I had similar issues, also sometimes error code 12 appears too. After check all my connections and finding out the lines were ok, I replaced the ECU and error code cleared out and equipment started.

Hello , does anyone fix this error 13 in screen? It says nu communication , is it possible the Volvo engine Ecm damage? It have battery voltage on connector.
I have the same issue in a DCE 100 forklift , no start activation
regards

well... hmmmm
either got a wrong or bad relay, put it in wrong place if they are different but have same plug socket, didnt plug in cables correctly or connected a wire to wrong place, damaged something in a connection... lots of possibilities here.

if you have access to diagnostic screen maybe check inputs and outputs , it may show you exactly where the problem is :o)

Someone took start relays out and starter then replaced them now the edu screens shows a code of 13 witch says in book check the cable from com to the edu truck doesn't even turn over

there should be more information other than 13 for the error code.
we need to know the node number it gives etc.

most of the codes i saw that have 13 all had to do with calibration but we need to know what needs calibration, the node number will determine this.

there is a big chance it is probably the accelerator but thats just a guess.

If you can get back to the truck and write down everything it shows when the error comes up that would be a huge help. ;o)