No power when switched to 'cab' and vehicle battery not charging (1 Viewer)

[RogerThat]

Soooo.....

You may remember last month when I started the engine with the EHU plugged in http://www.motorhomefun.co.uk/forum/threads/so-i-started-the-engine-with-the-ehu-plugged-in.140456/

Well, today I flipped the switch on the control panel to 'cab' and nothing happened. No lights, no 12v sockets, no volts showing on the little meter in the control panel, no nothing

Flipping the switch to 'hab' and everything springs in to life

My first thought was that little glass fuse in the EHU charger again, but that's checked out ok

If I plug the EHU cable in, everything works, all the lights and 12v sockets etc, BUT the vehicle battery is NOT receiving a charge (the hab battery DOES receive a charge when the switch on the control panel is in the hab position). So I know the charger itself is ok.

I've not started the van for a couple of weeks, so it's definitely not the 'human error' I made last time and the cab battery is actually charged, showing 12.6v on a multimeter.

I've checked every single fuse in the glove box, I've checked the four fuses under the wardrobe cupboard (where the EHU charger is), everything seems ok.

Where should I begin in trying to work out why I've no power when switched to 'cab'?!

Is there a big "MOHO" fuse in the engine bay perhaps? I'm suspecting there is as there are no volts coming in to the control panel and no charge going back out to the battery.

Can't get to the bonnet at the moment as I'm parked right up against the fence. Will roll it back tomorrow and have a poke around under the bonnet.

It's a 1999 Swift Sundance on a Ducato.

 

[RogerThat]

My control panel looks like this:

 

[glenn2926]

I'm not sure but I think you need the engine running for it to work on 12v. Not just switched to cab. Like when the fridge is on 12v it only works when the alternator is running.

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[pappajohn]

You are flicking the switch all the way ?

Center position is off completely and will only provide unregulated power from the charger to the 12v stuff when on hookup

If you are then there is a fuse somewhere between that switch and the engine battery which will have blown.
Location......could be anywhere but expect its near the battery to protect the associated wiring.

 

[SandraL]

my last van was 2005 fiat base with british conversion, under bonnet were 2 extra fuses. one fed fridge, step and leisure battery when engine was running. 2nd was permanently live feed from engine batt to control panel. These fuses were not part of fiat fuse boxes, but a seperate unit, on mine mounted above radiator on cross member. If yours is similar maybe check for live feed at the fuse feeding control panel.

 

[RogerThat]

I'm not sure but I think you need the engine running for it to work on 12v. Not just switched to cab. Like when the fridge is on 12v it only works when the alternator is running.

Hi, no, it definetly works (worked!) without the engine running.

You are flicking the switch all the way ?

could be anywhere but expect its near the battery to protect the associated wiring.

Hi, yup, switched all the way. I'm thinking a fuse under the bonnet somewhere too!

my last van was 2005 fiat base with british conversion, under bonnet were 2 extra fuses. one fed fridge, step and leisure battery when engine was running. 2nd was permanently live feed from engine batt to control panel. These fuses were not part of fiat fuse boxes, but a seperate unit, on mine mounted above radiator on cross member. If yours is similar maybe check for live feed at the fuse feeding control panel.

Good to know, this theory I see looking like the guilty suspect at the moment!

Will roll it back from the fence tomorrow and see if I can find an unusual fuse or two. I take it they are large sized fuses? Rather than a 'blade' fuse?

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[SandraL]

"Will roll it back from the fence tomorrow and see if I can find an unusual fuse or two. I take it they are large sized fuses? Rather than a 'blade' fuse?"


on mine they were standard 1/4" blade fuses rated at 20amps. There was an associated relay that operated when engine running (D+) for fridge etc.

 

[pappajohn]

As above....standard blade fuse.
Converters take the cheapest option and mega fuses are far from cheap.

 

[RogerThat]

Good to know what I'm looking for, thanks!

Re a relay, I hadn't paid much attention to it before, but there is a really next to the transformer/charger in the wardrobe. I might test this too just in case.

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[gus-lopez]

Good to know what I'm looking for, thanks!

Re a relay, I hadn't paid much attention to it before, but there is a really next to the transformer/charger in the wardrobe. I might test this too just in case.

I'd check that there is power switching over at the switch as well.

 

[RogerThat]

Bit of an update!

Rolled the MH back yesterday to get to the bonnet. Had a rummage around and sure enough, I found a couple of great big blade fuses and a relay. These were mounted ridiculously high up in the bulkhead. So high in fact that I couldn't actually get the fuse dust cover off! Nor could I get the relay out.

After much swearing, grazed knuckles, upside down contortionist impressions and some more grazed knuckles, I finally got them both out - this took the best part of 15 minutes, I kid you not.

And sods law, they were both fine!

So I put them back and as I did, the lights in the MH suddenly sprang in to action. Hmmm... Lose wire I thought, or dodgy connection. So I spent the next 10 minutes cleaning all the contacts on the fuse and relay pins. And things looked to be ok, till I closed the bonnet and the interior lights went out instantly!

WTF!

So I had another poke around and started wiggling all manner of wires that lead to and from this fuse and relay arrangement. SOMETHING was lose, I just couldn't find which wire it was.

Leaning back and sighing, I rested my hand on the van battery tray. As I did, I heard a faint little frizzy noise. HMMM!!!!

Rummaged around some more and would you believe, there are a few wires cable tied to the underside of the battery tray. These wires have a couple of quick release connectors on them. Wiggling these wires made the lights flicker like mad and also make some suitably concerning electrical crackling noises.

Thinking the connectors were possibly corroded I disconnected them and sets about cleaning the pins up. Pushed them back together again and it STILL didn't work.

Hmmm...

So I wiggled them some more and hey presto, one of the wires literally fell out the back of the connector!

And the wire has turned the most lovely shade of corroded-green you ever did see.

Happy that I've found the cause and with rain on the way, I taped up said weir, disconnected the EHU and disconnected the battery too - just in case!

So you can guess what I'll be doing at the weekend

Will post some pics of the guilty corroded connector(s) at the weekend too!

Blimey. Motorhomes, eh?

 

[RogerThat]

I'm pleased to say, all fixed

To bring some completeness to the thread, I'll show you some photos

Here's the fuse and relay that are literally touching the top of the bulkhead making it nigh on impossible to remove them. Why do they install things like this?!

I had to bend that entire metal bracket forwards by 45 degrees just to get the fuse out and even then the bloody wiper blade rods got in the way

So the other picture I wanted to share was of the corroded connector wiring.

Here's the connector(s) which were cable tied to the underside of the battery tray:

And here is a close up of the corroded wire which fell out the BACK of the connector, it's a lovely shade of green:

I wasn't sure if the corrosion had travelled down inside the copper wire but thankfully I only had to cut back about 10mm to reveal good wire:

Rather than just repair this single wire, I thought it would be safest to cut out the connector(s) on all three wires and repair/replace them too as it would probably only be a matter of time before they suffered the same fate.

All sorted this afternoon, I can plan the next adventure away now

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