Lenovo ThinkPad L14 Gen 1 Owner's manual

ThinkPad L14 Gen 4 and L15 Gen 4
Hardware Maintenance Manual

First Edition (April 2023)
© Copyright Lenovo 2023.
LIMITED AND RESTRICTED RIGHTS N TICE: If data or software is delivered pursuant to a General Services
Administration “GSA” contract, use, reproduction, or disclosure is subject to restrictions set forth in Contract No. GS-
35F-05925.

Contents
About this manual . . . . . . . . . . . . iii
Chapter . Safety information . . . . . .
General safety . . . . . . . . . . . . . . . . 1
Electrical safety . . . . . . . . . . . . . . . . 1
Safety inspection guide . . . . . . . . . . . . . 3
Handling devices that are sensitive to electrostatic
discharge . . . . . . . . . . . . . . . . . . 3
Grounding requirements . . . . . . . . . . . . 4
Safety notices (multilingual translations) . . . . . . 4
Chapter 2. Important service
information . . . . . . . . . . . . . . . 9
Strategy for replacing FRUs . . . . . . . . . . 19
Strategy for replacing a solid-state drive . . . 19
How to use error message . . . . . . . . . 20
Strategy for replacing FRUs for CT , special-bid,
and standard models. . . . . . . . . . . . . 20
Product definition . . . . . . . . . . . . 20
FRU identification . . . . . . . . . . . . 20
Chapter 3. General checkout . . . . . 2
What to do first . . . . . . . . . . . . . . . 21
Checkout guide . . . . . . . . . . . . . . . 22
Diagnosing problems . . . . . . . . . . . 22
Quick test programs . . . . . . . . . . . 23
UEFI diagnostic program . . . . . . . . . 23
Bootable diagnostic programs . . . . . . . 24
Power system checkout . . . . . . . . . . . 24
Checking the ac power adapter . . . . . . . 25
Checking the built-in battery and operational
charging . . . . . . . . . . . . . . . . 25
Checking the coin-cell battery . . . . . . . 25
Chapter 4. Related service
information . . . . . . . . . . . . . . . 27
Reset or restore Windows . . . . . . . . . . . 27
Passwords. . . . . . . . . . . . . . . . . 27
Power-on password . . . . . . . . . . . 27
NVMe passwords . . . . . . . . . . . . 28
Supervisor password . . . . . . . . . . . 28
System management password. . . . . . . 28
How to remove the power-on password . . . 29
How to remove the NVMe password . . . . . 29
How to remove the system management
password . . . . . . . . . . . . . . . 29
Power management . . . . . . . . . . . . . 30
Sleep mode . . . . . . . . . . . . . . 30
Hibernation mode . . . . . . . . . . . . 31
Symptom-to-FRU index . . . . . . . . . . . 31
Numeric error codes . . . . . . . . . . . 32
Error messages . . . . . . . . . . . . . 33
Beep errors. . . . . . . . . . . . . . . 33
No-beep symptoms . . . . . . . . . . . 35
LCD-related symptoms . . . . . . . . . . 36
Intermittent problems . . . . . . . . . . . 37
Undetermined problems . . . . . . . . . 37
Chapter 5. Special keys . . . . . . . . 39
Chapter 6. Locations . . . . . . . . . 4
Locating computer controls and connectors . . . 41
Front . . . . . . . . . . . . . . . . . 41
Left and right . . . . . . . . . . . . . . 43
Rear . . . . . . . . . . . . . . . . . 45
Bottom . . . . . . . . . . . . . . . . 46
Locating FRUs and CRUs . . . . . . . . . . . 47
Major FRUs and CRUs . . . . . . . . . . 48
LCD FRUs and CRUs . . . . . . . . . . . 54
Miscellaneous parts . . . . . . . . . . . 55
Connector and cable guide . . . . . . . . 56
Looking up FRU information . . . . . . . . . . 62
Chapter 7. FRU replacement
notices . . . . . . . . . . . . . . . . . 63
Service tool kit . . . . . . . . . . . . . . . 63
Screw notices . . . . . . . . . . . . . . . 63
Retaining serial numbers . . . . . . . . . . . 64
Restoring the serial number of the system
unit . . . . . . . . . . . . . . . . . . 64
Retaining the UUID. . . . . . . . . . . . 65
Reading or writing the ECA information . . . . 65
Chapter 8. Removing or replacing a
FRU. . . . . . . . . . . . . . . . . . . 67
General guidelines . . . . . . . . . . . . . . 67
Before servicing the computer . . . . . . . . . 67
Disabling the built-in battery . . . . . . . . 67
Removing the nano-SIM-card and nano-SIM-
card tray . . . . . . . . . . . . . . . . 68
Removing the microSD card (if any) . . . . . 68
1010 Keyboard . . . . . . . . . . . . . . . 69
1020 Base cover assembly . . . . . . . . . . 72
1030 2242 M.2 solid-state drive, bracket, and
thermal pads . . . . . . . . . . . . . . . . 74
1040 Wireless WAN card (for selected models) . . 76
© Copyright Lenovo 2023 i

