Starter bad wire ?

[Bluridge]

After having sporadic "start" issues for a year (gee what part about "start" did I not understand) - it's not the battery, it's not the alternator. Had those checked out tonight after cutting through the hole to give the wonderful O'Reilly's tech access to the battery. Its the starter, and not a bad starter, probably. It's probably a bad connection based on the symptoms. Anybody know where this bad wire could be? Where should I start looking or directing someone more skilled than I to look.

2014 Thor Axis

[samven]

When you try and start the engine and it does not go, is there any noise. Your listening for a moderately loud click. If you dont hear anything then the computer could be blocking start or you have a bad connection to the starter relay. They use to call it a solenoid and may still but I stopped working on engines when they got too computerized. This relay takes a small current from the key switch and activates a monster relay(the click) that can handle the hundreds of amps needed to spin the engine. If you hear the click and nothing else happens then check the connections from the solenoid to the starter and the grounds to the chassis. If all these things are good you may have a bad spot on the starter. Then its just hit or miss if the starter stops on the bad spot or not. To find the solenoid follow the + battery cable (big one) Solenoids are usually mounted on the fender wall.

[Laco]

On my previous DP, after fighting intermittent starting issues for over a year, finally found a loose connection on the starter itself. Lots of black burn marks on the top of the starter. Cleaned up the connection, reconnected, problem resolved.

[Bluridge]

Thanks for your input. No loud click or clunk. When I turn the key there is complete silence. I can start the engine right up when I use the emergency start so does this make any sense at all? I would pay whatever it takes to make this go away but I don't even know what to tell a mechanic anymore.

[Laco]

Ok, my understanding of the emergency start, is about all that does is connect the house batteries to the chassis battery(s). The next question I would have; when you can’t start it and there is zero solenoid sound (that click) can you, or have you ever been successful in getting it to start without using the emergency start feature? If your answer to that is, never, than I would suspect something is reacting or overreacting to what may be a slightly low voltage issue, possibly the computer blocks the start process, or possibly the solenoid itself may be failing. Any mechanic will tell you, their biggest challenges are usually electrical problems.

[samven]

If your chassis battery is checking out good and I suspect it is since this is intermittent. I would look at the relay that ties the coach battery to the chassis battery. They must break the main line to insert the coach battery in parallel before the starter or the solinoid. I dont know exactly how they wire it but I bet there is a black box where the chassis and coach battery go in and a single line to the solinoid comes out. If the connections are tight there the problem has to be that box.

[Oneilkeys]

If the RV starts every time when the emergency start is engaged but does not start sometimes on just chassis battery power and the chassis battery checks out OK, then you almost certainly have a bad connection in your chassis starter system. The emergency start provides enough amperage along with the chassis battery to start the engine pushing thru your bad connection. The chassis battery alone does not. If you are knowledgeable about engines, you could get a starter system schematic (you have a Mercedes chassis?) and check all the wires. Probably will be easier to take it to any Mercedes or light truck mechanic and tell him you probably have a short somewhere in your starter system or a bad starter. It should be relatively easy for him to find and fix. This does not appear to be an RV problem.

[Bluridge]

Thank you for your input. I'm going to call the Ford dealer to see if they can check it out.

[Bluridge]

So the simple of all of this was start with the battery. Three times people held a diagnostic tool in their hands and told me that the battery was good. My neighbor told me "it's the battery"! But he was not able to tell me why he felt it was the battery when the diagnostics said it was a good battery. I had a shade tree mechanic tell me it was a dead cell and then when this weekend I smelled a sulfphur odor I was convinced - dead cell. So this morning I took it to the Ford dealer (the battery went out of warranty last week ) but they found a DEAD CELL! New battery installed and here we go - literally. KISS