PCM Updating and Substitution for Testing Special Tools Required Honda Interface Module (HIM) EQS05A35570 Use one of these procedures when you have to substitute a known-good PCM in a troubleshooting procedure. Update the PCM only if the PCM does not already have the latest software loaded.
NOTE: Do not turn the ignition switch OFF while updating the PCM. If you turn the ignition switch OFF before completion, the PCM can be damaged.
How to Update the PCM
NOTE:

- To ensure the latest program is installed, update a PCM whenever the PCM is substituted or replaced.
- You cannot update a PCM with the program it already has. It will only accept a new program.
- Before you update the PCM, make sure the vehicle's battery is fully charged.
- To prevent PCM damage, do not operate any electrical system; audio system, brakes, air conditioning, power windows, sunroof, and door locks, 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 PCM damage.

1. Connect the HDS to the DLC (A) located under the driver's side of the dash.
   NOTE: The illustration shows LHD model; RHD model is symmetrical.

1. Turn the ignition switch ON (II).

1. Select PGM-FI, then the INSPECTION MENU with the HDS.

1. Do the TP POSITION CHECK in the ETCS TEST.

1. If the HDS does not have the update function, disconnect the HDS from the vehicle and connect the Honda interface module (HIM).

1. If the software in the PCM 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 PCM is not the latest, do the PCM update procedure as described on the HIM label or in the PCM update system.

1. Do the PCM idle learn procedure.

1. Do the CKP pattern clear/pattern learn procedure.

How to Substitute the PCM

1. Connect the HDS to the DLC (A) located under the driver's side of the dash.

1. Turn the ignition switch ON (II).

1. Select PGM-FI, then the INSPECTION MENU with the HDS.

1. Do the TP POSITION CHECK in the ECTS TEST.

1. Turn the ignition switch OFF.

1. Jump the SCS line with the HDS.

1. Remove the PCM, then install a known-good PCM.

1. Open the SCS line with the HDS.

1. Turn the ignition switch ON (II).

1. Select PGM-FI, then the REPLACE ECM/PCM, WRITE DATA.

1. Rewrite the immobilizer code with the PCM replacement procedure in the HDS; it allows you to start the engine.

1. Reset the PCM with the HDS.

1. Do the PCM idle learn procedure.

1. Do the CKP pattern clear/pattern learn procedure.