Is there a fuse I can pull during towing to reduce battery usage?
Tim Nieto, Reno, Nevada
Tim, since the 2003 Sonoma was not among the vehicles approved for flat towing, a lot depends on how your GMC was wired for towing and, of course, what type of onboard equipment you are using; i.e., auxiliary braking device, lube pump, etc. If all the power for the towed vehicle’s turn signals, stop lamps, and running lights originate with the motorhome, as they should, and no onboard power is required by the pickup, then the simplest method would be to install a battery disconnect switch for all circuits contained in the truck. This can be accomplished with a simple knife-blade manual switch or a sophisticated electronic solenoid mounted near and connected to the battery on the truck. Both are available at any well-stocked RV accessory store. Either device will enable you to fully disconnect the truck battery while towing.
I do recommend breaking the circuit on the ground side. However, it’s possible there is a drain on the battery caused by the tow wiring. The turn signals and taillights require diodes to prohibit crossover, current draining, or bleeding while towing. Without seeing the wiring or the methods employed, as it stands right now, I’d only be guessing. I’d recommend a trip to your local RV service center to check out the existing wiring configuration and possibly have that bothersome drain eliminated. I’d hesitate removing any fuse until it can be ascertained that the circuit protected by that fuse is not required by the truck while towing.
No output “” generator
Dear RV Doctor:
I have a Generac gasoline generator in my motorhome. I started it up and it was running fine for about five minutes. Then it stopped putting out any electricity, but the engine continued to run fine. The 20-amp circuit breaker on the unit had tripped. I reset it but still had no output. I have checked both circuit breakers with an ohmmeter, and I detected resistance in the closed position and none in the open position. I checked all the breakers in the coach, and they seem fine. Could the problem be farther down the line? What is a “J-box”? Any idea what else I should check?
Karle Meyer, Littleton, North Carolina
Karle, if you are sure the circuit breakers are okay, then there might be something more serious to contend with internal to the generator. First, with the generator running, check for AC voltage at the input to the circuit breakers. This will rule out the breakers and anything downstream. If there is no voltage, or lower than normal voltage, going into the circuit breakers, then the problem is likely a bad voltage regulator, rotor, or stator in the generator itself. All of these components are very expensive and difficult to replace, and they mandate you take the coach to a qualified Generac dealer or service center for repair.
Also check the voltage at the output of the circuit breaker. If there is voltage at the input to the breaker but not the output, then the breaker is faulty, even though it passed your continuity test. It may break down under current flow and/or higher temperatures.
The J-box you referred to is the junction box. It is located fairly close to the generator (upper right in the photo) and is the transition connection between the flexible cable coming out of the generator and the conduit going into the motorhome. If AC voltage is present at the output of the breakers, the next place to check is inside the junction box. Remove the cover and inspect and probe the wiring. If power is detected there, then the problem is farther downstream of that.
You did not mention whether you have to manually plug your shore power cable into a generator receptacle or whether you have an automatic transfer switch. If you have a transfer switch, that is likely to be the problem if the rest of the areas check out okay.
No output “” water heater
Dear RV Doctor:
I am having problems with my RV’s water heater, which is both gas and electric. The tank fills up and the water gets hot, but when I turn on the hot water at any faucet, all I get is cold water. I checked the valve and it is open on the water heater. There are three valves: one is the cold water feed; one is for hot water; and there is another pipe that runs between the cold water pipe and the hot water pipe. When I turn this valve off, I get hot water for a second or two and then I lose all pressure and nothing comes out. But when I turn this valve back on, I get water pressure, but only cold water. Any ideas?
Gerald Ward, Mansfield, Ohio
Gerald, this appears to be a problem with those hot water bypass valves. The pipe that runs between the hot and cold water lines is there to put the water heater in bypass mode for winterizing. It allows the antifreeze to cross over from the cold water lines to the hot water lines without filling the water heater tank. This valve (see arrow in photo) must remain closed for normal operation. It is open only for winterizing when the other two valves are closed. Since the hot water outlet is at the top of the water heater, you won’t get any pressure in the hot water line unless the water heater is completely full. You mentioned that the water tank fills up, but I suspect it may not be completely full when you are checking it. Make sure the valves on the cold inlet and hot outlet are totally open and that the crossover pipe valve is fully closed. The water heater can then fill normally. It can take quite awhile for the water heater to fill up completely. You’ll know it’s full if you have water emitting from the pressure and temperature (P&T) relief valve on the front of the water heater.
Once water flows freely from the P&T valve, begin opening the hot faucets one at a time. It will take a few minutes to purge all the air out of the lines. Once water is flowing freely from every hot faucet, light the water heater or turn on the heating element. After the water heater cycles off, you should have hot water at each hot faucet as soon as the cold water clears. This could take a few minutes of running the hot faucet.
If you still do not have hot water flowing through the system, there could be a blockage in the water heater or one of the fittings, or kinked tubing coming out of the heater, and further troubleshooting will be in order. It’s also possible that the center crossover valve is faulty “” not truly closed even though the handle indicates it is closed. If you have plastic bypass valves, it might be a good idea to upgrade to more substantial brass valves.
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