Canon 580EX Flash will not fire. Being shot on a Canon 5D Mark III.

[PhotoExpression]

The light  does not start out green and stays red on the 580EX Flash. It doesn't even go into a sleep mode when not activated for a length of time.  Fresh batteries does not make a difference.  It will allow me to change settings but it won't fire. The infra-red displays it's test light but the flash will not discharge even when it demands it.  It is not on slave or wireless settings.  Nothing makes the flash go off, even the test flash.

[simplyouphoto]

I have the 600 EX-RT flash. Everything I've read says it's a focus assist beam or that I'm pressing the depth of field preview (I own the Mark II 5d. It rapid fires & then the viewfinder goes a bit darker & the shutter button won't work. 

[Samiamphoto1569]

The same thing is happening to me. I've tried everything. Did you find the cause or do I need to send it in?

[TCampbell]

This is an old thread but...

Please GENTLY wiggle the flash when mounted and locked into the hot shoe.  Does it move?

There is an issue that can happen if the plate on the flash shoe becomes loose.  The flash will be slightly wobbly but moreover the pins that communicate with the camera will not all make contact and this means the flash wont know to fire, E-TTL wont work, the flash wont know if the camera is sleeping or awake, etc.

The safest fix is to send the flash to Canon for service.  

There are articles and instructions available on the Internet to fix the problem yourself -- which involves removing the four screws that hold the foot onto the flash, and then tightening the screws that hold the plate to the foot -- then reassembling.  I don't necessarily recommend fixing it yourself (especially if you're not comfortable and experienced doing such things).  

Remember:  If you break it, you get to keep both halves.  Sending it Canon to have them fix it is always the safer option.

[Samiamphoto1569]

thank you....

i have a certified canon camera  fixer here in miami.

i will drop it off to them first.