Apple ColorLaserWriter 12/600PS - Manual (Page 353)

Problem with internal random-access memory (RAM)
The printer does self-diagnostic tests each time it is turned on. During this
testing, the printer verifies the amount of memory installed. If the test
determines that a SIMM is faulty, specific status panel lights come on.
If you have just installed additional RAM, open the printer and make sure the
SIMMs are fully seated in the correct sockets that match one of the supported
configurations listed in Chapter 5 (and in Appendix A). Try reinstalling the
SIMMs, following the instructions in Chapter 5.
If this does not resolve the problem, contact an Apple-authorized service
provider.
M C
Y Bk
!
Cyan toner light on One light on means the SIMM in J11 is faulty.
Two lights means the SIMM in J10 is faulty.
Paper Out and Paper Jam lights blinking
333 Diagnosing Problems for Service