How to Use CAT ET 2025C Diagnostic Software – Test ECM Mode

Caterpillar ET 2025C Diagnostic Software includes a powerful feature called Test ECM Mode, which allows a standard ECM to operate temporarily as a Test ECM for advanced diagnostic and troubleshooting purposes.

This guide explains how to activate, monitor, and terminate Test ECM Mode using CAT ET 2025C.

Related Contents:

CAT ET 2025C Software

CAT Comm 3 478-0235

What Is Test ECM Mode?

Test ECM Mode transforms the ECM into a diagnostic test unit, allowing technicians to perform extended testing and troubleshooting without permanently programming the ECM.

Important Note

• Once activated, Test ECM Mode remains active for 24 engine hours
• After 24 engine hours, Test ECM Mode expires automatically unless reactivated
• If longer diagnostics are required, the ECM must be reactivated before the 24-hour limit expires

How to Access Test ECM Mode

To place an ECM into Test ECM Mode:

1. Open CAT ET 2025C
2. Navigate to the Service menu
3. Select ECM Mode

This will open the Test ECM Mode screen.

Test ECM Mode Screen Layout

The Test ECM Mode interface is divided into three main sections:

1. Time Area

• Located at the top of the screen
• Displays the remaining engine hours in Test ECM Mode
• When time remaining drops below 1 hour, the Time Area is enlarged and the following message appears on the Status Line:
  “Less than 1 hour of Test ECM time remaining.”

2. Status Line

• Located in the center of the screen
• Displays the current ECM state:
  • Active
  • Not Active
  • Reactivating
• If testing must continue beyond 24 engine hours, the ECM must be reactivated before expiration

3. Instruction Area

• Located at the bottom of the screen
• Displays:
  • Operating instructions
  • System limitations
  • Usage tips for Test ECM Mode

Available Buttons in Test ECM Mode

Activate / Reactivate

• Select Activate to begin Test ECM Mode
• While Test ECM Mode is active, the button changes to Reactivate
• Reactivate allows Test ECM Mode to continue beyond the default 24 engine-hour limit

Important Restrictions

Test ECM Mode cannot be activated if:

• The ECM has already expired from test mode (engine serial number permanently programmed)
• Engine speed or vehicle speed is detected

Terminate

• Select Terminate to exit Test ECM Mode
• Returns the ECM to standard operating mode

Summary

The CAT ET 2025C Test ECM Mode is an essential diagnostic function that enables temporary ECM testing without permanent programming.