How to Update the ECM

NOTE:

To ensure the latest program is installed, do an ECM update whenever the ECM is substituted or replaced.
You can not update an ECM with the program it already has. It will only accept a new program.
Before you update the ECM, make sure the vehicle's battery is fully charged.
To prevent ECM damage, do not operate anything electrical (audio system, brakes, A/C, power windows, door locks, etc.) during the update.
If you need to diagnose the Honda interface module (HIM) because the HIM's red (#3) light came on or was flashing during the update, leave the ignition switch in the ON (II) position when you disconnect the HIM from the data link connector (DLC). This will prevent ECM damage.

Turn the ignition switch ON (II). Do not start the engine.
Connect the HDS or the Honda interface module (HIM) to the data link connector (DLC) (A) located under the driver's side of dashboard.

Fig 1: Connecting HDS Or Honda Interface Module
Courtesy of AMERICAN HONDA MOTOR CO., INC.
If the HDS does not have the update function, disconnect the HDS from the vehicle and connect the Honda interface module (HIM).
If the software in the ECM is the latest, disconnect the HDS or the HIM from the DLC, and go back to the procedure that you were doing.
If the software in the ECM is not the latest, do the ECM update procedure as described on the HIM label or in the ECM update system.
Do the ECM idle learn procedure (see ECM IDLE LEARN PROCEDURE ).