Built-In Self-Test (Bist); M-Bist; Lcd Power Rail Test (L-Bist) - Dell Latitude 5490 Owner's Manual

4. Press the arrow in the lower-right corner to go to the page listing.
The detected items are listed and tested.
5. To run a diagnostic test on a specific device, press Esc and click Yes to stop the diagnostic test.
6. Select the device from the left pane and click Run Tests.
7. If there are any issues, error codes are displayed.
Note the error code and contact Dell.
or
8. Shut down the computer.
9. Press and hold the Fn key, while pressing the power button, and then release both.
10. Repeat steps 3–7 above.

Built-in self-test (BIST)

M-BIST

M-BIST (Built In Self-Test) is the system board's built-in self-test diagnostics tool that improves the diagnostics accuracy of
system board embedded controller (EC) failures.
NOTE: M-BIST can be manually initiated before POST (Power On Self Test).
How to run M-BIST
NOTE: M-BIST must be initiated on the system from a power-off state either connected to AC power or with battery only.
1. Press and hold both the M key on the keyboard and the power button to initiate M-BIST.
2. With both the M key and the power button held down, the battery indicator LED may exhibit two states:
a. OFF: No fault detected with the system board
b. AMBER: Indicates a problem with the system board
3. If there is a failure with the system board, the battery status LED will flash one of the following error codes for 30 seconds:
Table 17. LED error codes
Blinking Pattern
Amber
2
2
1
2
4. If there is no failure with the system board, the LCD will cycle through the solid color screens described in the LCD-BIST
section for 30 seconds and then power off.

LCD Power rail test (L-BIST)

L-BIST is an enhancement to the single LED error code diagnostics and is automatically initiated during POST. L-BIST will check
the LCD power rail. If there is no power being supplied to the LCD (i.e., the L-BIST circuit fails), the battery status LED will flash
either an error code [2,8] or an error code [2,7].
NOTE: If L-BIST fails, LCD-BIST cannot function as no power will be supplied to the LCD.
White
1
8
1
4
Possible Problem
CPU Failure
LCD Power Rail Failure
TPM Detection Failure
Unrecoverable SPI Failure
Troubleshooting 89