ECM/PCM Updating and Substitution for Testing Special Tools Required Honda interface module (HIM) EQS05A35570 Use this procedure when you have to substitute a known-good ECM/PCM in a troubleshooting procedure. Update the ECM/PCM only if the ECM/PCM does not have the latest software loaded.
NOTE:

- Do not turn the ignition switch OFF while updating the ECM/PCM. If you turn the ignition switch OFF before completion, the ECM/PCM can be damaged.
- To ensure the latest program is installed, do an ECM/PCM update whenever the ECM/PCM is substituted or replaced.
- You cannot update an ECM/PCM with the program it already has. It will only accept a new program.
- Before you update the ECM/PCM, make sure the vehicle's battery is fully charged.
- To prevent ECM/PCM damage, do not operate anything electrical (audio system, brakes, A/C, power windows, sunroof, 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/PCM damage.

1. Turn the ignition switch ON (II). Do not start the engine.

1. Connect the HDS or the Honda interface module (HIM) to the data link connector (DLC) (A) located under the driver's side of the dashboard.

1. Do the ECM/PCM update procedure as described on the HIM label and in the ECM/PCM update system.

1. Do the ECM/PCM idle learn procedure.

1. Clear the CKP pattern with the HDS while the engine stopped.