Technical Battery light on but charging

[John Brunning]

2020 Ducato battery light came on whilst in Spain everything seems to be working fine checked charging 13.4 it drove home from Spain with no problems but light comes back on after a couple of minutes driving. I've checked all connections all clean and tight. Code reader comes up code U0413- 87 any help would be great

 

[rayc]

I believe the D+ signal from the alternator switches the lamp off when the alternator is running. [ the D+ signal that motorhome convertors use for fridge switching on 12v, step retraction on engine start up etc. is also derived from this source.] On the attached drawing A010 is the alternator, D+ provides an input into M001 the body computer module which operates the lamp in E050 the display panel.
This applied to the non stop start / smart alternator models. It is different if stop start / smart alternator is fitted, U0413 code is I believe the code for invalid data received from the battery energy control module so smart alternator model