E115 - I know this is an old thread, but I just ran into this code again. The troubleshooting below is correct and has fixed other units that we have. I went through those steps on this unit, even tested with new contactor and control relay since we have them in stock. Unit would double click and fault to E115 when you tried any function or bringing the control head down to drive position. 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.