battery boost switch does not boost like a booster should.

2001 Winnebego adventurer 32'. My engine battery was to low to start my engine yesterday, yes I know I shouldn't let it get that low but it happened, so I tried my battery boost sw. nothing. House batteries are fully charged. I used a test light and have voltage on either side of the solenoid. I don't think I should have voltage on both sides if the boost button is not being pushed. I disconnected the small energizer wire on the solenoid and there is still voltage on both sides of the solenoid as if its still energized. If that's the case, then I should have been able to start the engine. I'm confused.

C Nash

Senior Member
If you are testing on the correct sol sw there must be an open between it and your engine battery. You should not have voltage on both sides when the aux start button is not pressed IMO. Maybe some others can give an answer


Senior Member
You will have voltage on both sides of the boost solenoid. Voltage from the house side and from the Chassis side even if it is low. You should be able to energize the solenoid with a jump from the house side, if not then the solenoid is dead , this will be a test for the boost switch too. You can take a jumper cable from the house to chassis side and start.


Clay L

Senior Member
Below is a typical Winnebago diagram of the circuit. The solenoid is activated in two ways.
1) By voltage from the RUN terminal of the ignition switch.
2) By voltage from the momentary AUX Start switch on the dash.

These solenoids are noted for having high failure rates. The replacement is a Trombeta : Copper contacts 114-1211-010-03 (Winnie PN),
Silver contacts 114-1211-020 (Trombetta PN) Many people prefer the silver contacts but they can be hard to find.

You can get replacements in many places. I got mine at LICHTSINN MOTORS


Senior Member
Hi, Thge57man
Welcome to the forum... hope we can help..
Yes, power to both side of the solenoid. you could have dirty connections on the engine battery & or the house batteries
you could get voltage, but not enough amps to start the engine...starting current for a gas engine is around 300 amps..
I don't know where the boost switch get's its power from... if it's from the engine battery, and it is low, you my not have the power to energize the solenoid.
with the solenoid off there should be a voltage difference between the two sides, with solenoid energized, the voltage should be equal on both sides

Good luck, hope this helps