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Motorhome advice – reversing sensors, gearbox repairs and more


The MMM team of technical experts are here again to help with your motorhomes and campervans problems. Here, they deal with reversing sensors, gearbox repairs, timing belts, solar panels, winter tyres for touring Europe, faulty motorhome blinds and more.

Does your motorhome or campervan have a problem that you need help with? Get in touch by emailing our experts at  [email protected]

Introducing the MMM Tech Help Team:

Nick Fisher – Tech Help Editor and Base vehicle expert
Peter Rosenthal – General advice
Clive Mott – Electrical expert
Mike Hill – Bodywork expert
Barry Norris – Technical & legal advice
Brian Kirby – All round expert
Andy Harris – TV & 12V expert


Do I need to rewire the reversing sensors on my Citroën-based campervan?

I own a Citroën Relay 2019 campervan and recently fitted a Witter towbar for a cycle carrier. The campervan came with towbar electrics already wired and it all works fine, but I have an issue that the reversing sensors are not disabled when the cycle carrier is fitted for use.

Looking at the campervan wiring, a bypass relay has been fitted, but I can’t see how this disables the sensors. Checking the main towbar dealer websites, it is recommended a dedicated wiring loom is used, which incorporates circuitry to disable the sensors. This would seem to be the answer to replace the existing wiring, but it’s an expensive option.

However, on reading the dedicated wiring loom instructions it has the standard bypass relay, but also requires a lead to be connected to pin 6 of the 8-pin connector of the factory-fitted Bosch Parking Assist module. I can see this to be the green/black wire, which apparently is the disable for the sensors.

Could I use this pin manually to disable the sensors via a switch? I don’t have any knowledge of what input is required or, if it is doable, is the Canbus involved?

Using a multimeter I think I have located the 12V supply to the 12-pin connector of the Parking Assist module, but could this be disconnected via a switch to disable sensors while towing?


A You just might already have the answer. Your vehicle should be fitted with a 13-pin trailer socket and the socket should include a microswitch, which is actuated when you connect the trailer plug and it turns off the reversing sensor alarm and, sometimes, also the rear fog lights. If you have a trailer board to hang across the back of your bikes then this should sort your problem.

If, however, you do not have a 13-pin socket with that microswitch then consider changing to one that does.

This automates the action you were suggesting to use a manual switch for. The Parking Assist module is a factory-fitted part and supplied exclusively to Fiat/PSA group. As it is Canbus-based, then disconnecting the 12V supply to the module would most likely throw up an error. As this is exclusively supplied, data is hard to find in the public domain.

I am advised by Witter that the manual switch or microswitch when operated should connect pin 6 of the Parking Assist module plug to chassis/negative to inhibit operation of the warning alarm.

However, I am also advised that this frequently causes warnings to be displayed on the dashboard and it is more of a nuisance than simply putting up with the noise. Hence, it does not normally connect it.
Clive Mott


Where can I get my gearbox repaired?

I have a petrol 2000-year Auto-Sleeper Symbol based on the Peugeot Boxer. It’s in good condition and been fully serviced, but there is a problem with the gearbox. I’ve been advised that the synchromesh has gone and that I should get the gearbox refurbished by a specialist garage.

I also need to get hold of a ‘front lower cross-member’, because the current one has some corrosion. Can you help?


A Parts for gearboxes of this age are becoming scarce, but there are a few items that gearbox specialists can get hold of. Do an internet search for gearbox specialists in your area.

If there are just a couple of items that are worn and, if there is just one synchromesh and (in all likelihood) one gear that is damaged, it might be worth getting just these replaced.

If there are more than two or three items worn, it is more cost-effective to get your gearbox fully reconditioned or to have a replacement box that has already been reconditioned. I would always advise that you get either option supplied by the garage.

The cross member is available from motor factors for a lot less than from Peugeot dealers. Whoever you get to look at the gearbox will be able to sort this out for you.
Nick Fisher


When should I replace the timing belt/chain?    

