It’s All Connected

Our products are front and center in many coaches. Consequently, we’re often the first phone call when owners experience problems with their coach, even when the problem has nothing to do with our products. That’s fine with us. There will be times when we have to refer them to someone else, but we do our best to help when we can.

Sometimes we encounter problems that leave coach owners – and often the techs helping them – absolutely flummoxed. It becomes even more complicated when one problem turns into several problems all at the same time. But all of those seemingly unrelated problems often stem from one common source. I encountered such a case today.

The owner had been dry camping for a while and noticed that her stove wouldn’t turn on. She checked the usual suspects – breakers and GFI’s. Nothing wrong with those. She also noticed that her living room was getting pretty warm. She had set the temperature to a brisk 68 degrees, but in the desert heat, the rooftop unit definitely wasn’t keeping up. The temperature had drifted up past 80 degrees. The bedroom was nice and cool, though. It was when she noticed an error message on her Silverleaf control panel that she decided to give us a call.

Over the course of our conversation, we uncovered more problems. Not only were the air conditioners and the stove misbehaving, but the inverters weren’t switching to Standby, even though the generator was running. The batteries had dropped to just over twelve volts, which meant the inverters weren’t charging them. Also, the gray tank, which was about half full, was reading empty. With this many problems at once, I needed to separate them first; divide and conquer. We started by checking the settings at the control panel since a climate control problem could easily be caused by an incorrect setting. Nothing to see there. They were all correctly set. Next, we checked the diagnostic screen. No clues there either. So I decided to go with my gut.

Given the age of the coach, I had a hunch that the floor heat controller had failed. When this happens, they have a tendency to disrupt other unrelated heating and cooling functions. Sure enough, checking the network census showed a TM229 floor heat controller that had lost its mind and was masquerading as a TM220. Problem solved, right? Well . . . no. Not even close. The TM229 might explain why the air conditioners weren’t working, but it didn’t explain any of the other problems. And, as it turns out, unplugging the TM229, and thus removing any influence it might have had on the rest of the coach, proved that it actually had nothing to do with the cooling problem. We were no closer to solving this riddle. While a lesser tech would have given up at this point, a greater tech would have known exactly what the Comm Error message on the control panel meant. Fortunately, my perfectly balanced mediocrity meant that I had an interesting challenge before me that I would eventually unravel.

I decided to chase down the next obvious lead. The TM102 is solely responsible for reporting tank levels. Since the gray tank level was obviously incorrect, I decided to check other data reported by that same module. Sure enough, all of the transfer switch data was missing. The original transfer switch in this coach relied on the TM102 to translate the data into a usable format called RV-C. Checking the TM102 revealed that it was happy and healthy, so I turned my attention to the transfer switch itself. It had been replaced with a newer model with its own RV-C connection, which meant that the TM102 did not need to interpret. But the transfer switch had both the new communication line connected to the RV-C network and the old line going to the TM102. Odd. . . Checking the TM102 again, the extra cable was not plugged in at that end. Aha! That must be it! Well, it wasn’t, but I was on the right track.

I finally had enough insight to put the pieces of the puzzle together. Maybe the stove wasn’t the only appliance that had lost power. I asked the owner to check the other appliances. As I suspected, the refrigerator had also lost power. I had seen enough. And now the great Hercule Poirot was prepared to reveal the identity of the killer. Yes, the Comm Error on the touch panel meant that the transfer switch had lost communication, but it wasn’t a simple matter of missing data. The transfer switch had failed outright. It was no longer transferring power from the generator. This meant that the inverter had no incoming voltage for charging the batteries, hence the battery voltages were lower than expected. It also meant that there was no voltage to pass through to the house circuits, hence the stove and other appliances were inoperable. It ALSO ALSO meant that the air conditioners wouldn’t function normally because only one of them can be powered by the second inverter. This coach needed a new transfer switch. Mystery solved.

In the end, the failed floor heat controller and missing gray tank level were red herrings, no doubt orchestrated by some devious RV gremlins in an effort to mislead me. I suppose the point of this story is that sometimes the manifold problems that make us want to pull out our hair can be traced back to a single solution. Often, all it takes to reclaim our sanity is a good tech – or, in this case, a splendidly mediocre one. Either way, even if the issue turns out to be completely unrelated to our products, we’re glad to help.