Alternator Help

[Floatymark]

Hi. My Liverpool NB has the Isuzu 35 with original HMI 70amp alternator running through a Sterling Alternator to Battery charger then onto 3 x 110ah agms. The leisure alternator has failed so I bought a Prestolite 90amp marine to replace with. Connected up but no output from the Sterling and lots of flashing leds. 
The new alternator is isolated ground where the original was earthed through the case. I’m guessing this is the issue. What do I need to do to get my new alternator working please? I’m at a loss. Thanks in advance. 

[Tracy D'arth]

Fit a ground connection cable from the alternator -B connection to an engine block bolt at least as thick as the +B cable. Sometimes you can take the insulating washer off the -B terminal and refitting the steel washer and nut will ground the terminal to the case converting the alternator to non-isolated.

[Floatymark]

Brilliant. Thanks Tracy. That’s much appreciated.