Funny you mention starting issues. I am sitting in Grants NM with fully charged house and chassis batteries and can' get enough motive force to spin this ISX fast enough to start. I bought this vehicle (2006 Phenix 440) last spring with 93K on it. it has always seemed to turn over slowly unless the house batts were engaged. Yesterday morning I left Raton NM and drove to Grants NM. We stopped at the Walmart there and when we came out the engine wouldn't crank. Called a local garage, they came out and jumped me and even with all the batteries engaged it barely started. I sat at the KOA here plugged in all night and the house and chassis batts all were showing almost 14 volts. I engaged the boost to start it and it cranked a few revs and was done. My guess is my starter is hosed. I haven't taken apart any cabling to inspect grounding issues. Does anyone have any thoughts/experience on this one? BTW it was 38 degrees, so, not ridiculous starting conditions.
Mike,
How old are the chassis batteries-- while they may show a full charge, under load their voltage could drop significantly. I would fully charge them and then have them load tested.
And, certainly, a loose connection on either positive or ground side can cause the same thing-- insufficient power at the starter.
Since it does not appear that boost helped, either boost solenoid is bad, house batteries are also low OR the issue is on the ground/negative side. So certainly check the ground cable from engine to batteries.
Start with removing, cleaning and tighten all battery connections.
At 38 degrees, I would be using the block heater for minimum several hours before starting. Anything you can do to lessen the load on the starter, such as warming the oil up a bit, is helpful.
Would this coach have the Aqua-Hot engine pre-warm setting. That has always made cranking in colder weather real easy for my coach. Best of luck.
Raymond
Your batteries are at the end of their life. Check the grounds too but I bet you should look at new batteries as well as your starter.