Honda PGM Tester or HDS Clear Command The inside ECM/PCM stores various specific data to correct the system even when there is no electrical power such as the battery negative terminal or No. 8 FI ECU (ECM/PCM) (15 A) fuse are disconnected. But stored data based on failure parts should be cleared by using the ‘‘CLEAR COMMAND'' of the HDS, if parts are replaced.
The HDS has three kings of clear command to meet the purpose. They are DTC clear, ECM/PCM reset and CKP pattern clear. DTC clear command erases all stored DTC codes and Freeze Data. This must be done with the HDS after reproducing DTC during troubleshooting. The ECM/PCM reset command erases all stored DTC codes, Freeze Data and all specific data to correct the system except CKP pattern. If the CKP pattern data inside of ECM/PCM was cleared, you must do the CKP pattern learn procedure by test drive. CKP pattern clear command erase only CKP pattern data. This command is for the repair of the misfire or CKP sensor.