A while ago I was having trouble starting my GMPD4106 when the engine was hot.No problem cold by when it was up to temp and you pressed the start button it would "grunt" like the batteries were dead. I tried everything.Moved batteries closer to engine(3 ft. of cable), put in new batteries, put in new cables ( cables go directly from batteries to starter), added an additional solenoid, rebuilt the starter, etc.Nothing worked so I used it very little. Then I decided "the hell with it-I'm going to drive it anyway". At the same time I also made some mods to the starter relay by replacing it with a common solenoid and the start problem disappeared. To me this doesn't make sense. The starter was wired directly to the batteries and all the starter circuit does is engage the solenoid.
Its worked fine for a while now and gives no indication it will be a problem.BUT, every time I go to start it when the engine is hot I wonder "Is this the time".
I had a hot starting problem, but it was simply the ground cable on the starter was loose. So when it was hot it would expand and not make contact. Tightening solved the problem. Good Luck, TomC
I wouldn't connect batteries directly to batteries.
A disconnect switch should be installed.
Just my way and the way of every bus I have ever seen.
Don't neglect the ground side when troubleshooting electrical problems. When those electrons leave home they have to find their way back in order to do their job. Big heavy cables on the plus side and wore out ground strap on the return is a sure recipe for disaster.