EOS 5D Mark IV is have a Communication error with my 24-70 and won’t focus

[AshelyA02]

I have a canon 5D Mark Iv. I got an error 01: “Communication between lens and camera is faulty” with my 24-70 mm lens. I read to carefully clean the gold contacts with a lens cloth. I did and tried it again and got the same error. I tried a different lens and it connected fine, but on live view it only worked on MF. When I tried AF mode, it wouldn’t focus using the back button or the shutter button. I doubled checked all of my settings and everything is set where is should be, so I’m wondering if it’s both my lens and camera?

[p4pictures]

If you have another lens, or can borrow one then try that. If the other lens works with no error then it's your 24-70mm that is at fault. If the other lens you try gives the same error as your 24-70mm then it is possibly the body.

[AshelyA02]

Thank you for the response. The 24-70 mm lens had the Err 01. When I tried a different lens, it connected okay, but my camera wouldn’t focus at all on live viewing with any of my lenses.

[p4pictures]

Does the camera focus with the different lens when not using Live View? If so then it could be the Live View settings that are the cause. 

Check to see if you have continuous AF enabled, the constantly focuses the lens when in Live View even if no button is pressed. Also check the AF method form the Live View menus and check if you have disabled the shutter from activating AF with custom controls.