The most common motorhome problems solved

If a fridge is not working on gas (but is on 12V on mains), one possible problem is when the coating inside the burner feed pipe starts to flake off after a few years. Just one flake is enough to blow up into the gas jet and partially block it. The gas will still light and the flame may look OK, but it will not be sufficient to cause the fridge to operate correctly.

A burner dismantle should find the culprit, and, after cleaning all the bits and reassembling, normality should be returned. If you do this, then never force anything into the gas jet; it will become enlarged and your burner will quickly soot up.

On reassembly it should be checked by a qualified gas professional.

If a fridge does not work on 12V while the engine is running, it could be a problem with the feed from the vehicle battery and the alternator D+ terminal. This is the time to be using your digital multimeter.

With the meter set to DC volts and with the negative meter lead connected to vehicle chassis (battery negative), you need to measure the voltage at the point where the starter battery positive enters the EC500 and also where the alternator D+ connection enters the EC500. Both voltages should be around 14V when the engine is running.

There will quite likely be fuses associated with these supplies near the vehicle starter battery and these may be corroded. There are also fuses mounted in the remote EM40 interface unit, fuses six and eight being associated with fridge operation. Also check the four-way connectors for soundness of connection. These are the supplies used to power the fridge when driving.

If all is well, you probably need a replacement control PCB.

Most motorhomes use one of two kinds of water pump. Pressure-activated pumps are switched on when their pressure sensor detects a drop in water pressure when a tap is opened or the loo flushed. These are often external to the fresh water tank and the pressure sensor is adjustable.

They’re generally reliable but be aware that, if you have a water leak, they can activate automatically and pump water out of any hole or detached hose connector. Draining down over winter, and switching the water pump off when it’s not in use can prevent this.

The tell-tale sign of a water leak (or a failing water pump pressure switch) is if the pump keeps switching on and off when no taps are open. If a water pump does this, try adjusting the pressure valve to see if it stops the pump actuating. If it doesn’t and you’ve checked for any leakage, then suspect the pressure switch.

The other common type of water pump is one triggered by on/off microswitches located in each tap. These can be either mounted externally near the water tank or submersed in the tank itself.

Water pumps are generally reliable, but the microswitches on the taps can fail. If the water pump works on the kitchen tap, but not on the washroom basin, then it suggests the washroom tap has failed or has a wiring issue.

It’s easy to check if a microswitch tap works with a multimeter. Set the multimeter to its continuity setting and connect its probes to either end of the two wires coming out of the tap. If the meter doesn’t beep or indicate a connection when the tap is opened, the microswitch has failed and the tap will need replacing. Taps are generally easy to replace, but this depends on the access underneath them.

There could be a loose electrical connection to the pump as each time the pump starts it moves on its mounts and temporarily disconnects its 12V supply. As soon as it stops the pump moves back and the connections remake and that is how it continues. Check all the immediate and any nearby connections for cleanliness and tightness.

Many installations include a surge damper in the plumbing system to reduce the on-off frequency. The plastic retaining clip for the surge damper could be broken and the damper is laid on its side. The air comes out, it fills with water and becomes ineffective.

Motorhomes have two different batteries, the vehicle battery that powers the cab, starter motor and alternator (smart versions in many modern vehicles) and the leisure battery that provides juice for the appliances and lights in the motorhome itself.

Unless properly charged, both of these batteries can run out of power quite easily. You can top up by staying plugged into the mains, or use solar to trickle charge the system. It is worth checking how your charging routine is set up. Most systems will only provide a trickle charge to the engine battery once the leisure battery is fully topped up.

If you have space for a second motorhome leisure battery, though, you could double your amount of electrical independence with solar panels. There are limits on what a solar panel will deliver in winter with limited daylight hours.

Let’s say you fit solar panels rated at 120W. That is what you might get in midsummer at midday with a clear sky on the equator. In the UK midwinter, with limited daylight hours and mostly overcast, it’s another matter.

We would have no worries on panels rated 80W and above being able to sustain the load of a tracker during the winter.

If the charging system is fine, but the batteries keep discharging fully, then its worth doing some investigations – knowing where and what is drawing power is a particularly handy thing. If an appliance is drawing too much, then you can start to track down the problem.

It is also worth knowing that standard lead acid batteries fitted to motorhomes can only be 50% discharged before needing to be topped up. Lithium (LiFePO4) batteries have a much greater capacity to be discharged, allowing to you use more of the available power before being topped up. So if you want electrical independence away from mains hook-up, these batteries are a good option.

Airbag warning lights are a pain and seem to be more common in motorhomes. They can be caused by any fault, however temporary, originated by any device connected to the airbag control unit. These naturally include airbags, but also seatbelt pretensioners and seat occupation sensors.

Something as simple as moving the driver’s seat back or forward can disturb the wiring connections; and this is the most common cause of a warning light of this nature on any vehicle so equipped.

The airbag control module failing is a more common Fiat Ducato motorhome problem as it seems to be particularly sensitive to moisture, and this is more frequently found in motorhomes than in commercial vans.

The first thing to do would be to rule out anything completely obvious, so check for coolant leaks into the cab. If the matrix inside the heater unit is going to leak, it will deposit coolant straight onto the airbag unit, which is located behind the lower dash in the middle of the cab floor. If your coolant seems low and there is evidence of leaking on the floor, this will need to be sorted out.

Check under the seats for anything that has been stowed away and has come into contact with the wiring for the seatbelt pretensioners and sensors.

In most cases, though, getting the vehicle plugged into a diagnostic system that can read codes from the airbag system will provide at least clues as to what is wrong. You may see a particular device named and, initially, the wiring to that device would need to be checked before assuming that the device is faulty. They are often not.

If, on the other hand, the diagnostic unit cannot communicate with the control unit or it does but describes internal faults, then it will need to be repaired or replaced.

There are people out there advertising their ability to repair airbag control units, but the costs may end up being very similar to that of purchasing a new one and having it installed and programmed by a Fiat workshop. It will come with a warranty, too.