Battery Boost / Auxillery Switch

1. IF the system is working, you will hear the solenoid click when the dash button is pushed. Have someone at the solenoid listen for the click
2. IF the chassis batteries are completely dead or below 9 volts, MOST Boost systems will NOT work. It is the fault of those dead batteries drawing needed current instead of going to the starter. If this is the case. Run the Genset or leave plugged into Shore Power and hold that button or use a toothpick to hold it for about 30 minutes. This gets a surface charge on the Chassis batteries. Then try to start the engine.
3. The Boost is ONLY for dead chassis batteries. If your coach batteries are DEAD, then the boost system will not function. It takes current from the Coach Batteries to engage the solenoid. Doug

dalenoel wrote:
I have the Neptune with a 300 Cummins and the only time it does not work is if the shift is not in Neutral. There have been times I need to hunt for the exact spot.

X2, I'd try this and also check for continuity on the switch terminals.

I have the Neptune with a 300 Cummins and the only time it does not work is if the shift is not in Neutral. There have been times I need to hunt for the exact spot.

Yes, Freightliner chassis, Cummins 300

Still have the Holiday Rambler Neptune if so what chassis/engine etc