HP ProDesk 400 G2.5 Maintenance And Service Manual page 111

NOTE: If you see flashing LEDs on a PS/2 keyboard, look for flashing LEDs on the front panel of the
computer and refer to the following table to determine the front panel LED codes.
Recommended actions in the following table are listed in the order in which they should be performed.
Not all diagnostic lights and audible codes are available on all models.
Activity
White Power LED On.
White Power LED flashes every
two seconds.
Red Power LED flashes two
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
Red Power LED flashes three
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
Red Power LED flashes four
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
Red Power LED flashes five
times, once every second,
followed by a two second pause.
Beeps stop after fifth iteration
but LEDs continue until problem
is solved.
Beeps Possible cause
None Computer on.
None Computer in Suspend to
RAM mode (some models
only) or normal Suspend
mode.
2 Processor thermal
protection activated:
A fan may be blocked or not
turning.
OR
The heat sink/fan assembly
is not properly attached to
the processor.
3 Processor not installed (not
an indicator of bad
processor).
4 Power failure (power supply
is overloaded).
5 Pre-video memory error.
Interpreting POST diagnostic front panel LEDs and audible codes 103
Recommended action
None
None required. Press any key or move the mouse to
wake the computer.
1. Ensure that the computer air vents are not
blocked and the processor cooling fan is
running.
2. Open hood, press power button, and see if the
processor fan spins. If the processor fan is not
spinning, make sure the fan's cable is plugged
onto the system board header.
3. If fan is plugged in, but is not spinning, then
replace heat sink/fan assembly.
4. Contact an authorized reseller or service
provider.
1. Check to see that the processor is present.
2. Reseat the processor.
1. Open the hood and ensure the 4 or 6-wire
power supply cable is seated into the
connector on the system board.
2. Check if a device is causing the problem by
removing ALL attached devices (such as hard
drives or optical drives and expansion cards).
Power on the system. If the system enters the
POST, then power off and replace one device at
a time and repeat this procedure until failure
occurs. Replace the device that is causing the
failure. Continue adding devices one at a time
to ensure all devices are functioning properly.
3. Replace the power supply.
4. Replace the system board.
CAUTION: To avoid damage to the DIMMs or the
system board, you must unplug the computer power
cord before attempting to reseat, install, or remove
a DIMM module.
1. Reseat DIMMs.
2. Replace DIMMs one at a time to isolate the
faulty module.
3. Replace third-party memory with HP memory.