JLG 1250AJP Service Manual - Manual (Page 225)

SECTION 3 - 1CHASSIS & TURNTABLE
3121171 – JLG Lift – 3-177
SFC 512- Invalid Interrupt
Key On - Engine Running
System Data Mode
Clear System Fault
Does SFC 512 reset
with engine idling?
Fault is intermittent
Replace ECM with known
good part and retest
No
Check all power and
ground circuits to ECM
Are all circuits ok?
Repair wiring to
ECM and retest
Yes
Yes
No