Eaton Fuller Transmission Hybrid Light & Gear Display Descriptions

All Eaton Fuller hybrid systems use a combination of 3 lights to indicate failures of different operating systems and the ability of the vehicle to drive. These lights include the red “Service” light, amber “Check Hybrid” light, and the red “Stop Hybrid” light. Read Below for Eaton Fuller transmission hybrid light & gear display descriptions.

Red “Service” Light

• Light is located on the Push Button Shift Control and reads “Service”.
• Light is turned on and off by the Transmission Electronic Control Unit (TECU) for automated transmissions faults over the High Integrity Link (HIL).
• Light also comes on momentarily at key on as part of the TECU self-test.

Amber “Check Hybrid” Light

• Light is located near the middle of the dash. It is amber and reads “Check Hybrid.”
• Light is turned on and off indirectly by the Hybrid Control Module (HCM) and directly by the Body Controller over J1939.
• Light is turned on when a hybrid system fault is Active.
• When the amber light is on, the vehicle can still be driven; however, the vehicle may operate without hybrid electric assist.

Red “Stop Hybrid” Light

• Light is located near the middle of the dash. The light is red and reads “Stop Hybrid”.
• Light is turned on and off indirectly by the HCM and directly by the Body Controller over J1939.
• Light is turned on when a hybrid system fault is Active.
• When the light is on, vehicle should not be driven. Transport the vehicle to the OEM truck dealership.

Blinking Amber “Check Hybrid” Light

The majority of vehicles have a red Stop Switch on the front of the Power Electronics Carrier (PEC). If this switch is pushed in, the amber “Check Hybrid” light will blink.

• To reset, pull switch out and turn key off for 2 minutes. Continue to the diagnostic test for the fault that is currently Active.
• If the light remains on, go to “Hybrid Diagnostic Procedure” and start with step 3 “Retrieve Active Faults with ServiceRanger.”
• There should be an Active Fault Code 76 FMI 4, or Fault Code 116, FMI 10.

“ST” in Gear Display

A “ST” in the gear display indicates a driver-triggered snapshot was recorded. Snapshot is a diagnostic tool that is used to capture specific data at the time a fault occurs. It is triggered through two different means listed below:

• Fault code triggered – Specific faults will trigger the HCM or TECU to capture a snapshot file for later retrieval. This method will not display an “ST” in the gear display.
• Driver triggered – If the driver chooses to capture a snapshot of an event, he needs to decide if he wants TECU or HCM data. To capture a TECU snapshot select, Low and the Up button twice. To capture a HCM snapshot select, Drive or Low and the Up button and the Down button.

“PD” in Gear Display

A “PD” in the gear display indicates the TECU and HCM are in a special diagnostic mode called Product Diagnostic Mode (PDM).For more details on the mode and its operation, see “Product Diagnostic Mode (PDM)”

“CA” in Gear Display

“CA” in gear display indicates HCM is detecting a clutch abuse situation.

• If the HCM detects a clutch abuse situation it will first tone the Push Button Shift Control and flash a “CA” in the gear display.
• If the clutch abuse situation continues, the hybrid system will allow only an electric launch in addition to continuing the tone and the “CA.”
• If the clutch abuse continues while driving, the hybrid system will open the clutch when vehicle speed is below 5mph and allow the clutch to cool.

“OS” in Gear Display

“OS” in the gear display indicates the HCM is detecting a motor overspeed situation. The vehicle will upshift in Drive and Low automatically; however, if the vehicle is in manual mode, close to motor overspeed and the driver fails to upshift, the vehicle will:

• Display an “OS” indicating the driver needs to press the service brake pedal to slow the vehicle; or,
• The HCM will either upshift the vehicle or reduce torque to prevent the motor from going overspeed.

“F” in Gear Display

“F” in the gear display indicates the TECU has detected an Active fault. This fault can be accessed with ServiceRanger. See Fault Code Isolation Procedure Index.

Dash”-” in Gear Display

A “-” in the gear display indicates the transmission is stuck in gear. See Symptom-Driven Diagnostics Index.

Stars “**” in Gear Display

Two stars “**” in the gear display indicates the gear display has power, but no communication on the data link. See
Symptom-Driven Diagnostics Index.

Two Dashes “- -” in Gear Display

Two dashes “- -” in the gear display indicates the gear display has power, and there is no communication present on the data link, or the TECU isn’t communicating with the display. See Symptom-Driven Diagnostics Index.

Blank Gear Display

A blank gear display indicates the display has lost power, or the TECU isn’t communicating with the gear display. See Symptom-Driven Diagnostics Index.