2005 Envoy will not start

My 2005 Envoy XUV 6 cylinder, 63000 miles periodically will simply not crank. The problem is random, intermittent but maddening.
For approximately the last month the car cranks in the morning 100% of the time. Occasionally, I will leave the office for lunch and the car will not crank. The switch turns, the gauges light up/the needles jump but nothing–no sound, the engine does not turn over–complete silence. Sometimes, I will turn the key and the car starts the very next time, sometimes it is 30 minutes, sometimes an hour. There are no codes registering. It 's been towed twice to the shop. Once there it cranks every time , all the time. They have kept it for days and can find nothing wrong. The last maintenance was replacing a cam shaft sensor. The battery is strong the connection are sound. Since the car cranks at the shop, they tell me they can not determine if the switch or starter are bad. I can find no pattern to this. I turn the key and there is complete silence or I turn the key and it cranks immediately. Please help

Assuming that it is an automatic, the next time it happens, put it in neutral and then try to start it. If that works either keep doing it or tell the shop about it & they’ll put in a new neutral safety switch or shift lever position sensor (whichever).

Thanks. We have checked this and it is not the neutral safety of shift level sensor. It is an auto.

Bring a rubber mallet with you and whack the starter with it next time it doesn’t start even when in neutral. If the starter is buried further down, also bring a short broom handle or piece of 1x2 lumber, put that on the starter and whack the other side with it.
If it now starts, your starter is likely at fault.

“Thanks. We have checked this and it is not the neutral safety of shift level sensor.”

I see. Is there any other info you’d like to get out there? I haven’t been doing my ESP exercises lately.

I would rig something up to be ready to hot wire the starter straight to battery voltage the next time it happens. I don’t know if you would. But that’s what I would do.

“I see. Is there any other info you’d like to get out there? I haven’t been doing my ESP exercises lately.”

Since I am not a mechanic I do not know what or what not you might wish to know or think is beneficial. But otherwise, I think term limits for all elected officials would solve a great deal of our political problems. Defining lobbying as bribery would help with the rest. Reality TV shows are poor excuses for entertainment. I don’t need a cell phone to survive and I do not know anyone who has actually been harmed by Obama care. Although I am a GOP ,the Tea Party is not my cup of tea. Feel more informed now ?

Apparently the relevance of the neutral safety switch is completely within what you know about already - or you wouldn’t have known to check it.

You seem to have objected to my statement. On a very regular basis people show up and give scraps of info to be followed by suggestions that are followed by “oh we already did that…” and “oh the mechanic checked that already…” This can sometimes drag on for days and pages and pages. Its preventable.

But its clear to me now that your Envoy was built by a GOP hardliner who added some special no-start programming to fluster the less hardline GOP members. The info is probably carried back to headquarters by special bugs planted in the car. Just be glad you don’t describe yourself as a Democrat - then it was programmed to never start at all. I think GM put out a TSB on that, but you won’t find it because the person who wrote it was described as a “liberal” and its release was quickly quashed by his GOP manager.

But seriously - if you can get 12V directly to the starter when this happens (jumper cables work) you can find out whether its the starter or not.