I have a Fiat Ducato, 2000 registered, 2.8idTD that has covered 50,000 miles with full service history and always had early oil changes. When is the time to get the timing belt/chain done? Also, is there anything else you recommend for a motorhome with this mileage?


A The 2.8idTD is, without doubt, my favourite Fiat engine. It was produced at a time just before things became overly complicated and engine designers were able to refine their products over time to improve efficiency without being hampered by the need to reduce the engine’s headline emissions.

By making an engine more efficient, and by burning less fuel, you get less emissions anyway! The 2.8-litre engine was developed from the 2.5-litre, over 15 or so years to be the cleanest running and lowest emission commercial engine available. It also pulled like a train and lasted forever if looked after properly.

So, how do we do this? Mainly by oil changes, so you are on the right track. Good-quality oil of the 15/40 variety. Every year or 9,000 miles will do fine.

I can’t remember the cambelt intervals and I have mislaid my book, but every four or five years rings a bell. At very low mileages, I would be tempted to extend that to six years, but not longer than that.

Lack of use puts the bearings in the tensioners through just as much stress as heavy use and these are far more likely to fail than the belt itself. Also, there are screws that need to be removed from covers to get to the belt and the longer you leave them, the more corrosion accumulates and the more likely they will be to snap when you try to remove them.

There are only two issues to keep an eye on with this vehicle.

The immobiliser unit is attached to the fuel pump at the front of the engine. This can, and will, fail but you will get a warning. The first time you find yourself cranking the engine over and it not starting while the immobiliser warning light stays lit, arrange to see an auto electrician. In most cases, you will get it to start after a few attempts, but the clock is ticking and you will be left stranded. Get it fixed.

I have also seen many of these engines where the coolant has become dark red in colour and the cab heater is working less well than it used to. I don’t know why these engines were more prone to corrosion in the engine block than those than came before or after, but they are and can normally be rectified with a decent coolant flush through with a hose and some new antifreeze.

Left unchecked, as stated, the heater will be less and less effective and localised blockages can cause engine overheating. Look for rusty red coolant and act sooner rather than later.

That’s it, really. There are very few sensors and considerably less wiring under the bonnet than the engines that followed, meaning far, far less to go wrong. Long may you enjoy it.
Nick Fisher


You can read more tech help content, and loads of practical motorhome and campervan advice, when you delve into our new content archive. Sign up, and you can read every article from MMM magazine, dating right back to January 2012. Start typing in 'tech help' into the search bar below:



Can I link my solar panel to the vehicle battery?

I have a 2020 Elddis Autoquest 185 with a roof-mounted 150W solar power panel fitted as standard that feeds the leisure battery only. The feed is through an LM series solar power intelligent PV controller, which presumably also limits the supply to avoid overcharging the leisure battery.

However, as a novice in the world of solar power systems and with an ever-flattening vehicle battery due to the installed alarm and tracker systems it seems to me that, at 150W, the solar panel should have enough potential to also supply power to the vehicle battery (Peugeot Boxer) and thus ensure both batteries are topped up.

Is this possible and, if so, are you able to provide information on what materials/parts I will need to install, plus an idiot’s step-by-step guide on how to modify/install my existing system to top up the vehicle battery and avoid overcharging?

I’m sure I’m not the only reader who would find this to be a useful guide given the lockdown and especially for keeping both batteries in top condition during Covid restrictions.


A Your 150 watts of solar real estate should be more than sufficient to maintain both your leisure and starter batteries while the motorhome is resting during this lockdown.

All solar regulators are designed so that they do not overcharge the battery. Your particular regulator will allow the charge voltage to go up to 14.4 or 14.6 volts for a maximum of one hour before reverting to the float charge voltage of 13.8V. As you know, your regulator is connected to charge the leisure battery, it is this charge you need to share.

