E115 - I know this is an old thread, but I just ran into this code again. My experience on these units is that low voltage can throw most fault codes in the book. It's always worth starting with known good voltage. Unit would double click and fault to E115 when you tried any function or bringing the control head down to drive position. On one occasion, I was able to get the contactor to pull in and the horn to honk, but it sounded muted. I replaced the horn, and everything functioned as it should. I didn't dig any deeper to see if the horn had an internal short or...? Just thought I'd throw this out here, since it doesn't mention it as a possible cause in the book. You may also look at this thread for other causes: Raymond 102T-F45L
code 115 is there a fix.

Yes the computer wants to see good battery voltage on all 4 battery's l would not replace one battery as the other battery's will fail as all battery's are the same age