Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

Re: Engine batteries

Reply #25 – July 12, 2012, 10:11:22 am

Dwayne,

You shouldn't have to remove the alternator to be able to determine how it should be wired.  Have you looked at the alternator manufacturer's website to wiring instructions.  I would do that and then trace out what wiring connections you have.  At that point, contact the alternator manufacturer's tech line.

And you really need to identify the two solenoids.  As I suggested, the one in the battery compartment is probably the boost solenoid.  I doubt both solenoids clicked when someone hit the boost switch.  Have you compared the wire numbers on the solenoid behind the driver's rear wheel to determine what it does?

Brett

Quote Selected

Re: Engine batteries

Reply #26 – July 12, 2012, 01:07:27 pm

I wasted an afternoon changing that solenoid.  It looked terrible but it tested OK.  I did hear a very loud click at the solenoid in the battery compartment when the boost switch is activated so I guess it is safe to assume it is functioning.  The light on the switch itself functions as well.  I'm fairly confident that the wiring at the alternator must be the culprit as it was the only thing messed with from before when everything was working as it should be.  I am going to call the tech line but I'd like to know, on my particular set-up (which should be the same as yours), which wires supposed to be present.  I know the main power to the isolator is one wire.  The sense wire to the chassis battery is the other (I think) and I have a third one that I don't know what it is and didn't yet try to trace it.  Then they have that jumper wire.  The reason I'm concerned and would like to know what is supposed to be there is I looked at the website for the Hehr 25-15 190 amp. and they show more than the number of wires connected to my alternator.  I think these guys in Jackson just cut wires.  Really need to know what was stock as far as wires present and where they go.

Quote Selected

Re: Engine batteries

Reply #27 – July 12, 2012, 05:06:05 pm

Dwayne,

You're on the right track.  The big wire is the output of the alternator that runs to the center terminal of the isolator. 

One of the other wires is the ignition wire.  The other is the battery sense wire.  Here's how to tell them apart.  First, disconnect both small wires from the alternator.  Be careful because one of them will most likely be hot and you don't want to short it to ground.

With the ignition key off, one wire should show 12 volts or so to ground, the other should show zero.  The one that shows 12 Volts is your battery sense wire.  It should connect to the terminal labeled S on the alternator.  Make sure it isn't hooked to the terminal that says R (some people do this by mistake as it's also called a Remote sense wire.)

Now turn the ignition key on.  The wire that showed 0 volts with the key off should now show 12 Volts to ground.  That is your ignition wire, it hooks to the I terminal on the alternator. Remove any jumpers which were added by the installer. This should make your alternator work properly. 

It's possible, considering the way it's hooked up now, that there is a problem with the ignition wire and that's why they connected a jumper to make it hot all the time.  That will be a problem.  If this is the case then you will need to find the break in the wire between it and the ignition source.  Since I don't have a wiring diagram for your coach I don't know if the wire runs all the way back from the ignition switch or there is some other scheme for making it turn on and off with the key. 

Hopefully Brett will see this and check what I'm telling you.  My coach is a different model but I think they all used the same basic scheme.  You might want to check your wires as above and then call tech service at Delco, that's what they're for. 

Chuck

Quote Selected

Re: Engine batteries

Reply #28 – July 12, 2012, 05:28:18 pm

Chuck,

I have both a different alternator and a different isolator system than Dwayne,  so telling him how mine is wired won't help.

My suggestion to Dwayne was to get the schematic for the alternator HE HAS and wire it according to their instructions.  If is has an external sense wire, it should go to the chassis battery terminal of the diode-based isolator.  If it has/needs an ignition hot wire, there are lots of ignition hot sources in the engine room on all our coaches.  No need to trace from the front.

Brett

Quote Selected

Re: Engine batteries

Reply #29 – July 13, 2012, 10:15:06 am

I called FOT and talked to Mark.  James is on vacation.  Mark said that truck shops frequently install alternators that do not work with their set-up.  I'm thinking my auto electric guy was on track when he told me to take it off and bring it to him.

Quote Selected

Re: Engine batteries

Reply #30 – July 13, 2012, 05:21:21 pm

Removed alternator and took it to the auto electric shop.  Mark at Foretravel said that most of the alternator arrangements during those years were the same.  The auto electric shop guy thinks that the ignition wire had a plastic plug kind of deal on the end of it and he showed me the kind of alternator he suspects it should have.  Can anyone confirm or refute that any of the wires going to the alternator are anything other than a round bolt over connector?

Quote Selected