Cruisers Forum

Main Forum => General Discussion => Topic started by: jmosier on January 05, 2013, 11:25:13 am

Title: white switch on the dash
Post by: jmosier on January 05, 2013, 11:25:13 am
Can anyone tell me what the white switch is for .  It is located on  the left of the Steering wheel.  It is the only white switch on the dash so it must have been an add on but it does not seem to do anything.
Title: Re: white switch on the dash
Post by: dickreid1 on January 05, 2013, 12:05:59 pm
That switch connects the house batteries to the engine battery for as long as you hold it in.  This charges the engine battery.  Do not use it to try to start the engine because the wiring is not heavy enough.
Title: Re: white switch on the dash
Post by: lmichael on January 05, 2013, 04:51:33 pm
Now I was told the switch was for emergency starting when your vehicle battery was dead????
Title: Re: white switch on the dash
Post by: bobander on January 05, 2013, 05:05:19 pm
Yes, it is for starting when the vehicle battery is dead.  The issue is that the wire gauge is too small to carry the full starting current and the voltage drop will be so much that it won't start.  So you have to hold it on long enough to charge the vehicle battery enough to start the engine from the vehicle battery plus what little current comes when the switch is held on.

How long?  That depends on how dead the vehicle battery is, just hold the switch on and try to start the engine, if it doesn't turn over quickly turn off the key and wait and try again.
Title: Re: white switch on the dash
Post by: jmosier on January 06, 2013, 01:03:07 pm
Thanks everyone!
Title: Re: white switch on the dash
Post by: keelhauler on January 07, 2013, 12:29:14 pm
My old 2551, the switch was an on-off switch rather than a mementary that you have to hold.

I replaced the switch in my new 2552 with an on-off switch so when I'm parked a long tome and the truck chassis battery gets a little low it will recharge it. I found a switch at an autoparts store that fit right in the same slot and you just unplugged the wires and plugged them into the new switch. A no brainer 5 minute job.

I believe they have a relay in the circuit that cuts off this connection when you are cranking, so you can't pull power from camper batteries when you try to start.

It sure works better than holding the switch manually.
Title: Re: white switch on the dash
Post by: TomHanlon on January 07, 2013, 02:37:37 pm
I believe they have a relay in the circuit that cuts off this connection when you are cranking, so you can't pull power from camper batteries when you try to start.


Are you sure that there is a relay in the circuit. It does not sound right to me as the switch is for using the camper batteries to start your engine in an emergence.
Title: Re: white switch on the dash
Post by: lghjr on January 07, 2013, 08:15:29 pm
My 2007 had another start relay on the fender driver side that connected the house and chassis battery using the dash rocker switch, BUT, as has been stated it was for boosting not starting because of the gauge of the cabling from the house batteries.  I do not remember whether or not it was wired to disconnect on cranking but may have been.  Normally start relays are wired in the latching mode but I never had to check out exactly how that relay was wired.
Title: Re: white switch on the dash
Post by: Ron Dittmer on January 10, 2013, 01:22:28 pm
I don't depend on that switch.  If my chassis battery is dead, I would surely first try it, but....
I really plan to use long jumper cables from the coach batteries.  On our 2350/E350 all batteries are on the same side of the rig and not that far from eachother.
My backup to that is to use the "start" feature on the battery charger we carry along which would run off the generator.

If not to help myself, then to help others.
Title: Re: white switch on the dash
Post by: gl1500 on January 16, 2013, 02:28:11 pm
I had a dead battery on our 2552.  Dead meaning it did not have enough power to turn the engine over.  I held the switch for about five minutes and then released it and there was enough transfer of power to the chassis battery to start the engine.  I like the idea of having a switch you do not need to hold.  In aviation we have switches to be used for emergency use with a cover that when closed goes automatically to the off position.  I think that would be a good safety item for this switch.
   Bob