Chapter 4 Troubleshooting the Installation
Problem Solving with Subsystems
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Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
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Step 7 If a spare PEM is available, replace the existing module with the spare. If the
OUTPUT OK LED then goes on, the PEM is working normally.
Return the faulty PEM for replacement.
If you are unable to resolve the problem or if you determine that either the PEM
or power wiring is faulty, contact a service representative for assistance.
Troubleshooting the Processor Subsystem
The Cisco 12006 and Cisco 12406 Router processor subsystem consists of the RP,
the line cards, and the alarm cards. The RP and the line cards each have two
processors. One processor is the main processor; the other processor is a
component in the MBus module. The MBus module begins operation as soon as
power is applied to the system. The MBus module determines the type of card it
is mounted on and whether it should turn on the DC-DC converter. The RP MBus
module turns on card power after a brief delay; the line card MBus modules delay
turning on power until they receive a command from the RP.
A Cisco 12006 and Cisco 12406 Router requires that one RP be installed, or the
system cannot operate. A line card that is partially connected to the backplane will
send incomplete signals to the RP, which could cause the system to hang. Line
cards should be completely installed and seated in the backplane connector, or
fully removed and placed in a protective ESD device. If necessary, you can
troubleshoot individual line cards, but first ensure that the RP is installed properly
and the system software has initialized successfully.
A power-on self-test (POST) runs immediately at power-on to determine the
condition of the RP memory. Results are displayed in the alphanumeric LED
display as a pass/fail message.

Troubleshooting the RP

Check the following to help isolate a problem with the RP:
• Both the alphanumeric LED displays are on.
The two displays are powered separately. The left display receives power
from the DC-DC converter on the RP. The right display is powered directly
from the power supply. If the RP is not powered up, its right display may be