Coach power relay

[Gene Obie]

Packed up camp today and after disconnecting shore power I found stuff started being intermittent. Water pump would turn on a few seconds then off, sewer hose retract would just click when pressed and finally shore power retract just stopped working.. and finally no DC power at all inside the coach. Was just going to head home and deal with it there until I found I also couldn't retract the bedroom slide (odd the other 2 worked). Anyhow, after some time of trying to find the problem I discovered after cycling the "Coach Power" switch about 20times the interior lights flickered a few times then came on and everything started working again. The previous owner had told me to never use the "Coach Power" button and it was taped off - in hindsight maybe because he had a problem with it. So it seems the coach power solenoid is bad ( I could hear the clicking back in the battery bay).

I'm tempted just to bypass the solenoid and effectively disable this "Coach Power" function? Any reason not to do that? Doesn't seem like a very useful feature and sure caused me a big travel delay today. I still have the manual coach isolation switch and all the 12V breakers inside so can't see a good reason to have this feature?

[Fred Brooks]

   To get you home, remove the battery cable from one side of the solenoid and install it on the other post. Choose the cable with the most slack. I do not use the "salesman switch and solenoid"  on my coach, I use the master battery disconnects when she is in storage. Fred

[Joel Ashley]

Many here have done just that.  The switch is called a “salesman’s switch” for dealers’ convenience on show lots.  It wasn’t designed to be turned on and off constantly by owners, and only affected some interior 12v circuitry.   Our switch had to be replaced by BCS when the rig was relatively new, though I had used the switch little.  The problem showed up at closing time just as we were hitching up to leave after several days service.  Ken, my service advisor, had 3 guys stick around and also replace the “latching” solenoid as a precaution.  I was advised in no uncertain terms to leave the switch on, period.

I’ve not had to do it myself, but I think those that have simply connect both large wires to the same bolt on the solenoid, effectively bypassing its contacts that can pit or corrode.  Others here can advise further.  I assume you know where the solenoid is.

Joel

[Adam Hicklin]

For future reference, where is that solenoid?

[Gene Obie]

On my coach it's in the distribution/fuse box above the batteries - to the right of the larger Big Boy relay.

[Joel Ashley]

For myself and many, Adam, the solenoid is where Gene says, in a fuse panel above the batteries and in there on the wall to the right.  However your coach is an earlier and larger model than ours, and the solenoid may be placed differently.  It’s pretty much a plain old metal “Ford” can solenoid and shouldn’t be too far from your 200 amp fuse buss(es) and the house batteries.

Others here with coaches more similar to your ‘98 Marquis should feel free to contribute.

As Fred suggests, connecting the two large solenoid wires on one post removes the solenoid’s potentially problematic innards and the entry door’s “Coach Power” switch from the system.  Even dealers have been known to not use the switch, but rather the Mains to preserve power on their lots.  If you do the “bypass” and later sell the rig you should advise the new owner that the door switch is inoperative, so they don’t misinterpret it’s usefulness and fail to shut off the Mains as needed.

Joel

[Eric Maclean]

Gene as many here have already stated the salesman switch's main function was to provide a quick and easy method for the salesman to power up the 12 volt side of the coach for prospective buyers to look through the coach.
In real life that same switch gets inadvertently turned off creating all sorts of problems with clock resets etc .
They placed  the switch in a spot irresistible for kids.
Many here have simply bypassed the switch as suggested in prior posts and as Joel mentioned once it's by passed you have to remember to use the manual battery disconnect in the battery bay when storing the coach without shore power.
With that said my 1997 coach has no main battery disconnect and I still use the salesman switch if only infrequently although if the solenoid were to fail I would probably just by pass it as well.

However be aware if you choose to replace the solenoid it is not just a regular ford style solenoid as mentioned above it is what is known as a latching solenoid meaning it stays in which ever position it was last commander to with out having to have a command signal present to hold it there like a regular solenoid would.
Hope this helps
Eric

[Joel Ashley]

Thanks for clarifying my errant observation, Eric.

Joel

[Gene Obie]

Thanks for all the info, I'm just going to bypass it.

On another note, while troubleshooting this I see all those high amperage fuse links in the distribution box and was happy none of those were blown. Does anyone care a spare of one of these for emergency? Not sure where I could even buy one?

[Steve Huber Co-Admin]

Gene,
I carry a set as they are normally not available at a local hardware shops (at least near me). They can be obtained on Amazon. Just be sure to get the right length. https://www.amazon.com/s?k=anl+fuses&ref=nb_sb_noss
Steve