Kevtwad
If this truck is equiped with a zappi combi controler it must have a BDI gauge on the Dash and if there is a fault with the truck then faullt codes will be displayed on the bdi in the frm of AL codes Like AL06 or AL17 but if you are referring to the flashing lights around the bdi gauge that end with a red ligfht at the bottom of the gauge then I would say you either had a battery problem or bad battery leads or a poor connection from the battery.
I would like to wish all members of this forum a happy new year and may you all have a good one.

Regards Titus