2010 Cat 252B Intermittent Wiring Issue

I have a 2010 Caterpillar 252BII with about 350 hours on it. It's been having some intermittent wiring problems. I would say about 5% of the time, the machine will not start. No power making it to the solenoid. When this is happening, there is power leaving the ignition switch, but it doesn't make it to the solenoid. The first time it happened, I pulled the cab apart to get at the ignition switch and do some testing. That's when I found that there was power leaving the switch and not making it to the solenoid. I had a Finning tech come out to look at it, but it actually started when he showed up. To make a long story short, does anybody have any idea where I could get a wiring diagram for a 2010 Cat 252BII? I would like to pick up the ignition wire somewhere in the engine bay, before the relay. Any help you could give me would be appreciated!