In the 1999 to 2004 honda odyssey there are indications that your alternator is starting to go bad. There are dash lights that will come on to let you know something is going on under the hood. In most cases the lights that will come on are the battery light, brake light, and the door indicator lights. These lights will come on altogether at the same time. Sometimes they will flicker if the alternator hasn’t completely died, but is on its way to complete failure. If the lights come on and stay on, that could mean it has gone to a better place. There are brushes inside the alternator that just get a little hung up, and In some cases the alternator can be brought back to life for a short time. There are ways to free up the brushes inside the casing. You may be able to give it a knock with a hammer while its running to jump start its heart to give it just enough life to get you to the auto parts store for an alternator transplant. Check to see if the dash lights go away after you gave it the knock. If they did, all that means is you now may have enough time to take it somewhere to get it taken care of, so don’t wait too long. One thing you should do when buying a new alternator is to have them check and TEST the new one before you leave the store because it is pretty common to get a bad alternator, and when you do you may have to do the replacement job twice if that happens, Not Fun! Remember even know its new get it tested before you leave the auto parts store. This is from first hand experience.