Looking for 1993 U240 coach wiring diagram. Thanks 😊
Terry,
Welcome.
12 VDC or 120 VAC?
And, any particular area/device you are interested in?
12v
Coach
Source of power to dash incl start lock switch
Terry,
A good place to start your troubleshooting is the IGNITION SOLENOID.
Open the dash (hinged in front by windshield).
Ignition solenoid is in front of driver's area.
Two large lugs-- one should always have chassis battery voltage. The other large lug should only have voltage (same voltage as the other large lug) when the ignition is on.
Let us know what you find.
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No juice to the hot side. If I jump from alt post on isolator to start batt post I get juice.
What is battery voltage at chassis battery? house battery?
Does the boost switch work?
12.7
14
Don't know
Engine running or engine off? The center (alt) post on isolator should not be hot unless the engine is running.
Cant start engine without jumper. I gotta trace some more cables.
Typical OEM 4-post isolator wiring connections:
Yeah, mine is 3 post aftermarket and now that I have rewired it the alt no longer charges
Where can I get a four post?
Better question...why four posts?]
The 4-post isolator fitted by the factory to older Foretravel coaches is a bit of a mystery. Several ideas found on this Forum over the years about why... Perhaps it was all they could get at the time - who knows?
You'll notice in the photo I posted that there is a jumper connecting the coach battery post to the "extra" 4th post on the isolator. So the 4-post isolator still functions the same as a 3-post model. It can be replaced with either a 3-post model or a 4-post model. They should both work equally well.
The Victron ArgoFET 3-post 200A isolator is a excellent choice - suitable for use on any Foretravel coach. It has virtually zero voltage loss between the alternator post and the battery posts, making it very efficient.
Amazon.com: Victron Energy Argofet Battery Isolators 200-2AC (2 Batteries... (https://www.amazon.com/Victron-Energy-Argofet-200-2-Batteries/dp/B00NT9MTMQ)
A photo and description of the cables at the
Isolator would be helpful.
Any paper work with the isolator?
Did it ever work correctly?
No paperwork
Don't know. New to me.
Don't know how to add pic.
Center post from alt
1st post to coach batt
3rd post to engine batt and dash solenoid
You need to get out your multimeter and do some basic charging system trouble shooting. The first diagram I linked in Reply #4 shows how a 3-post isolator should be connected. After you have the battery cables connected to the isolator, then you'll need the big engine running (whatever that takes).
With engine running, you can measure and record the voltage at the following points:
1. B+ output terminal on the alternator
2. ALT post on the isolator
3. COACH battery post on isolator
4. ENGINE battery post on isolator
5. The POS (+) post on the COACH battery bank where cable from isolator is connected
6. The POS (+) post on the ENGINE battery bank where cable from isolator is connected
7. BOTH of the large terminals on the ignition solenoid (under the lift-up dash cover in front of driver seat)
Let us know the results of these readings.
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Thabk you all..
Cables are good. Voltages are good...except no charging voltage to start batteries. Will be testing isolater in a different way.
To test diode-based isolator with three lugs:
Center lug is from Alternator B+ and with engine off, 0 VDC. With engine running (and around 1,100 RPM) in the high 14's.
One outer lug to chassis battery and will read chassis battery voltage with engine off. With engine on it should read in the lower 14's.
Other outer lug to house bank and will read house bank voltage with engine off. With engine on, it should read in the low 14's.
Yes, if batteries are deeply discharged and alternator output is insufficient to achieve target voltage, that is also OK-- just need to recheck when batteries charge rate is within the alternator's capability.
Let us know what you find.
Bats are fully chgd.
Need to test diodes
Then, my test immediately above should tell you what is going on.
Also a good idea to check the other/small wires/terminals on the alternator. The sense wire is small-gauge and have seen some not connected, some wires broken.
Thank you very much for helping me with this issue!
Internal reg. No sensing wire.
Alt will chg if there is 12v available at output post. There isn't preaumably because of the diode.
Very likely you have an incorrect alternator for a system with diode-based battery isolator. OE, and with a diode-based isolator, you need a DUVAC alternator.
There is about a .7 VDC drop across the diodes (turned into heat, which is why the aluminum fins to get rid of the heat).
If the alternator is putting out, say 13.5 VDC, the "far side" of the diodes and hence both batteries will only be charged at 13.5 minus .7= 12.7 VDC.
If not a DUVAC, you can either change the diode-based isolator or get the correct alternator.
Short term, you can move all the terminals in the diode-based isolator to one lug to get you where you are going.