There is a wire from the starter battery to the EBL that powers the fridge 12V element. It also is used by the EBL/display to sense the starter battery voltage. Also the EBL uses it to charge the starter battery while on EHU. This wire has a 20A fuse near the starter battery. It's not the same wire as the main power to the EBL from the starter battery, which is thicker and normally has a 30A or 50A fuse.
The fact you have no engine battery volts on display suggests to me problem between engine battery and the ebl240. Have you diagram of the ebl240? If not will be on the schaudt de website. Any fuses on engine battery supply to ebl240? If so are they ok?
If similar to my van there are 2 wires from engine battery to ebl.
One to charge leisure battery, the other for fridge .
Sorry not familiar with ebl240.
Thanks for all suggestions. When I last had a charging problem, red light on dashboard staying on, it was a faulty relay on back of fridge which controls the 12 volt heating element. No idea why that has anything to do with the charging system but I think the charging and fridge faults may be related
In addition to the power two wires I mentioned, there is a third wire which is a control signal to indicate the engine is running and the alternator is charging. That's called the D+ signal, and it's produced by the alternator. It switches off the red charging light on the dashboard, and also controls things like the split charge relay and the fridge relay.
It is a 'signal', ie it is not meant to supply power, just a voltage indication. If too much power is drawn from it, the red light comes on. So if the faulty fridge relay was drawing too much power, that's why the red light was on.
I have a Schaudt LRM 1218 solar charger fitted which has 2 red wires coming out. One had come out and as it's not easily seen I only discovered it after deciding the fridge had nothing wrong with it and started at battery checking all connections
Thanks to Martin Bushnell at A & N Caravans for his invaluable advice