1982 Winnebago Itasca Spectrum Mini-12 volt charging issue

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RobbyBKing1982

New member
Joined
Feb 1, 2025
Posts
1
Location
Casper Wyoming
Hello all from the cold and very Windy Wyoming Winter wonderlands! :)

I have a rather unusual problem going on with my 82 Itasca Spectrum Mini. The RV sits on a Chevy C-20 truck chassis with a 350 small block 4bbl carburetor turbo 300 automatic transmission. The charging system...IE engine alternator is not charging suddenly after stopping for fuel two days ago. Supplementing with running the on-board Onan generator (good ol green mean tough n robust 💚) unit which would run even with a dead short across it!

After getting the RV fueled up I proceeded to start her up, cranked just fine and turned over. Once I let the ignition switch return to the resting point, or run point, there was a whine for a few seconds then the engine died. During this whine I noticed the charge indicator on the dash (standard charge voltage measuring indicator of 8 minimum to 18 maximum, spiked wildly and went down to its lowest point as the engine died. Usually when the ignition switch (key) is in the run position, that charge indicator reads something with the engine is not running or started.

So I proceeded to restart but nothing happened and that battery voltage indicator was still at its lowest point. I then checked the RV battery indicator meter on the control center which uses a single meter and a momentary contact rocker switch to see either the engine battery status or the house battery status. Both batteries had sufficient charge to crank the engine. But the engine would not start ...not unless I held the momentary battery boost switch in MOM position. Then the engine would run. But if I let go of the MOM switch and the switch returned to its resting point, the engine dies. No voltage feeding the ignition system to fire the plugs unless I hold the MOM switch in it's MOM position.

I installed large blade switches a couple years earlier to be able to disconnect the vehicle battery from circuit as well as one to connect both the vehicle battery and house battery together in parallel when I needed extra reserve current for overnights when running the heater or fridge or to charge small devices like cell phones or power the house LED lights or small inverter for running the tv or radio or satellite 📡 🛰️.

Long story short ..I have to run the generator while driving to keep charge on the batteries. The alternator on the engine seems to output a small amount of charge voltage...roughly 12.2 to 12.4 but drops when external head lights are turned on or when brake lights come on and use of the turn signals. I have to keep the Onan generator running while driving to maintain sufficient charge and voltage levels so that no brightness sags occur on the parking/running/headlights in normal driving activity.

I apologize for this incredibly long first post. I tend to ..🎵ramble on..now's the time and the time is now...sing my song...I go round the world and find my girl..🎵😉 Led Zepplin-Ramble On.

Any advice and a wiring diagram or schematic would be much appreciated! I am a retired radio and television broadcast engineer and mechanic and electrical engineer. Im just puzzled and lost without some road map to follow. 😎
 
Sounds like a shorted (and likely now open) diode in the alternator regulator. But your issue having to use the house batteries to get the thing to run is curious. Even with the alternator out of the picture it should still run on the chassis battery. Almost implies an external fault and the battery combine is backfeeding some circuit. I would approach it from the perspective it's a chassis issue, using OEM chassis electrical documentation but just to eliminate a variable, you can pull the alternator and take it to an auto parts store to test. Then if you have to chase down a popped fuse, relay or fusible link you're at least running a known working alternator.

Mark B.
Albuquerque, NM
 
Hi Robby, welcome to rvforum!

My go-to answer for weird electrical problems are (in any order) battery age and grounds with high resistance. If your batteries are five years old or older, replace them regardless of how they might load test. And Mark's suggestion of getting the alternator tested is a good one.

Winnebago might or might not have wiring diagrams online for your unit, I haven't checked in a while how far back they go now. As far as the chassis electrical diagrams, Winnebago Owner Relations might be able to email you a file or two if they have them available.
 
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