X290 Hymer/Fiat electrical questions (1 Viewer)

[peterc10]

I have at last got round to dealing with the airbag warning light problem I have had for a while. The software that I bought for our son's computer reported the fault was in the Airbag ECU but could not clear it. So I have had to take it out and send it off to CrashData in Liverpool to recode. A lot cheaper than taking it to a Fiat professional dealer who will just fit a new ECU at an exorbitant price. During this a couple of things have crossed my mind.

Firstly, before removing the ECU I disconnected the engine battery's neutral connection as recommended by Crashdata,, to ensure that the airbags do not fire up when I disconnect the ECU. But whilst carrying out the work I accidentally switched on the crash flashers and they worked. How can they work when the engine battery is disconnected? My first thought was that Hymer had wired it to the leisure battery, so I switched off the EBL as well, but they still worked. So where are the flashers getting their power from?? And could it cause me a problem when I reconnect the Airbag ECU

Secondly I had to take off the low central consul with the cup holders to get at the nuts to remove the ECU. Whilst I have got it off I wonder whether I could install a couple of USB sockets in the removable piece at the top, as shown by the small rectangular gap on the photo below. I understand that later X290 models had one fitted in there as standard and I wonder where I could get that part. If not or if it is too expensive I can just drill a hole and fit an Ebay one. But I would like to use a permanent 12v supply rather than an ignition switched one. Is there any permanent live circuits I could pick up on in the vicinity, without throwing up Canbus alerts please? I can't pick up from the circuit for the two existing sockets just above because they are both ignition switched

Many thanks for any help.

 

[Stewart J]

USB I fitted a double usb as your thinking of doing, switched and fused directly from vehicle battery. Current draw when charging an iPad and phone simultaneously is minimal has worked well for over 3 years and no battery issues. And of course it does not infringe or cause canbus problems.

 

[Lenny HB]

But I would like to use a permanent 12v supply rather than an ignition switched one. Is there any permanent live circuits I could pick up on in the vicinity, without throwing up Canbus alerts please? I can't pick up from the circuit for the two existing sockets just above because they are both ignition switched

Just wire it back to the EBL so it runs off the leisure battery.

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[Larby]

I had similar problem with electric to ignition system and negative disconnected.
it was in the daytime. Solar panel sending some power?

 

[peterc10]

I had similar problem with electric to ignition system and negative disconnected.
it was in the daytime. Solar panel sending some power?

You may be on to something there. My solar panel supplies power to engine battery via the EBL, but I am still struggling to understand how that would work with the negative lead detached from the battery. Maybe it is being connected to negative via the hab battery? Maybe I should take that negative off?

I will check again after dark to see if that could be the case.

 

[peterc10]

USB I fitted a double usb as your thinking of doing, switched and fused directly from vehicle battery. Current draw when charging an iPad and phone simultaneously is minimal has worked well for over 3 years and no battery issues. And of course it does not infringe or cause canbus problems.View attachment 425474View attachment 425475

Thanks that is what I was looking for. Is that the original blanking plate you drilled a hole in or did you buy it with a plate and used that? What is the white stuff sticking out of the sides?

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[peterc10]

USB I fitted a double usb as your thinking of doing, switched and fused directly from vehicle battery. Current draw when charging an iPad and phone simultaneously is minimal has worked well for over 3 years and no battery issues. And of course it does not infringe or cause canbus problems.View attachment 425474View attachment 425475

Thanks that is what I was looking for. Is that the original blanking plate you drilled a hole in or did you buy it with a plate and used that? What is the white stuff sticking out of the sides?

Not sure how I double posted

 

[peterc10]

Just wire it back to the EBL so it runs off the leisure battery.

Trouble is can't see the route through from the cab battery to the leisure battery.

 

[Lenny HB]

Trouble is can't see the route through from the cab battery to the leisure battery.

Under the the cab floor covering, under the seat & down through the double floor.

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[Stewart J]

Thanks that is what I was looking for. Is that the original blanking plate you drilled a hole in or did you buy it with a plate and used that? What is the white stuff sticking out of the sides?

Not sure how I double posted

Original plate used a step drill, white stuff at sides is Blutac the lightweight clips on the blanking plate don’t secure it very well hence the Blutac, trimmed so now not visible. You can see the isolating switch I fitted in the photo, decided on vehicle battery rather than ebl as its such an easy short cable run, wired it onto spare small terminal and fitted an in-line 3 amp fuse at battery.

 

[Stewart J]

As Lenny said lead cable under the floor covering where it’s at its narrowest once you lift the battery cover it will become very apparent.

 

[Stewart J]

Apologies if I am causing confusion we are obviously cross posting.

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[Stewart J]

Step drill shown

in case your unsure, blanking plate is quite easily drilled as it’s not a hard plastic.

 

[peterc10]

Under the the cab floor covering, under the seat & down through the double floor.

Trouble is when I get there I have no spare circuits.