A simple two or three-wire device sold as a Battery Master can be connected to link the two batteries together in an intelligent manner so that, once the leisure battery is charged, then some charge will be directed to the starter battery.

The three connections are the leisure battery positive, the starter battery positive and, for some, one of the battery negatives (chassis).

These connections are normally brought together where they enter the 12V electrical control box.

This saves longer wires to each battery, each with a fuse in for protection. The attached diagrams show the basic arrangement.

If you are not confident to follow this then get a qualified professional to install this kit for you. You will find such devices offered by Van Bitz  and from Votronic, sold by Roadpro which has a two-wire device.
Clive Mott


Can I repair the blind on my motorhome?

I have blinds/flyscreens that are in one piece (the blind comes down first followed by the flyscreens). One side requires retensioning while the other is more complicated, as one of the cords has parted from the top of the blind.

Is it possible to repair this or should I be looking to replace the whole unit?


A All blinds can be repaired if you’re prepared to do the work. Generally, you need to remove the outer frame (look for hidden screws under plastic covers or at the edges) by removing the corner sections. These often just clip on.

Looking at your particular blind, it looks like a Horrex-type as fitted to many Baileys. This is good news as replacements are available and they’re not that expensive at around £50 to £100 depending on size. O’Leary Motorhomes sells them as well as Just Caravan Parts.

Grab your screwdriver and have a look as a first step. With the frame removed you should be able to see the path of the string in the blind (have a look at a working blind to see the route it should take). Either the string has become detached from its mounting clips, or it has dropped off its plastic guide clips.

It might have snapped, but the string is pretty durable and it only tends to snap when it has become detached and is rubbing against something it shouldn’t. Often it’s that the plastic guides have become detached or have snapped with age – not pulling the blind down evenly with two hands or just pulling it down at one side can cause this.

I’ve not found anywhere selling individual components but, as Horrex is based in the Netherlands, where English is widely spoken, it’s worth getting in touch to see if it can help - go to horrex.nl/windows-blinds or call 0031102 619600.

If you can’t get spare parts (or if you have an older blind that is no longer supported with spares), then it’s worth knowing that you can get plastic moulding kits that allow you to mould your own parts. I’ve used Plastex (available on Amazon for around £30 a pack) to make unique plastic clips on classic cars and it works well. It’s an essential product to have if your motorhome or campervan is over 10 years old.
Peter Rosenthal


Do we need winter tyres for European touring?       

I need guidance on which type of tyre we should be running on our 2011 Bessacarr E520, which has been uprated to 3,850kg and has AirRide suspension.

Our tyres are currently Michelin Agilis 225/70 R15 CP 112Q and we change them around roughly every 5,000 miles to maximise wear and enable a full set of the same make/type being purchased when needed. We have travelled 99,000 miles and have used up quite a few sets of tyres!

Most have been CP-rated, but we did once use commercial-grade Vredestein van tyre. However, it was noted on our annual service and MOT as an advisory, that we were not using the correct tyres!

For clarification the Vredestein tyres were Comtrac All Season 225/70 R15 C with a load index of 112/100.

We travel around Europe (obviously not at the moment), through the Alps/Pyrenees, but also to the Mediterranean, meaning a large range of temperatures and, more importantly, road conditions, ie snow/ice through to tar melting!

What type of tyre should we be using for such a trip? My local tyre centre could not offer an all-season camper tyre.

There are commercial van tyre offerings with the snowflake (Continental All Season Contact, Michelin Cross Climate), but no CP-rated ones. I understand that it is illegal to use tyres without the snowflake during the winter months in Germany.

We have one more trip left assuming 5,000 miles with our current set, which we hopefully want to undertake in the spring, but what should we then purchase? The following trip will be in the autumn and, again, could result in all road conditions being encountered and many European countries being visited.


