System-Diagnostic Lights - Dell Latitude 7420 Service Manual

System-diagnostic lights

Table 21. System-diagnostic lights
Blinking pattern
Amber
1
1
1
1
2
2
2
2
2
2
2
2
3
3
3
White
1
2
5
6
1
2
3
4
5
6
7
8
1
2
3
Problem description
TPM detection failure
Unrecoverable SPI Flash
Failure
EC unable to program i-Fuse
Generic catch-all for
ungraceful EC code flow
errors
CPU failure
System board failure (included
BIOS corruption or ROM
error)
No memory/RAM detected
Memory/RAM failure
Invalid memory installed
System board/Chipset Error
LCD failure (SBIOS message)
LCD failure (EC detection of
power rail failure)
CMOS battery failure
PCI or Video card/chip failure
BIOS Recovery image not
found
Suggested resolution
Replace the system board.
Replace the system board.
Replace the system board.
Disconnect all power source
(AC, battery, coin cell) and
drain flea power by pressing
and holding down power
button for 3~5 seconds.
● Run the Dell Support
Assist/Dell Diagnostics
tool.
● If problem persists,
replace the system board.
● Flash latest BIOS version
● If problem persists,
replace the system board.
● Confirm that the memory
module is installed
properly.
● If problem persists,
replace the memory
module.
● Reset and swap memory
modules among the slots.
● If problem persists,
replace the memory
module.
● Reset and swap memory
modules among the slots.
● If problem persists,
replace the memory
module.
Replace the system board.
Replace the LCD module.
Replace the system board.
● Reset the main battery
connection.
● If problem persists,
replace the main battery.
Replace the system board.
● Flash latest BIOS version
Troubleshooting 81