HP Pavilion xz300, Service Manual, Page: 87 / 100

Technology Code ID) Troubleshooting and Diagnostics 3-25
Power-On Self-Test
The POST (Power-On Self-Test) is a series of initialization routines and diagnostic tests that the
system BIOS runs when the notebook boots. The system BIOS will not boot the operating system if
system memory, the CPU, DMA, or interrupt controller fails the POST diagnostic tests. POST
progress is indicated by a sequence of codes, and error messages are displayed if possible.
You should not necessarily interpret the failure of one or more POST tests as a hardware, software, or
firmware failure. If an error message appears, confirm the problem using other diagnostic tools. Not
all POST messages indicate a hardware, software, or firmware failure—some messages are for
information only.
First, confirm the failure by performing a “clean” boot, as described below: If the notebook fails to
restart with a clean boot, it requires repair.
1. Remove all accessories, including SDRAM modules, PC cards, printer, external monitor, pointing
device, and keyboard.
2. Provide “clean” AC power—no auto adapter or unusual AC adapter configuration.
3. Press the reset switch to return the notebook to a known state.
If the BIOS detects a terminal error condition, it halts POST after issuing a terminal error beep code
and/or displaying a message (see the following table). The beep code indicates the POST routine in
which the terminal error occurred.
If the system fails after you make changes using the BIOS configuration utility, reset the notebook,
enter the BIOS configuration utility, and install the defaults or correct the error.
Table 3-3. Insyde MobilePRO BIOS POST Beep Codes and Messages
Beep Code Message Description
5 short, 1 long FAULTY DMA PAGE REGISTERS DMA page registers do not function properly.
4 short, 1 long,
1 short FAULTY REFRESH CIRCUIT RAM refresh circuit does not function properly.
4 short, 2 long ROM CHECKSUM INCORRECT BIOS ROM checksum failed.
3 short; 1 long,
2 short CMOS RAM TEST FAILED CMOS RAM test failed.
3 short, 1 long,
1 short, 1 long DMA CONTROLLER FAULTY DMA controller does not work properly.
3 short; 2 long,
1 short INTERRUPT CONTROLLER FAILED Interrupt controller does not work properly.
3 short; 3 long (None) Keyboard controller failed to respond to the self-
test command.
2 short, 1 long;
3 short (None) No video device found.
2 short, 1 long;
2 short, 1 long (None) No RAM installed.
(None) KEYBOARD CONTROLLER FAILURE Keyboard controller failed during system inquiry
about connected devices.
(None) KEYBOARD FAILURE Keyboard fails to respond or no keyboard is
connected.
(None) CMOS FAILURE - RUN SCU CMOS data error, probably due to loss of battery
power.
(None) CMOS CHECKSUM INVALID - RUN SCU CMOS checksum error.