Resolved Coach lights up but doesn't turn when hitting ignition, generator won't do anything either.

[TheLooks]

If you have turned a battery disconnect relay(latching type) to the off position, you will not charge your house batteries on shore power and the lights etc will not work. These systems are not intuitive. There is a one way diode that allows the alternator on the engine to charge the house batteries while traveling, but the converter will not charge the chassis battery(s) while plugged into shore power. If the engine will not turn over, you have to look at the battery for the engine, not the house. Voltage will light up the gauges but you need amps to crank the motor. There should be a switch to (store) the unit, maybe called battery disconnect. There should be a button near the dash called Aux power, which uses the house batteries to boost the chassis(engine) battery to start.

 

[TheLooks]

You have to hold the Aux button in to use it, it will not click or stay on(momentary) contact. This ensures the 2 battery systems are not tied together unless boosting.

 

[Kuate]

Thanks all, yes correct on all stated.

A bit of history...
When I picked up the coach three weeks ago, I went camping and connected to shore to get familiar. Third night I couldn't start the coach, it was dead but it dimmed when trying to crank. I used the AUX Charge button (held it) to start the coach and charge the batteries. I made it home just fine and fired up the generator for two hours to see hot it performed with both AC's one (worked fine). Second night parked at home I noticed I again was losing power and managed start the coach again with AUX Charge. This was the original diagnosis that got me looking at charging the coach batteries with a battery charger/tender...and the rest went downhill after that.

The AUX Charge doesn't fire up the coach anymore even with new chassis batteries. I checked the voltage on the four house/coach batteries and they all showed 6.x volts. For now I'm just focusing on the chassis batteries 2 parallel 12 volts) to get it going again and not having much luck, Generator also doesn't do anything anymore.

I've picked up a few diagnostics tools to help me trace all the wires to try to find where I'm losing connection; they come in tomorrow (few meters and tone tracers). Someone in another forum mentioned a 200amp fuse but I have yet to find that.

Not quite feeling defeated yet the more I'm learning about the coach and troubleshooting (been eyeballing lots of videos and chasing forums). At first it was overwhelming but I think I'm getting close to finding my issue. Thanks ALL!

 

[TheLooks]

The Aux button also actuates a relay, which allows the amps to flow. Not sure if you mentioned it but I would question the quality of the batteries. Have them tested, not just checking voltage.

 

[Kuate]

The Aux button also actuates a relay, which allows the amps to flow. Not sure if you mentioned it but I would question the quality of the batteries. Have them tested, not just checking voltage.

Thanks. I replaced the batteries with two new ones two days ago and have the same result. I’ll try to head in later today to do more troubleshooting

 

[Kuate]

FIXED. It was one of the two for me below

Possibility 1
A stuck Intellisec BCC Relay. (Part 01-00055-00232798). There were two behind the Board by the batteries. I learned how to zap them open and close using a KZEEE KM10 (supplies 12v poles from battery). I disconnect coach and chassis batteries (for safety since I wasnt 100% what I was doing) and then zapped them to closed position. I started it up and it cranked I had read from someone else that posted similar process and believes they may have 'unstuck' the relay by giving it juice. However, not fully convinced this was it....


Possibility 2
User Error/Newness to the American Coach
While I had the BCC relay in front of me with disconnected batteries, I connected a wire toner (two piece gadget that helps you find wires via a tone wand) to the wire that zaps the BCC relay and had my wife find where it goes to the coach. Next to the slide control inside the cabinet was a battery disconnect that read AUX and MAIN (above it was the solar meter). This is where the buttons are to turn those relay on and off manually. It threw me off because everything I read calls these batteries Chassi/Motor, or House/Coach. After it started I then turned off the coach and played with these buttons and I was able to replicate the no crank no start. I may have turned those off while showing the coach to fam (or someone in fam did) because I thought those were related to the solar charging.


Finally, I'm leaning towards possibility 2 being my real issue because there was a key datapoint that kept getting overlooked when I was asking community for help (multiple forums). The coach not cranking, the generator not cranking, and the AUX Start not working anymore (all at the same time) all point to those two AUX and Main disconnect buttons. I'm happy it happened though because I was forced to learn a lot more about my coach than I expected to only three weeks in. I also feel that the battery tenders didn't do anything wrong and worked as expected, I went down a bunny trail because I thought i fried something. But now that I know what I know, the system is not really that complex from a regular vehicle. Still glad it all happened though. l feel better prepared for the road now given three weeks in to having my first motorcoach. Thanks to all the chimed in!