battery boost switch does nothing.

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the57man

Member
Joined
Aug 16, 2009
Posts
23
Location
Citrus Heights, Ca
2001 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. 
 

Wizard46

Well-known member
Joined
Mar 12, 2009
Posts
2,092
The house batteries will be connected to one side of the solenoid and the engine batteries to the other side. The solenoid connects the two together. Even low batteries will show some voltage on its side. Did You hold the boost switch while cranking.

The energizer wire should only see voltage while holding the switch.
 

emiddleb

Well-known member
Joined
Mar 22, 2009
Posts
315
Before you start tearing things apart, there's something you might try...  I've read in other threads (and experienced it myself one time) that if your chassis battery is real low, try holding the boost switch down for a couple minutes before trying to crank the engine.  Let the house batteries put a bit of a charge back into the engine battery first.  Sometimes this works when what you tried fails... did for me.
 

John Canfield

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Aug 8, 2006
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13,552
Location
Texas Hill Country
The Battery Boost switch is a solenoid that will connect the house and chassis banks together when a) the engine is running or when b) the Battery Boost switch is operated.

You will measure voltage on both sides of the solenoid irregardless of its functionality - on one side you are measuring the house bank voltage, on the other side you are measuring the chassis bank voltage.  The best way to troubleshoot the solenoid is to operate it and measure the voltage with a digital multimeter on both terminals - the voltages should be exactly the same.  If not, you probably have a defective solenoid.

I've had three or four of the Trombetta solenoids fail in maybe five years, if yours is 11 years old and just failed, then you are very fortunate.
 

JackTinAZ

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Joined
Jun 9, 2011
Posts
5
Location
Sierra Vista, AZ
On a service visit for other problems, the tech happened to discover that my battery boost switch wasn't even wired, so he fixed it without asking. As I recall, that, too was on a 2001 Adventurer which I no longer own.  Sometimes we tend to overlook the obvious in searching for a solution.
 

neil30076

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Joined
Jan 16, 2012
Posts
56
Location
Cary, NC
Have just experienced the same problem.  On my 2003 Brave, the boost switch did nothing. I did not check out the wiring diags, but i suspect it is hitting a solenoid that is in fact powered by the chassis battery, and if it is very dead, as mine was, it will not energise the change over relay to apply coach power across the chassis battery. My battery was down to less than 3 volts, so putting that across the coach batteries would have been a big drain. I disconnected the bad battery and took it back home to charge, and then load tested,  and now it is back in and doing what it should.
Why was it drained, you ask - Clifford alarm on for about a month seems to have something to do with it, and maybe the courtesy light over the console ( under the up front TV, was also on.
 

catblaster

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Joined
Jan 11, 2010
Posts
2,702
Location
Kissimmee, Floriduh
when I replaced my solenoids last spring, I found the contacts completely fried. Probably should have taken John Canfields advice on the trombetta's but I did add a manual bypass across the battery banks. All I need to do is lift the cover and throw the switch...good to go on all banks.
 
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