Chapter 5: Troubleshooting; Built-In Self-Test (Bist); System Board Built-In Self-Test (M-Bist) - Dell Inspiron 7501 Service Manual

Built-in self-test (BIST)

About this task
There are three different types of BIST to check the performance of display, power rail, and system board. These tests are important to
evaluate if an LCD or System board needs a replacement.
1. M-BIST: M-BIST is the system board built-in self-test diagnostics tool that improves the diagnostics accuracy of system board
embedded controller (EC) failures. M-BIST must be manually initiated before POST and can also run on a dead system .
2. L-BIST: L-BIST is an enhancement to the single LED error code diagnostics and is automatically initiated during POST.
3. LCD-BIST: LCD BIST is an enhanced diagnostic test that is introduced through Preboot System Assessment (PSA) on legacy systems.
Table 19. Functions
Purpose
Trigger
Indicator of fault
Repair instruction

System board built-in self-test (M-BIST)

About this task
Steps
1. Press and hold both the M key and the power button to initiate M-BIST.
2. The battery-status light illuminates in amber when there is a system board failure.
3. Replace the system board to fix the issue.
NOTE: The battery status LED does not illuminate if the system board is functioning properly. If further
troubleshooting is required, proceed with the applicable Guided Resolution for No Power/No POST, and so on.
M-Bist
Evaluates the health condition of the
system board.
Press the <M> key and power button.
Battery LED light with Solid Amber.
Indicates a problem with the system board.
Troubleshooting
L-Bist
Checks if the system board is supplying
power to the LCD by performing an LCD
Power Rail test.
Integrated into the single LED error code
diagnostics. Automatically initiated during
POST.
Battery LED error code of [2,8] blinks
Amber x2, then pause, then blinks White x8.
Indicates a problem with the system board.
Troubleshooting
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