JLG 1500SJ Operator Manual - Manual (Page 105)

SECTION 5 - LCD DISPLAY PANEL - GENERATION 1 & 2
3121261 – JLG Lift – 5-9
CAN Communication Error Screen
The CAN Communication Error Screen appears if the JLG Control
System senses that the communication connection between the
LCD display and the Ground Control Module has been lost. In the
lower right hand corner, 66?? will display in the numeric fault
code area with a safety alert symbol. The actual code cannot be
displayed due to the communication error. Check the Service
Manual for the specific fault code. This screen will remain until
the condition is corrected.