 

[Stewart J]

Guessing you are going the ebl route, use piggy back fuses to join into circuit at ebl obviously watch your fuse rating, something like this, you may find them cheaper and in less quantity.
https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=373054008129

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[Lenny HB]

Trouble is when I get there I have no spare circuits.

Which EBL have you got?

 

[Stealaway]

I fitted a three part panel there- also with voltmeters for monitoring both batteries

 

[TheBig1]

If fitting a USB charging port, look for a QC3, as these are compatible with modern phones and backwards with anything else. But charges at a much faster rate

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[peterc10]

Which EBL have you got?

EBL 29. Does it make any difference?

Guessing you are going the ebl route, use piggy back fuses to join into circuit at ebl obviously watch your fuse rating, something like this, you may find them cheaper and in less quantity.
https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=373054008129

Not sure yet which way, but at the moment I think it is easier to use the engine battery, which has a couple of spare connectors on it. In reality the solar and the EHU charge the engine battery as well via the EBL, so not sure it will make much difference. Doubt we will ever draw so much that the engine battery goes flat. The piggy back fuses you show won't work on the EBL as fuses are too close together in a line.

If fitting a USB charging port, look for a QC3, as these are compatible with modern phones and backwards with anything else. But charges at a much faster rate

Yep, I am getting a double QC3 thanks.

 

[Stewart J]

Peter I did the same with my previous van an Autotrail in over two years battery drain was not noticeable present van a Hymer 3.5 years and again no problems any drain is so small the solar takes care of it.

 

[Lenny HB]

EBL 29. Does it make any difference?

Only that I might have the info on it, I will have a look tomorrow.

Yep, I am getting a double QC3 thanks.

I wish they would keep up they are only 3 amps, my phone charges at 6 amps.

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[peterc10]

Thanks Lenny HB I have a wiring/block diagram but it is all like black magic to us civil engineers.

 

[Wissel]

Just a quick one on the airbag ECU.

One of the vans here had a problem, so last week I went to remove it to send off for repair.

I undid the 3 bolts first and could then see the wiring was loose. So refitted it and it works fine now. Just thought I'd say in case it works for you as well.

 

[peterc10]

Just a quick one on the airbag ECU.

One of the vans here had a problem, so last week I went to remove it to send off for repair.

I undid the 3 bolts first and could then see the wiring was loose. So refitted it and it works fine now. Just thought I'd say in case it works for you as well.

Unfortunately they were tightly clipped in

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[Lenny HB]

Thanks Lenny HB I have a wiring/block diagram but it is all like black magic to us civil engineers.

Look at the "Connector Assignment" page it will tell you what connections are spare on each block.
Should be some spare on one of the blocks that is permanently live & on a block switched by the control panel.

 

[tonyidle]

Firstly, before removing the ECU I disconnected the engine battery's neutral connection as recommended by Crashdata,, to ensure that the airbags do not fire up when I disconnect the ECU. But whilst carrying out the work I accidentally switched on the crash flashers and they worked. How can they work when the engine battery is disconnected

Unless you disconnect any power source that may be charging the engine battery you have not isolated the vehicle electronics and are working as though the engine battery was still connected. Motorhome converters don't make it easy because any vehicle and conversion connections tend not to be marked (or documented) but ensuring the vehicle really is isolated is important.

 

[Ditcha]

I purchased and fitted one of these no need for a on/ off switch as its built in works great.

https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=274433435058

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[peterc10]

I purchased and fitted one of these no need for a on/ off switch as its built in works great.

https://rover.ebay.com/rover/1/710-...0001&campid=5338547443&icep_item=274433435058

That is exactly what I bought, Though got it for more money from Amazon so I can get delivery tomorrow, as I want to put the dashboard back together again this weekend. That assumes that Royal Mail deliver my repaired Airbag ECU tomorrow as they are supposed to. And that the repair has worked!

 

[peterc10]

Thought I would update this and close it out by telling you what happened.

With regards to the live cab electrics it turns out that even if you disconnect the engine battery earth the engine electrics still remain live. And it is still live even if you disconnect the habitation battery earth. The only way to prevent this is by stopping all methods of charging, i.e. unplug the EHU and stop the solar. Rather than faff about with a ladder or disconnecting the solar I just waited until dark and unplugged the EHU to make my connections. Thanks for that idea Larby

The result is that my Airbag warning light now goes off when I switch the ignition on. Very good service from CrashData. I sent the Airbag ECU off to them Tuesday and it was back to me repaired on Friday. And a lot cheaper than the Fiat dealers who will just sell you a new one.

With regards to the USB sockets, I bought the unit that Ditcha linked to, which has a built in switch that kills the power. I decided it to run it off the habitation electrics because I can monitor the state of the hab batteries with my BM700, but not the engine battery. On my B678 there is no direct route to the floor gap from the back of the seats. However I eventually found a panel that I could remove to get there, but still involved some difficult threading. As it happened when I bought the Hymer I got the dealer to fit a 12v socket in the lounge area so I managed to tap into that feed so need to go as far as the Electrobloc. Now all done and all the bits put back.

Thanks everybody for all the help.