12v at car but not in van

The-colonel · Jun 23, 2014

Hi All,
I have all the necessary outputs from the car grey socket and all still live when I check the grey plug (tested by avo meter with outer cover removed) but when I check the fuse panel in the caravan there is no 12v input. One of the cables is the live from the grey lead and the other end of the fuse is a wire going to a relay, to that end I have no battery charging or lights or electronic cooker ignition with the grey socket plugged into the car, be it running or not! Is the relay at fault?
Advice appreciated
Regards Kenny

The-colonel · Jun 29, 2014

Changed the relay and although still getting power at the grey socket am not getting anything at the fuse box, any advice appreciated
Thanks Kenny

Damian · Jun 29, 2014

Is your van fitted with the NORDELETRONNICA power distribution system/?
#

The-colonel · Jun 29, 2014

How do I find out?

ApuljackEngineering · Jun 29, 2014

Where exactly are you measuring on the fuse board/what make model do you have?

Regards

Paul Wright
BSc MEng PGDip CEng MIET
Chartered Electronics Engineer

The-colonel · Jun 30, 2014

Hi Paul, across where the fuse would be. It is a 2004 Sterling Eccles Opal. For info across the fridge input where the fuse sits is the expected 13.84V
Thanks

ApuljackEngineering · Jun 30, 2014

Which fuse! Are you removing the fuse and then measuring across where it would be? What make/model of board do you have?

The-colonel · Jun 30, 2014

The top 20amp fuse and yes taking it out and measuring across the terminals. The fuse box does not have a make and I cannot see how I add a photo to a post. Your help is appreciated

colin-yorkshire · Jun 30, 2014

I think Paul is refering to the make and model of the charge unit!!! not the fuse, in order to post a photo you have to have a photobucket or similar account and post via a web link. see the sticky post here. http://www.practicalcaravan.com/forum/our-website/48966-how-to-photos

The-colonel · Jun 30, 2014

Oh! It is an ESM2004 combined unit located in the wardrobe
Thanks

ApuljackEngineering · Jun 30, 2014

Measuring across a fuse to determine voltage is not a reliable thing to do. You would measure across a fuse with an ammeter to measure current not voltage. If the load side that the fuse feeds is off then you would not measure a voltage. You should measure these pins relative to 0V/battery negative.

You should start by finding the cable that comes into the vehicle and making sure that the voltage is gettig to that and then tracing it through each unit/wire.

HTH

Paul

ProfJohnL · Jun 30, 2014

This thread is worrying me a bit. The OP tell us he has an AVO meter, yet he is trying to measure a voltage across a fuse carrier. Any person who has a reasonable knowledge of electrics or electronics would know how to interpret the result. The questions passed too-and-fro suggest there is a lack of knowledge.

Even though there is little risk of an electric shock from working with 12V dc, there is still a risk of fire from overheating if a wrong connection is made.

I think its about time the Colonel bit the bullet and gets a competent fitter to investigate and put it right.

colin-yorkshire · Jun 30, 2014

Sorry John I don't agree, the prospect of starting a fire by using a meter is almost laughable. the only thing the OP is doing wrong IMHO is by using both ends of the meter wires instead of one (red) while the other end (black) is attached to the return/earth, to find where the power is cut, Paul has this spot on, work from the plug (last known place there is power) "should be the green one from pin 4" and work backwards, doing the same from the battery (if fitted). there will be a place where the power stops. this will be where the fault is either a hidden fuse or the charge unit.
agreed the testing of voltage across a fuse is illogical unless one is testing the fuse itself but using a ammeter will confirm the current draw and the suitability of the fuse fitted.

The-colonel · Jun 30, 2014

Please let me clarify where I am with this to avoid the confusion I seem to have caused, I have tested the DC voltage at the caravan side of the grey plug when connected to the car and it reads 13.84V where it should, I have disconnected the cables at the fuse box inside the caravan and tested them and both still register 13.84V (that is into the caravan and the fridge circuit) When I reconnect them to the fuse box and start the car engine neither of them show any current being drawn across the fuse which indicates to me (and I am happy to be corrected) is that neither the battery charger or fridge is working on DC Power. Both however work on AC power. To that end is there anything else I need to check before getting a 'pro' in. I cannot see the 12V element behind the fridge and am unwilling to remove it as it involves gas pipes so cannot move forward with the fridge and the battery charger is internal to the power supply unit in the wardrobe as opposed to a separate unit (at least it looks that way without withdrawing the whole unit).
Any advice is gratefully appreciated.
Best regards Kenny.
PS I was using a multimeter not an AVO, apologies

colin-yorkshire · Jun 30, 2014

right got that, so there is power at the fuse when connected to the car, "but not when the engine is running!!" but none when it is running!!! have you tried testing the wire further back towards the car "where it enters the van" with and without the engine running as this would show a fault in the cars smart relay,
second the back of the fridge is accessible by removing the fridge vents, you should be able to see the 12v wire going into the fridge, ok, using the pointy bit of the red probe with the black probe connected to the return poke though the outer wire so the probe touches the inner cable, if there is power going to the fridge it will register a current even if the element is blown if no current it is not the element but the power feed.

The-colonel · Jun 30, 2014

Colin, no, there is 12.odd volts at the fuse box end of the cables with the engine off and 13.84 at the fuse box end with the engine on, that is how it is supposed to be I believe. When I then reconnect the cables to the fuse box there is still 13.84 volts but no amps being drawn by either circuit. There are two cables marked only for 12v which I can identify at the back of the fridge when I remove the grills but that is as far as I have got with it, a recent service the guy reckoned the 12v element could be at fault. Thanks for your post

Damian · Jun 30, 2014

You have now wasted over a week and got nowhere.

Although a service person has guessed that the 12v element has failed, without checking it , it is only a guess.

Get a mobile engineer out to look at it, all you are doing is confusing yourself and everyone trying to help you as you do not know what to look for or where to start identifying what Is wrong.

Sounds harsh I know, but give yourself a break and lessen the chances of a heart attack and get someone in to sort it out.

Find an engineer here: http://www.approvedworkshops.co.uk/search/

The-colonel · Jun 30, 2014

Damian, not harsh at all and sound advice which was my next step at this stage, thanks to all for the advice along the way
Regards Kenny

colin-yorkshire · Jun 30, 2014

fair enough Kenny, I think thats as far as we can go, let us know what the engineer does to sort it, although having dabbled in wiring systems for 30years and built numerious ones from scratch I would be very supprised if the fridge element was causing problems with other circuits there must other faults afoot.
hope it is not too expensive to rectify good luck mate!!.
colin

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12v at car but not in van

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