Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 12, 2025 ...

When it comes to electrical I'm lost. 😔

When you are lost, you need a map.  The "map" to your 12 volt chassis electrical system is the B-2126 Automotive Wiring Diagram.  It should be found in the Owners Manual.  If you do not have this schematic (along with B-2037) then you are truly wandering aimlessly.

When I try from the regular batteries I can't even get headlights. I hit the "boost" switch and everything seems to work.

That's why the electrical schematic is so important.  You need to understand how and where the boost switch connects the two battery banks.  Usually, using the boost is like putting jumper cables on a car battery.  By that I mean the electrical path from the start battery to the starter is still the same.  You are just adding additional "juice" to the circuit by connecting the house battery at the positive post on the start battery.

Tim's advice (above) is very good.  If the start batteries are really fully charged, then one (or more) of the battery cables may be loose or badly corroded, not allowing current to flow from start battery to starter.

How do you know the batteries are fully charged?  How and where are you reading the voltage?  What is the actual volt reading?

Electricity, especially the 12 volt kind, is generally pretty simple in theory. The practice gets a bit more complicated.

I normally start at the part that isn't working and work back toward the power source, but in this case I think you will find the problem faster if you start at the batteries.

First, completely disconnect the START batteries. That means not just the red and black thick cables  but also the cables that connect the batteries together. Start with the negative side (black cables). Before you try to remove a connection, see if you can move it any. Make note of those for later. Once all the negative connections are off, repeat on the positive side. Again, make note of any loose connections.

Now, clean each post on all batteries. Once they are nice and shiny check the voltage on each battery and note what it is. A day or so later come back and check each one again. They will be down a bit, but each one should be down about the same amount, maybe 0.2 volts or so. If any of the batteries is down significantly more than the others I'd suggest replacing the batteries.

Assuming that the batteries are fine, it is time to reconnect. Clean all of the connectors you removed earlier and touch up the batteries as well. Reconnect in reverse order (positive first, then negative). Remember your notes about any loose connections? This is when you pay close attention to those. Make sure that they are good and tight. If you can't get them tight it is time to replace that connector.

Once everything is reconnected and tight, try the lights. Do they work? If not, you are going to get a bit dirty. You will need to find the other end of both the positive and negative cables. At least one, and probably both, will be located under the engine somewhere, perhaps on or near the starter. Make sure those connections are clean and tight. Check your wiring diagrams/schematics for hints.

You might try a shortcut if you are willing to spend a bit of money. Find a place on the engine where you can attach a ground cable. Figure out how long you need and what size ends you need. Go to your local parts store and buy a cable of the proper length and have them put the proper ends on it, if it doesn't already have them. Hook up that cable and see what happens.

If that solves the problem you can either leave the extra ground cable in place or fix the original one.

My guess is that the problem is most likely located back near the start batteries and is probably a loose connection, a dirty connection, or both.