Onan 5500 problem, won't start

[MetalGator]

Hello

Just picked up a new 2018 Miramar motorhome last week. The generator will not start from inside the coach. There is a switch on the dashboard, a switch in the bedroom and a switch in the middle of the coach to start the gen. When you take the cover off the generator outside, there is a switch where you can start the generator. If you hold that switch (primer?) a red light comes on but when you move the switch to the start position, it won't turn over. There are only 2 ways I have found to start the generator.

1) Before I took the coach home, the tech at the dealership showed me how to disconnect the control cable from the generator. If you do this, you can start the generator from OUTSIDE with the switch on the side of the gen.

2) By accident, I was looking in the battery compartment and noticed a 100 amp breaker on the batteries. If I disengage that breaker and then re-engage, the generator will suddenly start up! It scared me the first time since I wasn't expecting it. When the gen is started this way, I can go inside and look at the main panel (Firefly Multiplex panel) and see that the generator is running and see the hours meter incrementing. The gen switch on the dash will also be lit up. At this point, I can shut off the generator from all 3 locations inside. Once shut off, I can not start the generator again until I toggle the battery breaker or do #1 and start the gen from the outside switch while the control cable is unplugged.

The dealership couldn't figure out the problem and said they had spent time on the phone with Thor and Thor didn't know the problem. I have since spoken to the regional Thor rep (who has been very helpful) and he had someone call me. The Thor rep that called had me check some of the automatic gen start settings. I was at work at the time so couldn't try until I got home. I tried the settings and still no start. (Enabled AGS, setup the voltage settings, etc).

I have since received an email from the same Thor person that called and he said that I needed to take the motorhome to a local Onan repair shop. As you probably guessed, when looking up the local Onan repair shops in the area the dealership from where I purchased is listed (which they don't know how to fix).

Here is the direct quote from the Thor rep regarding the issue.

"If you disconnected the batter power for any reason, that could’ve blanked out the programming. You may just need to have a dealer set up the system again. It’s similar to the saved channels on your dash radio. When you disconnect the battery, you lose the channels. Same kind of thing here."

This is my first motorhome so I don't know if the above is true but if this is the case, wouldn't you need your generator "setup" again every time you changed your house batteries? I will add that the motorhome was delivered with dead house batteries. I believe this is because (another issue I need to get fixed) is the battery disconnect is either wired wrong or labeled wrong. When you put the switch is "use" mode, the batteries are disconnected. If you put the switch in "store" mode, the batteries ARE connected.

Anyway, does anyone have any ideas as to what could be causing this issue with the generator? It makes the AGS useless since the generator can't be started from inside and I don't want to wear out the battery breaker by having to toggle it every time I want to start the generator.

Thanks for any help or ideas.

Burch

[MetalGator]

One thing I forgot to mention is when I push the generator button on the main Multiplex panel, the subpanel in the bedroom, and the switch on the dash, I do hear a relay or something clicking in the back of the motorhome. Just no start.

[Chris_Bryant]

That is going to be a complex problem- not knowing the setup, electronics wise, it is hard to diagnose, but something is not right. Every brand of AGS I have dealt with has non-volatile memory- most rigs have battery disconnect switches, and nobody reprograms all of their electronics every time they use their rig.

For troubleshooting, I would try- if possible- disconnecting the AGS and trying it, then disconnecting the interior switch. But... if the whole thing is multiplexed, that really is not an option.

[MetalGator]

As a follow up, the tech at the dealer thought the inside controller was sending some type of "stop" signal to the generator which was keeping it from starting. This is probably why he tried disconnecting the cable from the generator. But I'm not sure this is the case sense I can start the gen (with the control cable plugged in) by toggling the 100 amp battery breaker. I had the gen running for a couple of hours this past weekend to run the 2 AC units while we were packing the motorhome.