HCM or the Body Controller on the current state of the PTO. This parameter is available in ServiceRanger under the Data Monitor “Hybrid ePTO” list.

Fault Code 97 – PTO Engagement Detection

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

  • Hybrid Control Module (HCM) ignition voltage is greater than 7 volts and less than 16 volts.

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

Conditions to Set Fault Code Active

  • FMI 3 is set when the HCM detects a short to the VBATT in the PTO control circuit.
  • FMI 4 is set when the HCM detects a short to ground in the PTO control circuit.
  • FMI 5 is set when the HCM detects an open in the PTO control circuit.
  • FMI 7 is set when the HCM detects the transmission is in neutral and, if after 8 seconds from requesting PTO mode the PTO engaged signal reads “Disengaged.”
  • FMI 14 is set when the ePTO option on the Push Button Shift Control is selected and the HCM detects the transmission is not in neutral based on output shaft speed.

Fallback When Fault Code 97 is set the following conditions occur:

  • Fault is stored in HCM memory.
  • If the PTO is engaged and the fault occurs, the PTO remains engaged until the ePTO request changes, or the air pressure drops below a
    set limit.
  • If the PTO is not engaged the ePTO light flashes on the Push Button Shift Console.

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 7:
    • PTO Air Solenoid
    • Low air pressure
    • PTO control circuit wires
    • PTO
    • PTO feedback circuit
    • PTO Ball Switch

Fault Code 97 – PTO Engagement Test

Component Identification:

Hybrid Control Module

1. Hybrid Control Module (HCM)
2. Nut (3)
3. 38-Way System Connector Plug-in
4. 38-Way Vehicle Connector Plug-in
5. Mounting Plate

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.

STEP 1.Verify FMIs present.

  1.  Retrieve Active fault codes and FMIs with ServiceRanger using the 9-Way Diagnostic Connector or manually.
  2. Key off.
  3. Which FMIs are present?
    • If Fault Code 97 FMI 3 is listed, go to Step 2.
    • If Fault Code 97 FMI 4 or 5 are listed, go to Step 3.
    • If Fault Code 97 FMI 7 is listed, go to Step 6.
    • If Fault Code 97 FMI 14 is listed, contact Eaton at 1-800-826-HELP (4357).

STEP 2. Verify voltage output at HCM 38-Way.

  1. Key off.
  2. Disconnect the negative battery cable.
  3. Disconnect the HCM Harness 38-Way Connector.
  4. Key on.
  5.  Measure the voltage from Pin 34 to ground on the HCM Harness 38-Way Connector:
    • If voltage from Pin 34 to ground is 0 volts, replace the Hybrid Control Module (HCM)
      (only if fault code is Active), then go to Step 8.
    • If voltage from Pin 34 to ground is 11–13 volts, repair the Hybrid System Harness for a short to battery, then go to Step 8.

STEP 3. Verify continuity of PTO solenoid circuit.

  1. Key off.
  2. Disconnect the negative battery cable.
  3. Disconnect the HCM Harness 38-way connector.
  4. Measure the resistance between the HCM Harness 38- Way Connector and the following pins:
    • Pin 34 to Pin 6
    • Pin 34 to ground
      • If resistance between Pin 34 and Pin 6 is 0–0.3 ohms and resistance between Pin 34 and ground is 10K ohms or greater, replace the Hybrid Control Module (HCM) (only if fault code is active). Go to Step 8.
      • If resistance is out of range, go to Step 4.

STEP 4. Measure resistance of the HCM Harness to ground.

  1. Key off.
  2. Disconnect the PTO 2-Way Connector at the PTO.
  3. Measure the resistance between the PTO 2-Way Connector at the following pins:
    • Pin A to Pin B
    • Pin A to ground
      • If resistance between Pin A and Pin B is 0–0.3 ohms and resistance between Pin A and ground is 10K ohms or greater, repair the Hybrid System Harness for an open or short to ground, then go to Step 8.
      • If resistance is outside of range, replace the PTO Switch, then go to Step 8.

STEP 5. Check for Active FMIs

  1. If Fault Code 97 FMI 3, 4, or 5 are Active:
    1. Go to Step 1.

STEP 6. Measure voltage at the Signal Wire to ground.

  1. Disconnect the PTO single signal wire at the PTO.
  2. Key on.
  3.  Measure the voltage from the PTO Signal Wire Connector to ground:
    • If the voltage is 12 volts at key on, problem is with the faulty PTO engagement signal switch in the PTO. Contact your OEM for repair procedures.
    • If the voltage is less than 1 volt at key on, go to Step 6.

STEP 7. Verify continuity on PTO signal wire.

  1. Key off.
  2. Disconnect the negative battery cable.
  3. Disconnect the HCM Harness 38-Way Connector.
  4. Measure the resistance from the HCM Harness 38- Way Connector Pin 18 to the opposite PTO end of the Signal Wire.
    • If the resistance from Pin 18 to the PTO end of the signal wire is 0–0.3 ohms, replace the Hybrid Control Module (HCM), then go to Step 8.
    • If the resistance is outside of range, repair the open in the PTO signal wire from the HCM to the PTO, then go to Step 8.

STEP 8. Verify repair.

  1. Key off.
  2. Reconnect all connectors and the 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 97 appears, find error in testing, go to Step 1.
    • If a code other than 97 appears, see Fault Code Index List.

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