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Fridge/12volt system

Richard J

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Hi All,

I am new on here, so apologies if this has already been asked.

I have a Swift 630L. My fridge has stopped working on 12volts and the 12volt system now stays on when the ignition is on(it should shut down while the engine is running). I am assuming these faults are related, perhaps a relay or similar.

Can anyone help ?


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...could well be wiring, fuse or relay fault on the D+ feed from the alternator.


This would feasibly affect both the fridge relay and the EMC relay (both using the same sensing).


Can you detail the full model and year of the vehicle and we can probably find a wiring diagram and give you some pointers.



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...you may well find the retractable step (if fitted) isn't working as well. (auto retract on engine on)


At a guess, the most relevant wiring diagram will be this:


http://www.sargentltd.co.uk/Swift_Motorhome_schematics_2005.pdf (first diagram)


Failure of the split charge relay (I should really say fridge relay), or the fridge fuse, could give the symptoms you have, as the EMC relay, which switches off 12V in travel uses the same feed.


Normally on Swifts of that age, these components are located under the (FIAT) black plastic cover to the top rear of the engine bay (2 nuts and lift off, from memory).


Check the fuses first (it should be no 2, with no 1 position non-populated - but there should be 3 fuses in a 4-fuse holder and it is best to check all.)


There should probably be two relays, and if the fuses check out OK, you could switch these over to see if the fridge one is dud.


Beyond this, things get a bit more difficult.





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Hi Richard,


You can find full wiring diagrams here Link


And the most likely place to start looking will be the double or triple fuseblock and relays located under bonnet. I believe in a Fiat it will be central at the back edge of the bonnet opening. Check each fuse and relay and every connection for signs of corrosion or poor connection such as burning.




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...from the labelling, I'm not sure the Lifestyle will have the Kontiki/Bessacarr wiring as in the 2004 version, and that the 2005 lower series diagrams may be more appropriate.


Nonetheless, we don't need to worry unduly unless the fuses/relays aren't the problem, as that part is common to both diagrams ;-)

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If the Fridge/EMC is not working but the habitation battery is getting a charge then the D+ and Alternator are probably working ok and the most likely cause is an issue with the Fridge driver Fuse or possibly, but less likely, the relay.


Check only one fuse at a time so there is no confusion about which one came from where. They should be different sizes, but not always the case.

The most likely problem is that the fuse in the Holder with the Red/Yellow wires running from it has failed or corroded. Suggest you renew it as a matter of course as corrosion can become an issue after a few years. Likewise suggest replacement of all these 3 fuses about every 7 years to reduce the risk of issues.


We would advise you don't 'clean' it as normal corrosion and emery paper reduces the thickness of the blade such that it can then become a poor fit giving future faults. This is especially a problem with cheap Chinese fuses that seem to start off undersize anyway. Only use a quality fuse.


If the fuse is replaced and the Fridge/EMC still isn't working, then try swapping the two relays. Mark them up first.

If the Fridge/EMC now works and the Charge to the habitation is lost, then it's the relay that was driving the fuseholder on the Red/Yellow wire.


Assuming the above fuses and relays check out ok and both Fridge/EMC, Charge and Step not operational it might be the Alternator or D+ driver.


Test the voltage at the Starter battery both before and after you start the engine.

Is the Ignition warning light also staying lit or flickering when the engine is running?

Does the Starter battery voltage go up to around 14v to 14.4v? If it doesn't, get an Auto Sparky to test the Alternator and it's D+.


If the Alternator has failed, suggest you replace the Habitation battery as the battery is normally the reason for the failure.




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...picture posting is a (reported) problem at the moment unless you are linking to them on a hosting site.


Hopefully, the fuses you've checked are those under the black Fiat cover at the rear centre of the engine compartment.


There should be two identical relays on a bracket next/near to these. You're interested in the functioning of the one that feeds fuse 2 (the fridge fuse) with a red/yellow output wire from the fusebox.


You can switch the two relays over to check the functioning (the other one controls the leisure battery charging from alternator).


If that fixes the fridge/EMC lighting problem then you have a duff relay, and should buy an equivalent of the one now working.


If that doesn't fix it, restore the relays to the original position, and, with a multimeter check the leisure battery voltage first with the engine off, and then with it running. It should rise with the engine running, and if it doesn't then you either have two duff relays (unlikely) or there is a fault in the D+ triggering circuit from the alternator to the relay(s).


The fuses/relays will look like the pictures in this thread:




...where there is some useful additional information.


If this doesn't identify the problem, things get a bit more messy.



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Thanks for all your help.

When you mentioned last night about the step, I guessed you were on the correct lines as I remembered the other day I left my deck shoes on the step while I put the motorhome up on the ramps. They got wedged, so blowing a fuse made sense. This morning when I checked the fuses I was in the wrong fuse box. Tonight I checked the correct fuses and replaced the blown one.

Everything is now working fine.

Thanks again for all your help. Cheers


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