Technical Strange behaviours on starting

[kamiel kontrarie]

My Ducato is now a bit over two years old, with 57000 kms run. (yes, I'm from the Continent). It is a 3.0 litre and basically I am quite happy with it.

It has developed two strange habitudes, though, which weren't there originally, neither is really grave but it is a source of confusion. I don't think there is a relation between them but there might be.

1) when starting cold, i.e. after several hours' standing still, the engine starts very easily, runs at its normal 800 rpm for a couple of seconds, then goes up to some 1100-1200 rpm while sounding more rough. No change in indicator lights. After running/warming up for perhaps 10 minutes, the idle falls back to its normal 800 rpm

2) when starting, whether cold or warm, the "battery not charging" indicator comes up. I must then stop the engine and start it again, and everything comes to normal. Funniest of all: even with the indicator active, I measured 14.0 volts in the cigar plug so I fancy the battery IS being charged (didn't measure on the battery, as yet).

As I said, neither are really of concern but it would be nice to know what could be behind it, and perhaps what could be done about it. A mechanic I consulted about the second issue assigned it to cable damage by rodents - which I find hard to imagine, such damage would begin by showing intermittent issues, I should think.

I've not yet attached a diagnosis tool, no idea of the "error list" as it seems to be called.

 

[rayc]

Strange really as this ongoing topic reports and issue with the vehicle revving to 1200rpm on startup and battery lamp staying on.
https://www.fiatforum.com/ducato/358217-ducato-2-3-2008-lights-flicker.html

 

[CDK]

All warning lights on an X250 Ducato are controlled by a plastic box they call "chassis Computer", so it may very well be that the alternator is performing perfectly while the battery light is on. You can also have the bulb failure light on, yet when you walk around the vehicle everything works fine.

The fast idle command is related to the A/C unit, when it is switched on extra engine power is required and idle goes up just a little bit. But if the command is given while the compressor is not working, the rpm rises to approx. 1200.

There are 3 possible causes: wet connectors due to water ingress, rodent damage or a faulty chassis computer. The latter is not a structural component like the ECU, so less attention has been paid to reliability.
I regularly get a "low oil level" warning when starting. The first time this happened I opened the bonnet to check, now I just ignore it.

 

[kamiel kontrarie]

CDK, thanks. Any pointers as to the location of this plastic box?

 

[CDK]

The chassis or body computer is located under the dashboard in a compartment where also the diagnostics socket is.
Before you start digging, get a copy of the "eLearn" manual first because there is a lot of wiring involved. The box does all kinds of odd jobs, like imitating the clicking sound of the flasher relay and sending bus signals to nearly all electrical devices that used to have their own switch or relay in earlier models.
It even directly powers the lighter sockets on the dashboard. There are lots of fuses, but in my experience an output transistor is already blown long before the fuse does.

 

[kamiel kontrarie]

@CDK, many thanks!

And yes, it sounds not unexpected that fuses blow slower than semiconductors - the fuse is there to protect the wires, not the circuits.

PS would you perhaps have a pointer to this eLearn manual?

 

[rayc]

https://www.fiatforum.com/downloads.php?do=download&downloadid=381

There are also DVD versions on ebay