Technical Ducato 2008 X250 Motorhome - side marker lights switching on after cab doors are locked (after a minute’s delay)

[Bag E Puss]

Hi, I've had an occasional problem with this for a year, but for the last week the side marker lights have come on every time I lock the cab doors. I have a Dethleffs coach built Motorhome, but I think the problem is originating on the Fiat side. Here’s what I’ve found so far:

- Fiat remote keyfob will lock the doors, and lights come on after 1 minute. Fiat remote keyfob unlocks the doors and lights go off.
- Surprisingly, my Audi remote keyfob will also activate the lights, and deactivate them, but won’t lock/unlock the doors.
- I can hear what I assume is a Dethleffs installed relay clicking under the passenger’s seat whenever the lights switch on or off.
- Pulling the red fuse blade will deactivate the side marker lights and the relay (in photo).
- deactivating the Motorhome installed Schaudt Elektroblok EBL-99 (which controls habitation electrics) has no influence over the marker lights. The marker lights are on a separate circuit to the rest of the Motorhome electrics.
- turning sidelights on via the knurled wheel on the steering wheel stalk will turn the side marker lights on, and the relay clicks, even with ignition key out. Other side lights don’t come on.
- high level marker lights (red/white) are not impacted.

Am I right in assuming this is likely to be a fault in the CANBUS signal to activate lights, from which Motorhome builders take a feed (and use it to activate a side marker relay)? I understand that feed is via a plug in the drivers B-frame by the driver’s seat. I haven’t checked there yet.

What else can I do to isolate the fault? It is weird that the remote locking function responds to another manufacturer’s keyfob (at least in activating lights), which is why I am thinking this fault must originate in the Fiat CANBUS system.

Look forward to any advice.

 

[the green vanper]

I've just uploaded the Conversion and fitting-out manual for the x250 series. It's waiting for an approval. Once available, you'll probably be able to find useful and needed information to resolve your problem.

It should be available here:

x250: New Fiat Ducato. Conversion and fitting-out manual.

The original document prepared by Fiat Professionnal for builders / converters / upfitters dedicated for the Ducato x250 series.

www.fiatforum.com

First of all I'd check the ground points, especially the one behind the left headlight.

 

[Communicator]

Hi, I've had an occasional problem with this for a year, but for the last week the side marker lights have come on every time I lock the cab doors. I have a Dethleffs coach built Motorhome, but I think the problem is originating on the Fiat side. Here’s what I’ve found so far:

- Fiat remote keyfob will lock the doors, and lights come on after 1 minute. Fiat remote keyfob unlocks the doors and lights go off.
- Surprisingly, my Audi remote keyfob will also activate the lights, and deactivate them, but won’t lock/unlock the doors.
- I can hear what I assume is a Dethleffs installed relay clicking under the passenger’s seat whenever the lights switch on or off.
- Pulling the red fuse blade will deactivate the side marker lights and the relay (in photo).
- deactivating the Motorhome installed Schaudt Elektroblok EBL-99 (which controls habitation electrics) has no influence over the marker lights. The marker lights are on a separate circuit to the rest of the Motorhome electrics.
- turning sidelights on via the knurled wheel on the steering wheel stalk will turn the side marker lights on, and the relay clicks, even with ignition key out. Other side lights don’t come on.
- high level marker lights (red/white) are not impacted.

Am I right in assuming this is likely to be a fault in the CANBUS signal to activate lights, from which Motorhome builders take a feed (and use it to activate a side marker relay)? I understand that feed is via a plug in the drivers B-frame by the driver’s seat. I haven’t checked there yet.

What else can I do to isolate the fault? It is weird that the remote locking function responds to another manufacturer’s keyfob (at least in activating lights), which is why I am thinking this fault must originate in the Fiat CANBUS system.

Look forward to any advice.