A I could go on for a very long time about ‘CP’ tyres and I made my mind up about them many years ago. Most of the justifications for CP tyres centre around claims such as ‘designed to resist heavier loads’ and ‘designed to resist ageing caused by UV light’.

The load-rating of the tyre is what determines its strength and suitability for a heavy load. A 112-rated CV tyre is the same as a 112-rated CP tyre. If you want to have an increased resistance to heavy loads, buy a 115 or 116-rated tyre. The ride might be a tiny bit firmer, but increasing the tyre pressures (which is not uncommon when comparing van and motorhome tyres) has the same effect.

As for the second claim, even if a manufacturer has incorporated a chemical into the casing material that resists UV ageing; the same manufacturer will state that the lifetime of a tyre is no more than six years and, even in the most extreme UV situations, this will not be seen very often within that time.

My advice is to consider a van tyre at the same or slightly higher load rating. Stay with reputable brands and save some money. The premium brands may last a little longer in terms of tread wear, but I have found through very extensive testing that some of the less-expensive semi-premium brands, such as Hankook, will last 80% of the mileage that a premium tyre might, but the slightly softer compound used (and the reason for the accelerated wear) can give better roadholding in a wider variety of conditions.

In light of the above, a tyre that meets the specifications and load rating should be acceptable.

That said, CP tyres are constantly improving and so, if your preference is for CP-rates tyres, there is a growing choice of quality CP tyres now available.

The Germans have rules regarding winter and all-season tyres, and also insist on the same make and model of tyre on each axle and they apply this year-round.

The compounds used in making winter tyres are soft in cold conditions, which is good in the winter, but they are too soft to run beyond winter conditions.

The compounds used in all-season tyres are designed to be softer than normal tyres in cooler conditions and as firm as normal tyres in warmer conditions. They may comply with the regulations but, in my experience, they are OK in most situations yet do not excel in any. I once drove a Fiat van with all-season tyres immediately after driving it with standard tyres and, yes, the all-season tyres were marginably better in the wet but, in dry conditions, I found they were inferior to normal tyres.

So, have another look at Vredestein all-season tyres. The brand has been making winter tyres for longer than most so it should know what it is doing.

I would look to see if it has a slightly higher load rating available and go for that if possible. You would then be complying with the rules in Europe. Always wait until you are in possession of an MoT certificate, but feel free to ask for justification for advisories.
Nick Fisher

Where can I source seats that convert to beds?

I'm going to convert another van into a motorhome and want to obtain a bench seat that can convert into a bed.

The idea is to install two bench seats opposite each other with the option of sliding out the inserts to make up a double bed. I have looked in my Auto-Trail motorhome to see if there is a manufacturer’s name on the frame, but there isn’t.

I could make one up, but the one fitted in my motorhome has a metal frame with wooden slats, which lift up so as you can get to items stored.


A There are dozens of these offered for sale on the internet – with both metal frames and wooden ones but, if it’s a specific Auto-Trail one you want, visit a motorhome breakers yard.

There are lots of firms fabricating this style of beds, too – for example, after a quick search we found Flatout Beds which may offer something that fits your needs and the space perfectly.

The only point to make with side settee beds is that they can’t be used for travel seats. Any sideways-facing belted seat should be avoided as they can cause horrible injuries.

So, if you need travel seats, they have to have three-point belts and must be facing forwards or rearwards with an M1 pull-tested frame (or TUV approved) and fitted professionally.
Peter Rosenthal


Should my inverter be wired through the vehicle’s RCD?

I have a 2012 Bessacarr E572 and had a 1,500W inverter fitted by a reputable installer. The first problem arose when using the inverter drawing off a pair of fairly new leisure batteries.

I discovered a 5A fuse in the inverter’s output plug and, needless to say, the fuse blew when I used the kettle so I swapped it to a 13A fuse and it’s been OK since.

I have also noticed that, when the inverter is in use, it continues to power the sockets even when the on-board RCDs are switched off. Is this installation as it should be?


