My tech was working on Cat C3500 s/n AT81FG0264. The dash indicated a fault code which the tech has made the repair for. he then tried to clear the code on the dash by doing the following: turn key on for 3 seconds, pump accelerator 5X, let off accelerator for 10 seconds, then hold accelerator down for 10. This has not cleared the dash and the code is still flashing. Anyone have any suggestions.....thanks.