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Topic: Boost Switch Issue (Read 1411 times) previous topic - next topic

Boost Switch Issue

I don't want to start a debate about the use of the boost switch. Mine has always " lit up " whenever I wanted to use it, but recently doesn't light up anymore.
Can someone WALK ME THROUGH the best procedure to figure out why ??
how do I pull the switch?
how do I test the switch ?
How do I test the bulb in the switch ?
Where would I purchase a new bulb, if that is the culprit?
Thanks

Re: Boost Switch Issue

Reply #1 –
Bulb is a Napa 17037...FOT was out a couple weeks ago.
John

Re: Boost Switch Issue

Reply #2 –
The switch just "snaps" into a hole in the dash.  You have to access the rear of the switch to replace the bulb.  You may be able to get at the bulb without pulling the switch out of the dash - depends on how much room you have to work behind it.

Re: Boost Switch Issue

Reply #3 –
Yea, you an either snap it out of there from up top or unscrew the switch control base and push it up. The first photo shows the little clip that holds the switch in. The others show how to change the light bulb.
jor

Re: Boost Switch Issue

Reply #4 –
Wow...Jor, what a great help. Thanks to all.
Shouldn't I test the switch, in some way, BEFORE I replace the bulb? Or test the bulb.
Sorry if this seems dumb. Electrical isn't my strong point.
No comment, Twig.

Re: Boost Switch Issue

Reply #5 –
Pretty easy to test:

Either use a voltmeter at the "signal terminal" of the boost solenoid, or more likely, you can just hear it "click" when it is turned on.

Have someone turn it on/off/on/off while you are back at the solenoid.  Hearing the click will tell you that both the signal is reaching the solenoid from the switch AND that the solenoid itself is working.

Re: Boost Switch Issue

Reply #6 –
Quote
Shouldn't I test the switch, in some way, BEFORE I replace the bulb?

Bulbs are cheap. Just replace them all while you're at it.
jor

Re: Boost Switch Issue

Reply #7 –
Quote from: GleamB –
Shouldn't I test the switch, in some way, BEFORE I replace the bulb?
Brett beat me to it.  Here is my much more wordy way of saying the same thing he did.

If you wish to test the function of the boost switch, can be done in one of two ways.

1.  To test the switch remotely, you need a way to monitor the voltage on both battery banks simultaneously.  In most coaches, this can be done by using inexpensive lighter plug volt meters.  If you have two lighter sockets on your coach, one is usually powered by the coach (house) battery bank, and one is usually powered by the chassis (start) battery bank.  The idea is to draw down the voltage on the start batteries by turning on the headlights (high beam).  Leave them on for 5 minutes or so, then turn them off.  Now the voltage on the start batteries should be lower than the voltage on the house batteries.  If you then activate the boost solenoid by turning on the boost switch, the two battery bank voltages should instantly equalize.  If so, the switch (and the solenoid) works.

2.  OR, you can test the boost switch directly by checking the voltage at the boost solenoid.  The small terminal post on the boost solenoid is powered by the boost switch.  If there are 2 small terminals, one is powered by the boost switch circuit, and one is a ground connection.  With the boost switch off, check for voltage on one or both small terminals on the boost solenoid.  Neither should have voltage showing.  Then turn on the boost switch.  Now one of the small terminal posts should have 12 volts on it.  if so, the boost switch is working.

With the boost switch off, there should be no continuity (open circuit) between the large posts on the boost solenoid.  With the boost switch on, there should be continuity (closed circuit) across the large posts on the boost solenoid.

Re: Boost Switch Issue

Reply #8 –
Couldnt you check continuity at the switch? on the tabs?

Re: Boost Switch Issue

Reply #9 –
Quote from: DavidS –
Couldnt you check continuity at the switch? on the tabs?
Checking at the switch doesn't tell you if the signal is getting to the solenoid.  But it would tell you if the switch is getting power...

Re: Boost Switch Issue

Reply #10 –
OK
So where is the solenoid and what does it look like on my coach
I will get bulbs
Thanks

Re: Boost Switch Issue

Reply #11 –
Quote
So where is the solenoid and what does it look like on my coach

I think yours is on the back wall of your engine compartment. The photo with the arrow shows its location on our 99. The next photo shows what the boost switch probably looks like. (you can see the label I added) Kinda looks like a little can. This is on a 97 but I moved it to that location from the original.
jor

Re: Boost Switch Issue

Reply #13 –
Where was the original location jor?

Re: Boost Switch Issue

Reply #14 –
Not jor but on a '97 OEM it was mounted on a plate  (along with several other electrical things) just behind the left rear duel tire.  Opening up the door behind the tire and looking around the OEM muffler it can be seen mounted on the frame rail. This was the location for several years.  Verrrry poor spot due to water spray getting all over everything on that panel.  Last time I checked most electrical connection don't like moisture.

Mike

Re: Boost Switch Issue

Reply #15 –
On earlier coaches, behind the driver's rear tire.  A TERRIBLE location.

Many of us have moved it-- either into the front of the engine room, or in my case into the "electrical area" at the foot of the bed.

Clean and dry is good for electrical equipment. 

Re: Boost Switch Issue

Reply #16 –
 went to the local NAPA.....didn't have the bulb
got the switch out of the console without breaking it.....yeah!
can't figure out how to access the bulb to replace it. There is a little release looking thingy in the center of the top of the switch....do I depress it and pull the two contacts??
When I disconnected the bottom half of the switch, I got some "arching"....sparks!!??? Can't pull it out further due to no play in wires. Do I have to remove the console around the steering column??? How???
Hope I didn't open up a " can of worms"
I HATE getting beat up by inanimate objects

Re: Boost Switch Issue

Reply #17 –
Quote from: wolfe10 –
Yup, looks like a starter solenoid: Amazon.com: Cole Hersee (24059-BP) 12V Insulated SPST Continuous Duty...

Brett I think that on this you need to insult a persons intelligence sometimes and point out that "looks like a starter solenoid" means "expensive and built to be on continuously."

Starter solenoids are inexpensive and meant to be engaged for short periods of time. The Cole Hersee solenoid referenced above can be "turned on" for extended periods of time to allow the chassis battery to charge from the house side of things.

Art

Art
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Re: Boost Switch Issue

Reply #18 –
Art,

Absolutely correct.  The "looks like" I posted is correct.

But, as you post, it must be a "constant duty" solenoid with pretty high amp rating.

And, if the boost solenoid has failed, let us know and we can post a PN.

Re: Boost Switch Issue

Reply #19 –
Quote from: GleamB –
went to the local NAPA.....didn't have the bulb
got the switch out of the console without breaking it.....yeah!
can't figure out how to access the bulb to replace it. There is a little release looking thingy in the center of the top of the switch....do I depress it and pull the two contacts??
When I disconnected the bottom half of the switch, I got some "arcing"....sparks!!??? Can't pull it out further due to no play in wires. Do I have to remove the console around the steering column??? How???
Hope I didn't open up a " can of worms"
I HATE getting beat up by inanimate objects

"Hope I didn't open up a can of worms."

Yeah too late for that.  Either let it sit overnight and attack the mechanics fresh in the morning or put it back together and close the dash.

Taking those plastic switches apart requires finesse and patience.  My advice?  Don't work to a deadline.  Take the switch our completely, isolate the hot lead, and work on the switch in a baking pan on the dinette.  Line the baking pan with a rag and cover anything that might go boing before you release it.