New member needs an expert lol

[abmnw]

Hi all
Been a magazine subsciber for years but now need a little help please. Got a 2011 Autocruise Tempo (Ducato with 3l engine & Comfortmatic which may be relevent?) .
On our way to Portugal over the summer the battery light would come on at start up & after a couple of restarts would go out. When light came on step wouldn't auto retract. When we were in Lisbon took it to a Fiat dealer with the battery light off, they done a quick test & it was charging normally but recommended replacing alternator. Booked it in, got job done & away we went. Next day started van & light was on so drove it the 30 miles to dealer & they checked it again, this time with the light on & it was still charging normally. Also noticed that when light was on step didn't retract & fridge not working off the battery either.
It seems that the alternator when charging trips a relay or something that puts the battery light out, retracts the step & gives power to fridge. Garage cleaned connections, restarted it about 10 times & all good.
Assume you can guess what's coming next lol - yep next day light on but as we were starting our journey home & we knew it was charging we left it alone.
We spent a week coming back home & all the way up to Santander the light was intermittently on. Got off the ferry & the problem hasn't returned, that's over 8 weeks ago & we've covered over 1500 miles since then.
The question is, eventually lol, is it a relay that governs this, if so any idea where it is located as my feeling is that heat is affecting it as it has never happening in this country, it's a bit cooler than Spain & Portugal!

Sorry it's such a essay!

Thanks
Col

 

[LizziePope]

Hi there Col and a very warm welcome to the forum. I'll see if I can get an answer for you.

 

[TonyJones]

The auto-retraction of the step when you start the engine, and the 12v function of the fridge ARE governed by relays. Possibly the same one, as both are intended to kick in when (and only when) the alternator is providing a charging current. Since you're seeing both faults in conjunction with the no-charge warning light, "something" is telling both the light and the relay(s) that there's no charging current. I'd suspect the vehicle electronics, rather than the relay, but I'm no expert.
Lizzie, are you going to try DD ?

 

[abmnw]

Thanks for quick replies guys. When the fault occurs the alternator, which is new, is charging.
If all this is controlled by a relay my feeling is that the heat was causing it to stick? Do you reckon that's likely?
Col

 

[LizziePope]

Lizzie, are you going to try DD ?

Have done!

 

[LizziePope]

Hi there. I am pleased to say I've received a response from Practical Motorhome's technical expert, Diamond Dave:

"Alternator charging is controlled by the engine ECU on modern vehicles and the warning light on the dash will be controlled by a secondary computer called a BSI (Body Systems Interface). The step retract feature and fridge selecting 12V will often be controlled through a relay, which will generally be in a separate converter installed interface module often mounted at floor level behind the driver's seat. If the BSI doesn't switch the light off then the converter's interface doesn't trigger. The problem is likely to be in the BSI unit or its associated wiring, possibly a poor earth connection as they are the most common issues associated with electrical faults."

Hope that helps.

 

[abmnw]

Thanks all - sounds like a job for the dealer lol. If it had of been a relay I would have just replaced it but problem is I won't know if it's cured or not until I go somewhere hot!
Regards
Col