Engine and generator won't run at same time

[weekend camp]

Hi, I have a 2003 Holiday Rambler Ambassador. When the engine is running and I start the generator, the alt. charge lite on my dash comes on and a buzzer sounds until I shut off the generator. This stops me from running my roof air while driving in hot weather. Does any one have a fix to my problem? Both work fine if only one is running.
Thanks, Charlie

[RV Mech Tech]

Charlie - what does the buzzer indicate - low fuel pressure or oil pressure etc? or is it a charging system indicator? - have you tried starting the engine when you are connected to shore power instead of the generator ? does the same thing happen? - the connection from the generator to the engine could possibly be through the coach battery charging system through a feedback that should be prevented by the battery isolater- I have worked on at least one class C and two class A's that would shut the generator off when the engine was started but those were fuel supply problems - when you have 120 volts coming into the coach the converter battery charger is activated and its possible that this may be feeding back into the vehicle charging system-

[weekend camp]

I have no idea what the buzzer indicates but the red lite is on for the charging system I'll head out know and try it on shore power get back to you I just went out and started the coach with the shore power plugged in no buzzer and no Alt charge lite every thing worked fine

[RV Mech Tech]

Charlie- have the generator checked for output - if both the coach and vehicle systems operate o.k. on shore power there may be something wrong with the electrical signal coming from the generator- there are basiclly three types of converters used in today's RV's- the 'Linear' , the 'Ferro-Resonant', and the latest 'Switchmode Electronic Converter' - all of these have different operating characteristics and can be affected by a to low or to high input voltage and in some cases the output of the converter may go above the maximum DC voltage if the AC input is to high (130 volts or more) such as in the Linear converter -since everything is o.k. on shore power I would look to the generator as the problem source first and have an output test done to confirm this - I would also check the operation of all the devices in the coach that operate on 120 V with the generator running and the engine off - if you have an energy management system check to see whats coming into the coach from the generator-let us know what you find-