LED on One Supply Is Off

If the LED on one power supply is off, but the LED on the other supply indicates that it is functioning properly, perform the following diagnostic procedure:

1. Check the red alarm LED on the craft interface:
   • If it is lit, issue the following CLI command for information about the cause of an alarm condition:
     user@host> show chassis alarms

     For a list of messages that can appear in the output, see Hardware and Interface Alarm Messages. A common cause of power supply shutdown is that the temperature of the power supply or another router component has exceed the maximum limit.

   • If the red alarm LED is not lit, check that the power switch is in the ON position on the power supply faceplate.
2. Replace the faulty power supply with a spare. For instructions, see Replace an AC Power Supply and Replace a DC Power Supply. If the LED lights correctly on the spare, the original power supply is faulty. Return it to Juniper Networks for replacement, as described in Return the Router or Its Components.
3. If the spare power supply also does not work, connect the router to a different power source. You might also try replacing the power cord (on an AC-powered router) or power cable (on a DC-powered router). For instructions, see Replace an AC Power Cord and Disconnect and Connect DC Power (you do not need to disconnect and reconnect the grounding cable on a DC-powered router).
4. If you cannot determine the cause of the problem or need additional assistance, see Juniper Networks Technical Assistance Center.

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