My '08 Navion ('07 V6 chassis) has the same problem. Occasional no start. I posted a thread earlier this year. Took the RV to Mercedes and they replaced the ignition module. NO help. I am interested in tracking down the "braided" ground cable from the engine to chassis to check that. Anyone now where to start looking for it on the V6? I am still of the opinion that it is the starter or starter solenoid but want to check the ground cable first.