no starter operation the engine will not crank over?

Hello, I am Danny.

I believe you might be having a problem with the starter solenoid that is located on the starter motor. If you have the starter motor removed from the car it can be taken to a local auto parts store and tested. They are subject to wear due to the numerous cycles of a car being started. I have attached tutorial links for you to look at explaining the starting system and related components, and how to remove the starter motor. Hope this helps and feel free to ask any questions if needed. Thanks for using 2CarPros.com. Danny-

https://www.2carpros.com/articles/how-a-starter-and-solenoid-works

https://www.2carpros.com/articles/how-to-replace-a-starter-motor

I am not confident the problem is the starter. There are no noises when the car fails to start. Usually when the starter is the problem, there are noises of some kind and usually the lights dim due to battery drain. Someone on another board thinks it might be the starter relay or the ignition switch itself.

Is there any way to test the starter and ignition switch without taking half the engine or car apart first?

Hello again.

The starter relay is located under hood in the power distribution module if you want to have tested. I have attached a picture and circled in red. I am also attaching a tutorial showing how to go about testing it. Hope this helps.
Danny-

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I had a friend over to help me with the IPDM box. Of course, I could not duplicate the problem while he was there. We did take half the replay box apart. It is very hard to gain access and we could not get all the wire connectors loose, which made it impossible to be able to access the starter relay.

Next step is to find a way to get the wire connectors dislodged so that I can remove the whole IPDM, which will allow me to access the starter relay. However, due to all the work necessary to get that box out, I wanted to have a new relay on hand so I could just replace it in case it really is bad. Seems like a worthwhile $20.00 or so investment in the part. But the problem is that I cannot find the starter relay anywhere (online, calling auto parts stores). Even a Nissan dealer says he cannot find a part number for this relay. For all I know, it might be permanently mounted and impossible to remove, thus requiring me to buy a new or used IPDM box and swapping that in.

In the last few days, the car has been starting fine, except for one incident on Wednesday when it did not start on the first key turn but did on the second key turn.

Hello again.

Here is the picture again of the relay in the IPDM box from my last post. It is just a $20.00 relay available from any parts store. I am pretty sure there is no reason to replace the whole IPDM. When I can access my research/diagram site I will get back to you.
Danny-

Did turn out to be the starter. Replacing it solved the problem. Thanks.

Good to hear, Danny L is one of your best! Please use 2CarPros anytime we are here to help.

Cheers, Ken

Thanks Ken!
Danny-