I think i have three, ive got one in the rear and two up front , the side marker next to the headlight and the one below the headlight and the one in the rear, what one would i be missing?

 

Should also have 2 in the rear as well

 

Have you replaced the flasher unit? It sounds like it is going bad and will soon stop working one of these days soon.

 

Yes you are correct, both the upper and middle lights in the rear blink, didnt catch that the first time, so that works to and i also switched that bulb side to side, still have the issue.

Will try the flasher unit and report back tomorrow

 

Back to basics; If the flasher is normal style, the length of time the bulbs are "On" is determined by the current (this current heats an element in the flasher). The length of time they are "Off" is how long that element takes to cool back down. A "short" circuit to ground, will speed up the flashing a bit and the lights won't be "on" as long.

In general we say that a fast flash means a short to ground, or a high current. This often means the light close to the short will be dim also. It's unusual for a BULB to draw more current and cause this. Bulbs tend to either "work" or go "out".

The 4 way flasher button has a very high number of connectors and circuits passing thru it AND is in a very bad location. Unlike previous decades of GM vehicles with reliable 4way switches, our EMERGENCY flasher switch is mounted so that dust settles DOWN into the switch. Dust, Dirt, Soft Drinks, anything is pulled by gravity into the switch and causes them to go bad. Once they start going bad, they can heat up, plastic can melt, and all kinds of crazy stuff can start happening.

If I were you, I'd consider the 4 Way switch.

 

That is not the case in the 2nd gen trucks. True for older trucks, but not the one being talked about here. The old bi-metal flashers haven't been used for quite some time. The flasher has a current sensing circuit built into it. High load (all bulbs lit) = low flash rate. Low load (bulb out or lower current bulbs) = high flash rate. This is why most people have to run ballast resistors when switching over to LED bulbs. The bulbs do not have anywhere near the current draw of the original filament type bulb and a hyper flash results. This hyper flash is GM's way of telling you a bulb is out.

If all of the bulbs work properly and you've double/triple checked them ALL, then the flasher is the next logical step.

 

Well i ended up taking it to a shop, i didnt want to keep throwing parts at it, they changed the flasher unit, and all is well thanks for all the help

 

And that's why Kyle's the guru.