If the base vehicle is fitted with a converters and upfitters panel at the base of the RH B pillar, the sidelights on signal could be obtained from pin 11 of the 15 way connector. Pin 11 is at the upper RH corner of the connector. The signal goes low (0V) with sidelights on. Output is quoted at 300mA max, and will probably control the relay that you can hear operating.

The sidelights on signal is supplied by the body computer and is located at pin1 (lower LH corner) of the 52 way connector when viewing the cab fusebox/ body computer assembly. As the body computer receives an input from the alarm receiver, I think that you may have to consider the possibility of a body computer fault.

 

[Bag E Puss]

Thank you all. I made a little progress. I managed to establish that the Motorhome conversion side is working fine, and that the signal at pin 11 in the 15 connector block (at the driver’s pillar) works as intended - it shorts to earth when the marker lights are called for by the Fiat electrics, and drives the relay in the Motorhome side correctly.

I also reset the vehicle management system by disconnecting the vehicle battery at both sides (following a protocol on another thread) but that didn’t help.

Bizarrely, I then cycled through my Audi remote key fob (unlock, lock, unlock, lock) which switched the lights off, on, off, off and the marker lights haven’t come on since.

I’ll address this all with Fiat Professional when my service visit comes up in a month and let you know what happened.

 

[Communicator]

Thank you all. I made a little progress. I managed to establish that the Motorhome conversion side is working fine, and that the signal at pin 11 in the 15 connector block (at the driver’s pillar) works as intended - it shorts to earth when the marker lights are called for by the Fiat electrics, and drives the relay in the Motorhome side correctly.

I also reset the vehicle management system by disconnecting the vehicle battery at both sides (following a protocol on another thread) but that didn’t help.

I do not understand the need to disconnect at both sides. What needs to be done is to make sure that other devices such as solar, or battery maintainer, are isolated so as not to provide a supply.

Bizarrely, I then cycled through my Audi remote key fob (unlock, lock, unlock, lock) which switched the lights off, on, off, off and the marker lights haven’t come on since.

I’ll address this all with Fiat Professional when my service visit comes up in a month and let you know what happened.

Please should we be reading "on" for the highlighted "off " above?

I suggest the following test, which does not seem to have been covered.

Unplug the 15 way connector.

Cycle the lock, and unlock commands with your Audi remote.

If the side marker lights turn on and off with the connector unplugged, then it would suggest the presence of another receiver being connected to the convertors wiring. Not a Fiat problem.

If the marker lights are not cycled by the Audi remote, then the problem is most probably originating in the BCM or code receiver of the base vehicle.

 

[Bag E Puss]

UPDATE: At the same time as the marker light problem, I have also had an issue with my wipers failing when on intermittent wipe - they operate for a few mins and then die completely. I then have to pull over and wait five mins before they start working again. Rinse and repeat. They work fine if I don’t attempt to use intermittent wipe.

Theses two issues seem to have gone and hand in terms of timing.

Two days ago, I replaced the wiper motor assembly.

I now find that this seems to have resolved all my problems and the wipers and the side marker lights now work fine. The only common feature is the body control computer. I wonder if has reset itself. Fiat have said “back feed” issues do happen.

The Motorhome is off to Fiat Professional tmw - I am interested to see what the fault codes and/or fault log looks like.

 

[Bag E Puss]

2nd UPDATE: Marker light fault returned while vehicle was at Fiat. Fault was traced to Body Control Module (Earth leakage inside) but Fiat no longer supply these. Luckily, I’d bought one of the right type from a breaker on eBay, but Fiat cannot reprogramme them. Off it will go to a 3rd party programmer to be cloned from the existing unit. All saved for a later date.

 

[the green vanper]

Check the forum for water ingress in the engine bay to prevent such things in the future.

 

[Communicator]

Check the forum for water ingress in the engine bay to prevent such things in the future.

Is not the BCM physically connected to the cab fusebox?

 

[Bag E Puss]

Is not the BCM physically connected to the cab fusebox?

Yes, that’s what Fiat Professional told me