This machine 2010 G976 @11k hours on it, has recently taken up a bad habit of cranky starting, once its running, its good. Not a bunch of smoke or anything abnormal. Warms up ok, make a lap or two around the yard. Then about a 1/4 mile down the highway it will just shut off like the key was switched off. You lose everything. Wait a bit and crank it up and take off again. It will run the rest of the day. We have been crawling thru this machine and not finding anything wrong. Thought I would hope to hook up a laptop and watch it die - in real time maybe see whats forcing the shutdown or something. Its not giving any codes that lead us to a problem.
If it has an electronic engine with both crank and cam sensor, it is possible one is communicating incorrectly with computer without dropping any DTC for you to see. Have watched a couple of video's that highlighted that they can fail and not log a code. The guy disconnected one at a time and seen what happened, found out the camshaft sensor was faulty.
Have you checked your relays with them removed from machine and powering up a 5-10 amp bulb for 10-20 minutes to see if they start to get hot and suddenly drop out.
Check each leg of ATO fuses to make sure the receiver from one is not loose and causing the computer to shut down instantly. Check all the power relays for loss across the two sides.
Test for AC ripple voltage coming out of your Alternator because computers do not like it, but some will shut down if dosed with too much AC ripple voltage. If you are going to test for it, do it when the engine is super hot and there is lots of extra electrical load as some faulty units only put out excessive when hot.
Often I find alternators full of dirt that I blow out with 150 psi of air, but be careful if the output post is live and uncovered.
My guess is something is dropping out under load when very hot, maybe it is not hot and still drops out?
Simon C