A Your motorhome’s built-in RCD gives you protection against chassis/earth faults when you are connected to mains hook-up and covers all the mains appliances as well as the sockets.

When large inverters are fitted that supply the mains sockets then other fault scenarios exist and the output of the inverter should be passed through a second RCD to provide protection uniquely when using the inverter.

The inverter’s neutral output must also be connected to the vehicle chassis in order for the RCD to work. The same RCD can’t be used for both functions.

If you have separate inverter and priority switching unit then this is easy to implement. If you have an inverter with built-in switching then this becomes difficult as your inverter’s neutral bonding cannot be present when operating from real mains or the original RCD will trip out.

Some inverters have the neutral bonding point to a separate small terminal and, within the inverter, this connects before the changeover switching circuits so it does not connect the socket neutrals to the chassis when power is via the mains hook-up. Many inverters with built-in switching do not have this connection.

Combined inverters with built-in switching can turn off the inverter before operating the switching.

If you have a separate inverter and priority switching unit then the neutral bonding is easy to do. There are several priority switching units on offer, but most I have looked at are inadequately rated for the maximum voltage they could be required to withstand.

The peak voltage of a 230V AC sine wave is close to 320V and, depending on the phase relationship between the real mains and inverter mains when the real mains reappears, the voltage applied to the priority switching unit can be double this. 

A small inverter that has an isolated output and just one 13A socket into which you plug in just one appliance is deemed to be safe as the supply is not distributed to multiple places.

The factory fitted 1,800W inverter installation in our Hymer includes a separate RCD and a combined inverter with built-in switching and neutral bonding point.
Clive Mott


Can I source a replacement hob lid for my motorhome's kitchen?        

A while ago the glass cover on my hob shattered into a million pieces (a slight exaggeration). I have been unable to locate a replacement.

I have a 51-plate Bessacarr motorhome. The information on the inside of the cooker shows Stoves Mod No 0590510124 and See No 10405254.


A This is a tricky one! We couldn’t find any trace of this hob lid, either, so it’s possible that Stoves production of motorhome hobs was a short-lived thing.

The first place to try is Stoves itself to see if it has any new old-stock parts available. As it’s 19 years old, though, I think this is a long shot.

This leaves calling caravan and motorhome breakers in the hope that someone has one, but it’s just finding it!

Various firms can custom-make glass, but I’d rule this out due to cost. It would need to be custom-cut with radiused and polished edges, two holes drilled in it, then heat-treated and tinted. You could be into three figures.

One option is to use something like a sheet of stainless steel or aluminium. The issue is that these would have to be of a similar weight to the original glass for the hinges to work properly and you’d have to remember that they’d get hot in use. Plus, they’d look rubbish!

So that leaves two final options: put up with no lid; or replace the whole unit with a modern hob and glass unit. There are lots of reasonably priced hobs on the market and I’m sure you could get one to fit with just a little worktop trimming. This would also give you pristine clean burners and a working auto-ignition system.

Any local motorhome or campervan maker should be able to sort this for you. Maybe this could be claimed on your vehicle insurance.
Peter Rosenthal


What is the correct engine emissions standard, Euro 6 or Euro VI, for our campervan?

Can you set our minds at rest or resolve an issue with our V5C document regarding the emissions rating of our campervan? We took delivery of our Mercedes Sprinter L3H2 316 AWD-based campervan in February 2020. Having resolved various other issues with paperwork, we now have:

  • A Certificate of Compliance (CoC) from Mercedes, which records the engine as Euro VI D
  • An Individual Approval Certificate (IAC), which records the engine as Euro 6
  • A V5C from the DVLA, which records the engine as Euro 6.

We understand that, as the Mercedes Sprinter variant we have is a heavy-duty van (and required no changes or documentation to raise the Gross Vehicle Weight to four tonnes during the IAC process), it is assessed against different emission standards to those for light-duty vans.

