Em40 interface box

Suf wrote:Hello, 2018 warwick duo fails to switch from gas to battery and warning flashing triangle kicks in, we have switched back to electric

What fails to switch?  Your subtitle indicates you mean the fridge.
If it is like mine, I can't run the fridge from battery, 12V is from the engine alternator (when running).

Suf wrote:Where is the EM40 located please ?

Also the "EM40 Interface" on my 2017 Warwick Duo is on the top of the cabinet that houses the EC500 at the back of the van under the offside sofa. It does contain 2 20A fuses marked Fridge so I think  that's the place you should be looking.

It will only run on 12v with the engine running. Is it?

What fridge model is it? If it’s a Thetford N3000 series then it’s diagnostic system will flash a spanner symbol and a fault code on the display. The diagnostics and display are powered by the leisure battery so in the event of no power from the alternator, you’d still see a fault code.

Tim

I agree with Tim in that it would help to know which model of fridge you have e.g. mine has a Dometic RMS 8501 which does have a hidden service mode but I hesitate to talk about that any further as I don't think it is going to be the best solution here.

Maybe measure the voltage at the EM 40 ?  NB fridge has 2 12V supplies, one from the leisure supply for the control 12V and one for the heating element from the alternator.
I think if 12V is reaching the fridge heating element then it will need a repair i.e. something replacing. Is your van still under the 3 year warranty?

Applying first principles there are three possible fault conditions in the case of 12V operation. Either the fridge is not receiving 12V from the alternator via the EM40, or the “engine run” signal from the EM40 isn’t present at the fridge, or the 12V heater element in the fridge has failed. I’m surprised that a fridge on a 2018 van can’t be interrogated to help pinpoint the fault in the way that the Thetford does.

I can’t provide more specific help without knowing the specific model of fridge.

Tim

Geoff,

I downloaded the operating manual from Dometic’s website by entering the model number and selecting the 2017 version which would be pertinent to the age of your fridge.

The screenshot below shows the two faults that could occur to prevent 12V operation, which I’ve highlighted with red and green sidebars. Disregard what I said about the “engine run” (or D+)  signal as it only applies for fridges with auto selection of energy source and you said you think yours is manual. Incidentally you can easily confirm that: if you have a button marked “A” to the right of the battery selector button then you do have the AES version but if not then it’s MES. The screenshot shows the two cases.

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You’ve said the battery selector switch and warning triangle are both flashing, which confirms the diagnostic system is indicating a loss of 12V, which I’ve sidelined in red. At least that narrows down the fault to a single cause, so now the issue is where the 12V is being lost. More likely to be at a connector or fuseholder than a cable break. It was at this point that I remembered a similar issue earlier this year, and have found the relevant thread.

The forum is a rich resource and at this link [You must be registered and logged in to see this link.] you’ll be able to follow petermcd’s excellent fault diagnosis. You’ll see he had the same problem, loss of 12V but with a Thetford fridge. Thanks to Babian’s advice he traced it to the fridge connector on the back of the EM40 panel and found it was not making a good connection. I think he had to close up the individual female spade connectors in the socket that’s on the cables. I took a screenshot of petermcd’s picture and marked up the offending item in red below. Problems of this type with the EM40 (and 50) are reported elsewhere on here so it seems the most likely culprit.

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Let us know how you get on.

Tim

Ah good, at least you’ve identified the root of the problem. This is the 4th or 5th such occurrence I’ve read of on the forum in the past year, and the same connector (ie fridge) each time, whether on a EM40 or a EM50.

The overheating is almost certainly caused by a poorly fitting or poorly fabricated fridge connector, specifically the female part that fits onto the spades that are soldered onto the PCB. Arcing takes place which produces the heat, and the connector becomes compromised. In 12V mode the fridge possibly draws 10 amps or so, which can generate significant heat (proportional to the square of the current) if there’s excessive resistance in its path caused by a poor connection.

The thread linked below will enlighten you further. Although it concerns the EM50, it would seem the equivalent connector for the fridge is a problem there too. Read the posts by MelB and Marconi in particular.
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Reading that thread will hopefully help you in deciding how to proceed. You’ll know whether you’re competent to replace the connector and splice into the cabling. 12V installations seem innocuous because there’s no chance of being electrocuted, but the risk of localised heating (and ultimately fire) in higher current circuits remains. As you’ve seen, all it takes is one connector not performing as designed.

As for the parts supply, and whether the PCB has been damaged, I can’t say. A new EM40 is about £60 from Sargent, the manufacturer, but you’d still need to replace the female part of the connector.


Tim

Geoff,

Good plan, at least you’ve saved the cost of fault diagnosis. 

You’re right to be disappointed given it’s occurrence on other vans. The occurrences in the two threads I referred you to were on 2014 vans, the age of my van, which is why I’ve followed the story with interest. The fact that Sargent supply a replacement harness shows that the problem isn’t confined to just a few vans. Whether on a van converted in 2014 or 2018, it’s down to sloppy cable installation at AS. Sadly there are other examples reported here, such as poor termination of coax cable connectors.

Good luck with Spinny.

Tim

A faint buzzing noise as you describe could be caused by one of two things. Firstly, arcing at a loose connector or poorly fitting fuse holder, and secondly a faulty relay possibly.  

The problems reported further up this thread relate to a poor fitting fridge connector, which would only be apparent with the engine running, the fridge switched to 12V operation and therefore with current flowing through the connector from the vehicle alternator to the fridge. Your post doesn't mention whether this was the situation when you experienced the fault condition. If it wasn't, then I would suspect it was indeed a poorly seated fuse.

If the fuse in question wasn't an original as fitted by Sargent then it's possible it was replaced by an inferior version. I've learned from bitter experience that the cheap fuses from eBay can have thin blades which make for a loose fit in the holder. I now distrust any automotive fuse with a transparent plastic body and use only the solid coloured fuses from Sargent.

Tim

Doesn’t sound unreasonable. Good that you got it resolved, and at least you were able to do your own fault diagnosis and get ahead of the game!

Tim