Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
How to Update the PCM
2005 Honda Accord L4-2.4LSECTION How to Update the PCM
How to Update the PCM
Special Tools Required
Honda diagnostic system (HDS)
Honda Interface Module (HIM)
HDS Pocket Tester
NOTE:
^ Use this procedure when you need to update the PCM during troubleshooting procedures.
^ 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, moonroof, and door locks, during the update.
^ 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.
^ 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. Turn the ignition switch ON (II). Do not start the engine.
2. Connect the HDS or the Honda interface module (HIM) to the DLC (A) located under the left end of the dash.
3. Make sure the HDS communicates with the PCM. If it doesn't, go to the DLC circuit troubleshooting.
For '06-07 models: If you are returning from the DLC circuit troubleshooting, skip steps 4 and 5, then clean the throttle body after updating the PCM.
4. For '06-07 models: Select the INSPECTION MENU with the HDS.
5. For '06-07 models: Select the ETCS TEST, then select the TP Position Check, and follow the screen prompts with the HDS.
NOTE: If the TP POSITION CHECK indicates FAILED, continue this procedure.
5. If the HDS does not have the update function, disconnect the HDS from the vehicle and connect the Honda interface module (HIM).
6. Exit the HDS diagnostic system, then select the update mode, and follow the screen prompts to update the PCM.
7. 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, follow the instructions on the screen. If prompted to choose the PGM-FI system or the A/T system, make sure you update both.
NOTE: If the PCM update system requires you to cool the PCM, follow what is shown in the screen. If you run into a problem (programming takes over 15 minutes, status bar goes over 100%, D or immobilizer indicator flashes, HDS tablet freezes, etc.) during the update procedure, follow these steps to minimize the chance of damaging the PCM:
^ Leave the ignition switch in the "ON (II)" position.
^ Connect a jumper battery (do not connect a battery charger).
^ Shut down the HDS.
^ Disconnect the HDS from the DLC.
^ Reboot the HDS.
^ Reconnect the HDS to the DLC, and try the update procedure again.
8. For '06-07 models: If the TP POSITION CHECK failed in step 6, clean the throttle body.
9. Do the PCM idle learn procedure.
10. Do the CKP learn procedure.
Special Tools Required
Honda diagnostic system (HDS)
Honda Interface Module (HIM)
HDS Pocket Tester
NOTE:
^ Use this procedure when you need to update the PCM during troubleshooting procedures.
^ 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, moonroof, and door locks, during the update.
^ 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.
^ 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. Turn the ignition switch ON (II). Do not start the engine.
2. Connect the HDS or the Honda interface module (HIM) to the DLC (A) located under the left end of the dash.
3. Make sure the HDS communicates with the PCM. If it doesn't, go to the DLC circuit troubleshooting.
For '06-07 models: If you are returning from the DLC circuit troubleshooting, skip steps 4 and 5, then clean the throttle body after updating the PCM.
4. For '06-07 models: Select the INSPECTION MENU with the HDS.
5. For '06-07 models: Select the ETCS TEST, then select the TP Position Check, and follow the screen prompts with the HDS.
NOTE: If the TP POSITION CHECK indicates FAILED, continue this procedure.
5. If the HDS does not have the update function, disconnect the HDS from the vehicle and connect the Honda interface module (HIM).
6. Exit the HDS diagnostic system, then select the update mode, and follow the screen prompts to update the PCM.
7. 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, follow the instructions on the screen. If prompted to choose the PGM-FI system or the A/T system, make sure you update both.
NOTE: If the PCM update system requires you to cool the PCM, follow what is shown in the screen. If you run into a problem (programming takes over 15 minutes, status bar goes over 100%, D or immobilizer indicator flashes, HDS tablet freezes, etc.) during the update procedure, follow these steps to minimize the chance of damaging the PCM:
^ Leave the ignition switch in the "ON (II)" position.
^ Connect a jumper battery (do not connect a battery charger).
^ Shut down the HDS.
^ Disconnect the HDS from the DLC.
^ Reboot the HDS.
^ Reconnect the HDS to the DLC, and try the update procedure again.
8. For '06-07 models: If the TP POSITION CHECK failed in step 6, clean the throttle body.
9. Do the PCM idle learn procedure.
10. Do the CKP learn procedure.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.