Need help

Regulator faulty

gas or diesel

If this on your 8.1 Chev(Workhorse), I would check the connectors on the alternator. Verify that it is plugged in tight. Make sure there is no damaged wiring at alternator.

Read the manual but I believe that light generally says the alternator is having trouble.
I would think any decent shop knows this.

Thanks for replies
It is in a Workhorse Service shop right now, and they have no clue as to what is wrong.
having done all the checks on their list
MANUAL said poss. Alternator but that is not so

I've seen bad alternators bench test good.

As suggested, I'd also check the connections. I had a car once that the wires had corroded inside the alternator plug. Just a fluke I found that one, but once the plug was changed it worked fine.

try checking the battery voltage with it running, headlights on heater , etc and see, it should be between 13.5 and 14 is good,, have seen thought some GMs use a current sensor on the + battery lead, if you don't use a proper GM battery it messes with the sensor and the computer alt light... should be something like this on the + battery cable

Have you driven it at night to see if the headlights dim when this happens? Could be a simple loose wire between the alternator and the light or could be the alternator. Electric issues if random are hard to find sometimes. Does it do it all the time or when the road is rough. If you could have someone put a test light on something that gets electric from engine such as cigarette lighter when it was doing it, you could check output. You did not mention it but I am assuming it was not doing it when you took it in for service.

Disconnect the neg on the battery with it running if it stalls altanater is bad without the battery hooked up it should run if altanater is working.JMOP an sure others will disagree

For future info. There is NOTHING on a Motorhome that will tell you the battery is bad while driving. All it will tell you is the charging system has failed or there is a hiccup in the charging system and have it checked.
When this happens, do you have the GENSET running? When at the shop, can they duplicate the error on the dash or there is NEVER a flashing Battery indicator? I would suspect something downstream at the COACH Battery side. Something on the Coach and dual charging system is causing the Intermittant failure. Doug