When the 150-450mm is mounted the camera will not shift to AF on the LCD screen. I have checked all switches and settings both on the lens and the camera. My other two lenses continue to work fine. It appears to be an electrical problem inside the lens, has anybody experienced this problem and is there something I might have missed before I package it up and send it in for repair?

[aslyfox]

no such problems with mine

have you reviewed these ?

HD Pentax-D FA 150-450mm F4.5-5.6 (APS-C)
Introduction
The long-awaited HD Pentax-D FA 150-450mm F4.5-5.6 ED DC AW telephoto zoom made its debut in early May, 2015 as the first of an upcoming series of Pentax full frame lenses. It was originally announced at CP+ 2015 in Tokyo alongside the Pentax full frame DSLR, which is scheduled for release in late 2015


Read more at: HD Pentax-D FA 150-450mm F4.5-5.6 Review - Introduction | PentaxForums.com Reviews

HD Pentax-D FA 150-450mm F4.5-5.6
Introduction
Back in June 2016, we presented our first review of the HD Pentax-D FA 150-450mm F4.5-5.6 ED DC AW, which was the first member of the new lineup of full frame zoom lenses from Pentax. At the time, the review had been performed with a K-3 camera body as the full-frame K-1 had been announced but not yet released. Now that the K-1 has been out for some time and more users have access to it, it is time to revisit our review, this time testing the lens wih a full frame sensor.


Read more at: HD Pentax-D FA 150-450mm F4.5-5.6 Review - Introduction | PentaxForums.com Reviews

what camera body ?

[UncleVanya]

"will not shift to AF on the LCD screen" is a little confusing. Since there are multiple LCD's on the K-1 which one is showing this? (I ask as a non-K-1 owner). I assume you are not seeing "F--" and you are able to set an aperture?

[jatrax]

I have checked all switches and settings both on the lens and the camera.

Make sure the lens is not in MF mode. Move that switch back and forth and watch the LCD to see if anything changes. I know you checked but that is the obvious answer. If that's not it and the camera is also in AF mode then try cleaning the contacts with a microfiber cloth.

If that doesn't work I'm out of ideas, may need a service call.

[Mikesul]

When the 150-450mm is mounted the camera will not shift to AF on the LCD screen. I have checked all switches and settings both on the lens and the camera. My other two lenses continue to work fine. It appears to be an electrical problem inside the lens, has anybody experienced this problem and is there something I might have missed before I package it up and send it in for repair?

Which camera are you using? Do you mean the mode dial will not turn to AF or that when you turn it to af it does not show as AF on the rear lcd or top lcd?