179 heater issue

Hello guys/gals
Out camping in our 179 for the second time and after our first trip the pod went to the dealer for a electrical water heater issue. The problem was it would blow the breaker but we did fine just running it in propane mode. The dealer said they couldn't find anything wrong and in fact now the heater no longer "pops" the breaker. However now the propane mode wont work. It is getting propane, I can manually light it but it only stays lit for a few seconds. What isn't working is the automatic ignightor and I suspect this is why it shuts down right after lighting. Any ideas?

Probably didn't explain it well enough. When you flip the inside switch you hear the gas valve open, propane flows but the ignightor doesn't fire. To check propane flow, I first blead the line at the heater (unit had been off and in storage for 7 months so I wanted to purge the air out). I then flipped the switch and noticed no clicking sound of an ignightor. I then manually lit the tank and it completely fired for about a 3 count but then would shut off. My guess is there is something wrong with the ignightor which is causing the tank to shut off the gas feed? I have checked the fuse box but all are good.

Yeah, looked for a web first,nada then purged the line. If you take a lighter and place the flame in the open space next to the exit point for the gas line you can manually light the unit. What I'm trying to recall, isn't there suposed to be a clicking sound coming from the ignightor? Mine isnt making that, I'm wondering if there's a "safety " device that if the ignightor doesn't fire does the system shut off the gas? This appears to be what's going on. So what I trying to figure is why isn't the ignightor firing? Anyone had this issue?

Thanks for the replies. The water was cold when I discovered I had a problem and I  probably should have mentioned that the DSI fault light does come on after the 3rd try. I'm convinced there's something wrong with the ignitor as you can hear the gas valve open and propane flow for the 3 count but then the valve shuts off.  I did run the short trip by flipping the elect switch and heating the water with the Honda 2000i. Frustrating. 

It's a water heater issue. Heartland has a pretty good troubleshooting guide, LP issues start on page 11, is viewable here:

https://manuals.heartlandowners.org/manuals/Troubleshooting%20Guides%20and%20Tips/Water%20Heater%20Troubleshooting%20-%20Suburban%20V1.3.pdf