Technical D+ short curcuit. How to find the 2A fuse? 2021 Ducato

[Kosie5]

I have bought a 2021 ducato camper van and just realised that the leaisure battery is not charged when the engine is running. It is fitted with electro block EBL 119 together with a booster WA 121545. While trying to figure out if the EBL received the d+ signal I found the d+ wire for the booster squizzed underneath the seat baseplate. It has for sure made a short circuit to ground. After fixing the broken cable I still have no signal on the d+ wire at the EBL. I have gone through the fuses in the compartment fuse box with out finding any fuses blown. I can see in some wiring diagrams there should be a 2a fuse just “after” the alternator. Starter battery is charged at 13.8V.

Does any one have any clue where the d+ fuse is located?
Is there any easy way to find out if is 2A d+ fuse is blown or not? ( Engine symbol goes out on the dashboard when the engine is started.)

 

[MSjoberg]

I have bought a 2021 ducato camper van and just realised that the leaisure battery is not charged when the engine is running. It is fitted with electro block EBL 119 together with a booster WA 121545. While trying to figure out if the EBL received the d+ signal I found the d+ wire for the booster squizzed underneath the seat baseplate. It has for sure made a short circuit to ground. After fixing the broken cable I still have no signal on the d+ wire at the EBL. I have gone through the fuses in the compartment fuse box with out finding any fuses blown. I can see in some wiring diagrams there should be a 2a fuse just “after” the alternator. Starter battery is charged at 13.8V.

Does any one have any clue where the d+ fuse is located?
Is there any easy way to find out if is 2A d+ fuse is blown or not? ( Engine symbol goes out on the dashboard when the engine is started.)

This is a guess based on the 2018 model: If the EBL actually was fed with a +12 V signal for D+ (the "raw" signal from the ECU is not +12 V but "active ground") it might come from the Optional Wiring Control Unit (CCO) and Transformer Socket on the right side of the cab, at the bottom of pillar B. You can find info about this in the X290 Electrical circuits doc. under Downloads.

 

[Communicator]

I agree with @MSjoberg that the source may be from the optional connection panel. However as the source is active low, and limited to 300mA, the signal is often routed via a repeater relay module, of which the Schaudt DP02 is an example.

I have attached details of the connection panel. If this is not fitted then the alternator D+ connection to the Body Computer Module (BCM) is at pin 25 of the lower RH connector.

There is a lot of useful information in both the x250 training manual, and the converters and upfitters manual. Both of these are available in the "Downloads" section. See top of page.

 

[Kosie5]

I managed to find a blown 2A fuse. It was place just next to the EBL in between to relays. Under the drivers seat in a
left hand drive vehicle. I have my doubts that this is the D+ fuse I was looking for but now the leisure battery is charging and I also get an alarm when the electrical step I no retracted.

My guess is the fuse and relays are installed by Burstner together with the EBL

I looked in to the “pillar B” connection box and found very little. However one of the wire in the ”pillar B” is a D+ or “ignition on“ signal and also a low amp fuse. ( I only measured with the engine running so I am not sure if it is D+ or ignition). Could be useful information for somebody one day. I will use this signal later for a “auto retraction relay” for the electrical step.

Thanks to Msjoberg and Communicator for their fast suggestions.

 

[HughJampton]

I'd check again which wire is which. The "Converters Manual" for the slightly earlier x290 available as a download on the forum details the connections of the 15-way socket.

Whilst your picture isn't entirely clear, from the position of the connections it would appear that the socket might be "upside down" from the manual description. If so, that would make the red wire "ignition on" (positive with a maximum draw of 600mA) and the green one the D+. This latter is "open circuit" when the engine isn't running, and goes to ground when it is. This requires the converter to add a separate powered source and a fuse and relay (which the going to ground operates) to provide a substantial D+ signal to the EBL. The relay(s) and fuses in your other picture are probably providing this function.

I'm not going to swear I'm correct, as the picture isn't quite clear enough, and a vehicle as late as yours might have a different wiring schema, but the principle is likely to be the same, and if so, it is easy to test the two connections to determine which is which. If things are per the earlier X290 models, and you're getting 12v on the red connection with the engine running, then it's almost certain you've found the ignition-on signal, as the D+ would go to ground under those circumstances.

 

[rayc]

On my EBL 271 the D+ 'Negative when engine running' signal comes direct from the convertors socket i.e. not via a fuse. There is a switch on the EBL to select the D+ output to Haute [high] or Basse [low] to cater for the convertors requirement, which on my French Pilote is Basse [low] i.e. battery negative. The internal Convertor is a solid state chip which also acts as a buffer.
The ebl 119 does not have that facility. I have attached a link to the manual which has a schematic drawing. I am a little puzzled but is it looking for a D+ positive on block 2 / pin 3 with a corresponding positive D+ output on block 1 / pin 2? https://www.aandncaravanservices.co.uk/resources/Schaudt Elektroblock EBL 119.pdf

 

[HughJampton]

Ray,

I think the arrangements are very similar, but with one significant difference.

As above, the switching signal for D+ is conventionally supplied from the "Converters Socket", and Fiat implement this by sending a connection to ground when the engine is running (rather than delivering a +ve 12V signal).

Patently, this ground is of no use as a (12V) D+ signal, so it is generally used to switch an additional relay that has a permanent 12V input, thus effectively inverting the D+ signal and providing 12V with the engine running.

Admittedly, I've only taken a quick look at the EBL271, but it appears the circuitry to do that may be incorporated in the EBL (i.e. it will itself "invert" the signal).

On the EBL119 (and my EBL30) that is not the case. They expect a 12V signal as D+ input, so the "inversion" is carried out external to the EBL. Convertors may use their own system of relays/fuses to do this (and I expect that is the case here) or Schaudt will provide units (such as the AD01 used on my 'van) which will do this (and provide multiple D+ out, and other switched connections).

 

[rayc]

Ray,



Admittedly, I've only taken a quick look at the EBL271, but it appears the circuitry to do that may be incorporated in the EBL (i.e. it will itself "invert" the signal).

Hugh, it is interesting. The EBL 271 is switchable i.e. you can select it to be either high [positive] or low [negative] via the front panel switch. On my Pilote the signal from the convertors socket, which is annotated on Pilote drawings as ' D+ actif bas', goes directly into the EBL. For my systems to work the front panel switch must be set to 'D+ actif bas' i.e. it buffers it but does not invert it.
All external systems e.g. fridge, step retraction at start up etc use the negative D+ to switch them.

 

[HughJampton]

I have to say I disagree

I interpreted the circuit diagram as it containing the appropriate Fiat "inversion" (which must be done externally for the EBL119.)

The switch tells the EBL what "polarity" the incoming D+ signal is. When set to D+ Actif Bas, the EBL expects the switching input to go to ground when the engine is running (if set to the alternative, it expects an input +12V signal).

The extract from the EBL271 manual confirms:

I can only think the facility to switch is provided to support multiple base vehicles (e.g. MB will provide a +ve D+ signal).

 

[rayc]

I have to say I disagree

Hugh, Many thanks of course you are correct. Ray