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[Larry Dedrick]

Anyone:
              Does anyone have an electrical schematic for a 2001 Beaver Marquis Amethyst (or at least Marquis) that would show the wiring related to the alternator and associated wiring. Specifically the sense wire and ignition wire coming from the alternator.
              I am wondering if the sense wire goes from alternator to ignition switch to isolator on the chassis side of the isolator.

                Thanks in Advance:       Larry D
            
                

[Edward Buker]

Larry,

I think one wire is ground, one wire goes to ignition, and I thought one wire goes to the battery side of the isolator to sense actual battery voltage. That makes sense to me given the ignition circuit voltage at the switch varies depending on load from the dash area. If you turn on dash items you will see the dash voltage gauge vary in voltage. If that was the sense wire then the alternator voltage would respond to that and it does not. I wish I was sure of the actual location but I am not.

You can test this a bit by adding dash load with the engine of fast idle and watching the dash volt meter while also checking the chassis battery voltage at the battery with the coach unplugged from AC. If the battery voltage is a constant and the dash varies with dash load then the sense has to be at the batteries. I would look for an extra wire on the isolator that is the same gauge as the sense wire on the alternator. It may be numbered or labeled to help. If it is not on the isolator look at other points common to the chassis battery + terminal. It could be on the + terminal of the starter solenoid also. If you figure this out for sure let us know.

Later Ed

[Edward Buker]

Larry,

I happen to be doing battery maintenance today and I peeked around the isolator, main fuses, and did not see a separate appropriately sized wire that came from the harness. The extra wires on the isolator on my coach come from the echo charger. There were two white chassis wires on one of the plus terminals of the chassis batteries. One may be ECM and the other could be alternator. You can go to the sense wire on the alternator which should have 12v on it. Turn off the chassis battery switch and if it still has 12V then you know it is tied close to the battery terminals. If you have the same two white wires on your chassis battery post then you could lift them one at a time and check the alternator sense wire for 12V.

Later Ed

[Steve Huber Co-Admin]

Larry,

Wiring diagram for 03 Marquis is on BAC site. Alternator wiring should be same as yours.
Select Private BAC Members Only below forum section.
Select  Sticky; Link to Coach Assist
When email comes up, click on link.

You'll find equip manuals (5 sections) for 2003 Beaver marquis. Alternator wiring is on page 5 of section 4.

Good luck,  Steve

[Larry Dedrick]

Steve and Ed:
                       Thanks for the information and suggestions. I finally gave up on tracing the sense wire and took the coach to Southeast Power Systems in Orlando. This is the facility that the alternator came from and the business that bench checked the alternator a few weeks ago. I thought all was well when I reinstalled the alternator, but my luck did not hold out.
                        The fix they did, was to run a new sense wire, with fuse protection, directly to the battery and all problems were over. One thing I do know is the original sense wire did not go to the battery or the isolator. Also I believe one of you may have suggested this as a fix some time back, when I originally posted the problem. I thought perhaps having pro's check and fix would be the way to go.

                       Thanks again for the Help:                   Larry D

[Edward Buker]

Larry,

Glad all is well now and that you are back in business. There is no reason for that alternator and wiring not to be very reliable. New sense wire should do the trick. You still have to wonder where the original went....

later Ed