What I cannot find guidance on, however, is whether the classification should be Euro VI (or even Euro VI D) on the V5C, rather than the current Euro 6. We’d be grateful for any help to clarify this.

Incidentally, I noticed an advert in the November MMM from Transport for London about heavy (over 3.5-tonne) diesel vehicles (and which refers to Euro VI engines) and the forthcoming Low Emission Zone standards coming into effect within Greater London, so the emissions rating must be important.

A In the past, the Euro status in numbers has been the appropriate standard for vehicles not exceeding 3.5 tonnes and the Euro standards shown in Roman numerals was used for heavy goods vehicles over 3.5 tonnes.

I now find from EC Regulation 595/2009 that, with the Euro VI standard, it applies to vehicles of categories M1 and M2 with a reference mass in excess of 2,610kg, which your motorhome is likely to be. Reference mass is defined as the mass in running order, less the notional driver mass of 75kg plus 100kg. It’s a strange figure as most other regulations including those relating to tax and driving licences refer to the up to 3.5-tonne and over 3.5-tonne limits.

How the DVLA works, however, is another matter. Checking my own V5C, I find the mass in service (similar to reference mass) box shown as 2,256kg, which you can probably appreciate is far too low for a 6.4m panel van conversion. From my weighbridge readings my reference mass or ‘in service mass’ is likely to be approaching 3,000kg and the 2,256kg figure is most probably the panel van prior to conversion.

That said, your main consideration must be that you have not misled the DVLA into recording false information on the V5C and also to ensure you are not unjustly penalised when entering a clean air zone and future zones proposed for other UK cities because of erroneous information on the V5C.

If you have supplied copies of the properly sourced CoC and IAC to the DVLA, then that’s for the DVLA to decide how to rate the vehicle. Presumably the DVLA is correctly showing the revised GVW of 4.0 tonnes and your VIN plate is also showing this figure.

It is most likely that a Euro VI rating for a vehicle over 3.5 tonnes would have permissible pollutant limits above a Euro 6 rating, although the testing regimes have been changing over the last few years. In practice for the purposes of the clean air zones, including LEZ and ULEZ (with tighter regulations starting 1 March), a classification of Euro 6 or Euro VI permits you entry into the zones without penalty.

You can check your vehicle using the checker on the LEZ website. Similarly, to check out the future clean air zones, use  gov.uk/guidance/driving-in-a-clean-air-zone
Barry Norris

Why are the fines different?

Upon returning from our French motorhome trip, I have received two speed violation notices. The first time ever in all my years of travel.

I do not understand why one is for €45, when I was doing 98km/h in a 90km/h limit and the other is for €90, when I was checked at 57km/h in a 50km/h limit.

Do different authorities in different parts of the country charge differently?

I was astonished to be caught speeding on the second one as I was fully aware of a speed trap in process and was being ultra careful.

A France has a national schedule of speeding offences with associated penalties which are published on the French government website under the section titled Vitesse au volant: la réglementation.

If you scroll down to: ‘Barème et sanctions en cas d’excès de vitesse’ (speeding schedules and penalties), you will see the penalty for exceeding a speed limit over 50km/h by not more than 20km/h is a fine of €68 and one point penalty.

The maximum penalty for exceeding the speed limit of 50km/h by less than 20km/h is €135 and one penalty point. Both your fines are within these limits and the norm is for the fines to be reduced to €45 and €90 respectively if paid within 15 days.

I understand the penalty points are not usually applied to non-French driving licence holders for the less severe infringements. 

Hence, it appears your fines are totally in line with this information.

The only variations across France I can think of in this situation are with regards to the implementation of the 80km/h limit, which came into force in 2018 to replace the 90km/h limit. This was implemented as a safety measure as a high proportion of French road crashes occurred on the 90km/h roads. However, this lower limit was not universally popular and so some departments have reinstated the 90km/h limit.
Barry Norris


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