12 Volt issue

[PeteB]

I would appreciate any help on the following issue that I just began to have. I have a 2004 Itasca Horizon 40AD with a ISC 350. When I turned the engine off after an 8 hour run, the 12V to the coach went off as well. As long as I had the key in the first position (accessories) or the engine running the 12V would be on. 12V disconnect switch had no effect when key was off. I cycled the key while pressing the battery boost switch and after a few tries the 12V stayed on and all was well during our stay. On the trip home the same thing happened so I turned the switch back to the first position and then turned the 12V system off with the disconnect switch before I turned the key off. 12V went off as expected and I turned the key off, then turned the disconnect back on and all was well. I assume that the problem lies with one of the relays in the elect compartment but am a little confused by the symptoms... any help would be greatly appreciated.

Sincerely,
Pete

[RickO]

That's a pretty weird one Pete but I'm betting our experts will be along shortly and probably point toward the isolator/bird relay... although I'm struggleing with exactly how that might cause these symptoms.

Best of luck...

rick

[RJay]

I would start by checking the battery boost solenoid, then check your coach batteries.

[Smitty3509]

I wouldn't think it's the battery boost solenoid, but on mine I have a electrical switch to a solenoid that disconnects the coach batteries. That would be my guess, something in that circuit. The battery boost ties the coach battery system and the engine battery together, and that solenoid has some weak contacts (I've replaced mine), but should not cause your problem.

[wa8yxm]

Two guesses, the battery boost is not on the list.

1: The House batteries (Dead as a door nail perhaps) voltmeter to the battery, 1B: the connections to said batteries (Corrorded to the point of no connection)

2: The house battery (AUX) disconnect.. ON/OFF/Defective?

[hamguy]

Quote:

Originally Posted by Smitty3509 I wouldn't think it's the battery boost solenoid, but on mine I have a electrical switch to a solenoid that disconnects the coach batteries. That would be my guess, something in that circuit. The battery boost ties the coach battery system and the engine battery together, and that solenoid has some weak contacts (I've replaced mine), but should not cause your problem.

I just replaced my isolation solenoid Thursday. Second time. The contacts get cruddy (term of art) and don't transition fully. But they are cheap.

[Smitty3509]

Quote:

Originally Posted by hamguy I just replaced my isolation solenoid Thursday. Second time. The contacts get cruddy (term of art) and don't transition fully. But they are cheap.

Hamguy, the next time you replace that solenoid, be sure you get the one with silver contacts, not the stock one with copper contacts. There is a really good thread here in the Winnebago forum, somewhere.

[PeteB]

Thanks for the info. I will check a few of the items suggested and post the results. I did load test the batteries and they tested OK so I believe that they are still in good shape.

Pete

[wa8yxm]

Coming off the batteries there should be a fuse or breaker, on my coach it is a self resetting breaker (Thermal) but the schematic for my battery control center shows two post type (PUSH HARD TO RESET, Up in this case) manual reset breakers in parallel.

Different coaches have different style systems.

The battery disconnect control SWITCH failed on my rig, when this happend I do not recall if the engine supplied house power or not,,, (I bypassed the solenoid fairly quickly, ran Generator till I bypassed and fixed the switch a day after that)

But then I know how to do all that stuff.

And on my coach, It is easy,, Did not even need to "Contort" (So many jobs are best done by a contortionist) as I do it standing up all 6'3" of me.

Check for power down the line, Start by reading voltage at battery, then move negative lead to chassis,, Then move down the positive line to the Battery control solenoids, and beyond,, When you see a zero, you found it.

or use a 12 volt "Trouble light" (I have 2 of those) and when you see dark, you found it.. I like the lights better as they provide more load.