try this, have your anti theft code card ready, vehicle full stop, engine not running...then at passenger's side under dash fuse box, locate the #13 fuse, theres a diagram on the fuse box itself, remove it for 10 seconds then return it from where you pulled it. afterwards, input code at radio then drive the vehicle the usual. if it still blinks, go to a trusted mech to have it scanned cause the powertrain control module senses some abnormality thats why it blinks... maybe temperature sensor or pressure switches of the transmission....My 2003 Honda Pilot has a flashing "D"... it started off occasionally and has been happening more frequently. Its annoying, but is it dangerous? Does anyone know what causes this? Our local dealer in not so helpful. Thks.
sometimes...again, sometimes a transmission fluid change does the trick. year today is 2007 your pilot model 2003, every 3yrs ,as per manual, change transmission fluid along w/ brake fluid.
keep us posted, goodluck and good day!