Latitude 7420/Latitude 7420 2-in-1 Service Manual

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System-diagnostic lights

Table 1. System-diagnostic lightsThe following table provides the system-diagnostic lights:
Blinking pattern		Problem description	Suggested resolution
Amber	White	Problem description	Suggested resolution
1	1	TPM detection failure	Replace the system board.
1	2	Unrecoverable SPI Flash Failure	Replace the system board.
1	5	EC unable to program i-Fuse	Replace the system board.
1	6	Generic catch-all for ungraceful EC code flow errors	Disconnect all power source (AC, battery, coin cell) and drain flea power by pressing and holding down the power button for 3~5 seconds.
2	1	CPU failure	Run the Dell Support Assist/Dell Diagnostics tool. If the problem persists, replace the system board.
2	2	System board failure (included BIOS corruption or ROM error)	Flash latest BIOS version. If the problem persists, replace the system board.
2	3	No memory/RAM detected	Confirm that the memory module is installed properly. If the problem persists, replace the memory module.
2	4	Memory/RAM failure	Reset and swap memory modules among the slots. If the problem persists, replace the memory module.
2	5	Invalid memory installed	Reset and swap memory modules among the slots. If the problem persists, replace the memory module.
2	6	System board/Chipset Error	Replace the system board.
2	7	LCD failure (SBIOS message)	Replace the LCD module.
2	8	LCD failure (EC detection of power rail failure)	Replace the system board.
3	1	CMOS battery failure	Reset the CMOS battery connection. If the problem persists, replace the CMOS battery.
3	2	PCI or Video card/chip failure	Replace the system board.
3	3	BIOS Recovery image not found	Flash latest BIOS version. If the problem persists, replace the system board.
3	4	BIOS Recovery image found but invalid	Flash latest BIOS version. If the problem persists, replace the system board.
3	5	Power rail failure	Replace the system board.
3	6	Flash corruption detected by SBIOS	Press the power button for over 25 seconds to do RTC reset. If the problem persists, replace the system board. Disconnect all power source (AC, battery, coin cell) and drain flea power by pressing and holding down the power button 3~5 seconds to ensure all power are drained. Run "BIOS recovery from USB", and the instructions are in the website Dell support. If the problem persists, replace the system board.
3	7	Timeout waiting on ME to reply to HECI message	Replace the system board.
4	1	Temporary Battery Failure	4,1 code is applicable for thirty seconds. If the problem does not resolve itself within this time, the battery transitions to Permanent Battery Failure and the Amber Light keeps blinking. Replace the battery.
4	3	LCD Panel Failure (potential cracked panel)	Replace the display panel.
4	4	Power Rail Failure at system board side	Replace the system board and display cable (EDP).
4	5	LCD Panel Failure and Power Rail Failure at system board side	Replace the system board, display panel, and display cable (EDP).
4	6	Display Cable (EDP) Failure	Reconnect the EDP display cable to the system board. If the 4,6 code persists, replace the display cable (EDP).

NOTE:Blinking 3-3-3 LEDs on Lock LED (Caps-Lock or Num-Lock), Power button LED (without Fingerprint reader), and Diagnostic LED indicates failure to provide input during LCD panel test on Dell SupportAssist Pre-boot System Performance Check diagnostics.