So I can't figure this out but both my turn signals are blinking fast and the hazards blink normal. I have checked all the bulbs and they work. They are all stock bulbs no leds. Is the side marker light in the headlight supposed to blink or no. Because other then that I don't know why it would do this. This weekend I'm going to go though all the fuses and check because I also have a drain on the battery, so maybe something is messed up with the blinkers and I will find it.

 

The flasher? Different flasher for the hazards.

 

Sorry forgot to mention its a 2008 f250 and from what I read it is computer controlled not old school flashers. That was my first thought.

 

flasher could be possibly going bad, not to sure about the 2008 F250 but most are the old load based type, and are up under the dash just under the radio area for the 99 - 03 (possibly a few others after)

 

Well thats interesting...

 

are ALL your bulbs working [parking/taillights/hi-beam/low beam/driving lights]?

this could be Ford's way of getting you to check.

If you have autogenuity with the ford-enhanced pack, it might give you some idea's on what's up [on my '04 GM, it came up with history codes for my burned out bulbs].

 

The truck is a basic XL so I don't think it has a monitor system for the bulbs. I will double check again on if bulbs are working but I'm positive they are. Does anyone know if the side marker bulbs in the headlight housing are supposed to blink? Mine don't and I just want to make sure its not because of those?

 

On the 08+ Super Duties, the flash rate is controlled by software in the Smart Junction Box (SJB). There is no longer a flasher relay. The factory default setting for the SJB is to monitor for a bulb outage and to double the flash rate if an outage is detected.

Go check and see if the TURN SIGNALS, both front and rear, are working on both sides and front and rear of the truck. Do NOT use the hazards for this simple check. Also, check the signal lamps in the mirrors, if equipped.

Your Ford dealer can re-program the SJB using their IDS to turn off the bulb monitor, if necessary.

 

is it possibly a ground wire?
I have the same problem but I cant find where the tail lights are grounded

 

You need to fully identify what you're working on when you ask questions. Assuming we know or can guess (or are inclined to go figure it out from past posts) is assuming that we're interested enough to do that. Just put the information in your post.

Are you having a problem with "tail" lights, properly called either parking or running lamps or are you have in a problem with the stop/turn signals? The grounds are the same for both in the back, but the rest of their respective circuits are separate.

 

sorry 2008 F250. rear stop lights are not working. rear running lights not working. Rapid turn signal blinking but only when the headlights are turned on.

 

So quick update. I bought towing mirrors with turn signals and was surprised to see the wiring was there. All my turn signals are working including mirrors but they are still blinking fast. So I took my truck to the Ford dealer to have them reprogram the smart box thing. They called me and said they need both key fobs to reprogram it because the box and that it is saying I have third row seats. I'm so confused because my truck is an basic XL crew cab and didn't come with key fobs that I know of. It does have power locks but I really don't want to spend a few hundred dollars on fobs I don't even want just to fix this. Anyone know if this is true?

 

So another update I went in an actually talked to the guy who worked on my truck. Apparently the smart junction box that is installed in my truck is the wrong one and it has to reprogrammed to an f250 which makes sense now. However does anyone know if I actually need key fobs to have them reprogram the truck? I am about to move east coast to west coast next week so I don't want to blow the money on new fobs but if I have to I will when I get to Washington. I can't stand my blinker flashing so fast. Just got to find a trust worthy dealer out there lol.

 

My 2016 F150 had sudden onset of both blinkers blinking fast, and neither rear signal light worked. Since they happened at the same time, your suggestion of checking the ground wire sounded right, and that is precisely what my problem was.
My truck's ground wire is located in the rear, attached with a screw to the frame rail on the passenger side very near the rear bumper and near the spare tire.
It turns out my dog chewed that wire. It was an easy fix with a piece of wire and appropriate connectors.

 

2008 F250. Passenger side turn signal started flashing very quick while driver side flashed normal. Discovered rear passenger light was burned out. Replaced both rear lights with LED bulbs. Emergency lights flash normal but now both left and right turn signals flash very fast. Any ideas?