Changed out rear bulb and system still flashing like bulb is still bad what do i need to do

Sounds more like a bad bulb socket. The bulbs provide a load which causes them to blink slowly. If just one bulb becomes disconnected the load changes and so does the flash rate. I would suspect that you have a bulb that is coming loose in the socket periodically thereby changing the load. Many vehicles us multiple bulbs in the rear...ex. my 04 grand am does the exact same thing. It uses 2 bulbs per tail light. One of the bulb sockets on the drivers side sometimes loses connection and they flash really fast (the other bulb flashes...just 1 of the two quits). In my car i need to replace the tail light assembly.

If the front and rear bulbs flash fast also, replace the hazard switch or you could live with it. As they are working. If one doesn't work, check grounds. I just run a new ground, much easier than cutting open the harness to find the break.

ARE YOU SURE THAT YOU USED THE RIGHT BULBS? IF REARS WORK AND FLASH RAPIDLY THE RELAY IS WORKING. A RAPID FLASH IS CAUSED BY A BAD BULB OR WIRING

ck fuse for rear taillights tis under the dash lower left of steering wheel. or if you still have the manual look in there under fuses.
also look for a bad ground but i doubt that.. if it's both rear out.
fast flashing well here's a chart with all sorts of info.
Problem What To Do Turn signals light, but do not flash Replace the flasher No turn signals light on either side Check the fuse. Replace if defective.
Check the flasher by substitution.
Check for open circuit, short circuit or poor ground. Both turn signals on one side don't work Check for bad bulbs.
Check for bad ground In both housings. One turn signal light on one side doesn't work Check and/or replace bulb.
Check for corrosion in socket. Clean contacts.
Check for poor ground at socket. Turn signal flashes too fast or too slow Check any bulb on the side flashing too fast. A heavy-duty bulb is probably installed In place of a regular bulb
Check the bulb flashing too slow. A standard bulb was probably installed in place of a heavy-duty bulb
Check for loose connections or corrosion at the bulb socket Indicator lights don't work in either direction Check If the turn signals are working
Check the dash indicator lights
Check the flasher by substitution One Indicator light doesn't light On systems with 1 dash indicator:
- See if the lights work on the same side. Often the filaments have been reversed In systems combining stoplights with taillights and turn signals
- Check the flasher by substitution On systems with 2 Indicators:
- Check the bulbs on the same side
- Check the indicator light bulb
- Check the flasher by substitution
hope this helps. may want to print for future reference. :)
hope this helps.

fast flash indicates a bad bulb on that side, or possibly bad socket if new bulb good.

If you have changed the blinkers over to LED lights , you need to put diodes on the wires to stop the fast flash. Honda turn signals Have to grounded to the green ground wires in the harness. You can not ground them to the frame or other wires or the flasher system will not work correctly. Double check that all the wires are connected to the harness correctly (They are color coded). Blue with white band is the same as blue with white stripe. Orange with white band is the same as orange with white stripe. If you have crossed the wires on the front turn signals you may be powering the rear turnsignal with the running light. The running light is the dimmer half of the bulb. The turn signal/flashing light is the brighter side of the bulb. Inspect your wiring carefully.

Obviously your Flasher is defective or one of the Lamps is intermittent. Federal Law requires the Flasher to quit Flashing if a Bulb is Burned Out or the Circuit to either front or rear has an intermittent connection. Next time it Stays on check the Front Bulb for the side you are indicating a turn. If Both Front and Rear Bulbs are lit then replace the flasher. Flashers do wear out!

Fastest Robe

If this is a trailblazer check all the other bulbs in the rear you probably have more than one bad bulb. Chech the bulbs for slight blackaning (flash).

Pull that bulb out and look closely at it, it'll probably have one of the filaments(Tungsten wires) broken and crossed over to the other one causing a short to power and/or the bottom of the bulb has had the 2 lead contacts melt together. In either case the bulb will need to be replaced. If this doesn't fix the problem please let me know so I can look into it further.

Your rear bulb is burnt out if you say the front one is working .. the speed up of flashing means your bulb is bad.. you might have to get in the trunk and unscrrew those hand wing nuts and push that tail light outward to get to the bulbs ... thanks Jerry and holler if you need more.