1050 Wireless LAN card (for UMA models) . . . . 78
1060 Speaker . . . . . . . . . . . . . . . 79
1070 Memory module . . . . . . . . . . . . 80
1080 USB and microSD bracket . . . . . . . . 81
1090 USB and microSD board and cable . . . . . 82
1100 Heat sink . . . . . . . . . . . . . . . 84
1110 Thermal fan . . . . . . . . . . . . . . 86
1120 Built-in battery . . . . . . . . . . . . . 86
1130 Coin-cell battery . . . . . . . . . . . . 88
1140 Smart card reader and cable (for selected
models) . . . . . . . . . . . . . . . . . . 89
1150 NFC module and NFC cable (for selected
models) . . . . . . . . . . . . . . . . . . 90
1160 Trackpad and trackpad cable . . . . . . . 91
1170 Fingerprint reader cable (for selected
models) . . . . . . . . . . . . . . . . . . 95
1180 Power board and power button with or
without fingerprint reader . . . . . . . . . . . 97
1190 I/ bracket . . . . . . . . . . . . . . 100
1200 System board . . . . . . . . . . . . . 101
1210 LCD unit . . . . . . . . . . . . . . . 104
1220 Keyboard bezel assembly . . . . . . . . 107
2010 LCD bezel with webcam privacy shutter . . . 108
2020 LCD panel and elastic adhesive tapes . . . . 108
2030 LCD/camera/microphone cable . . . . . . 110
2040 Hinges . . . . . . . . . . . . . . . . 111
2050 Camera-and-microphone module . . . . . 111
2060 Wireless antenna assembly . . . . . . . . 113
2070 LCD cover assembly. . . . . . . . . . . 115
Appendix A. Notices . . . . . . . . . . 7
Appendix B. Abbreviation table . . . . 9
ii ThinkPad L14 Gen 4 and L15 Gen 4 Hardware Maintenance Manual

About this manual
This manual contains service and reference information for the following products:
Product name Machine type (MT)
ThinkPad L14 Gen 4 21H1, 21H2, 21H5, and 21H6
ThinkPad L15 Gen 4 21H3, 21H4, 21H7, and 21H8
ThinkPad L14 Gen 4 and ThinkPad L15 Gen 4 might be shipped with different microprocessors, namely
Intel® and Advanced Micro Devices (AMD). Hereby Intel models and AMD models are used to distinguish
computer models with different microprocessors.
ThinkPad L14 Gen 4 and ThinkPad L15 Gen 4 also might be shipped with different GPUs (graphics
processing units), namely Discrete GPU (DIS) and Unified Memory Architeture (UMA). Hereby DIS models
and UMA models are used to distinguish computer models with different GPUs.
Use this manual along with the advanced diagnostic tests to troubleshoot problems.
Important:
• This manual is intended only for trained service technicians who are familiar with products. Use this
manual along with the advanced diagnostic tests to troubleshoot problems effectively.
• Depending on the model, some hardware configuration and software programs might not be available on
the computer. Some statements in this manual might not be applicable to the computer.
• Before servicing a product, be sure to read all the information under Chapter 1 “Safety information” on
page 1 and Chapter 2 “Important service information” on page 19.
© Copyright Lenovo 2023 iii

iv ThinkPad L14 Gen 4 and L15 Gen 4 Hardware Maintenance Manual

Chapter . Safety information
This chapter presents following safety information that you need to be familiar with before you service a
notebook computer.
• “General safety” on page 1
• “Electrical safety” on page 1
• “Safety inspection guide” on page 3
• “Handling devices that are sensitive to electrostatic discharge” on page 3
• “Grounding requirements” on page 4
• “Safety notices (multilingual translations)” on page 4
General safety
Follow these rules to ensure general safety:
• bserve good housekeeping in the area of the machines during and after maintenance.
• When lifting any heavy object:
1. Ensure that you can stand safely without slipping.
2. Distribute the weight of the object equally between your feet.
3. Use a slow lifting force. Never move suddenly or twist when you attempt to lift.
4. Lift by standing or by pushing up with your leg muscles; this action removes the strain from the
muscles in your back. Do not attempt to lift any object that weighs more than 16 kg (35 lb) or that you
think is too heavy for you.
• Do not perform any action that causes hazards to the customer, or that makes the equipment unsafe.
• Before you start the machine, ensure that other service technicians and the customer's personnel are not
in a hazardous position.
• Place removed covers and other parts in a safe place, away from all personnel, while you are servicing the
machine.
• Keep your tool case away from walk areas so that other people will not trip over it.
• Do not wear loose clothing that can be trapped in the moving parts of a machine. Ensure that your sleeves
are fastened or rolled up above your elbows. If your hair is long, fasten it.
• Insert the ends of your necktie or scarf inside clothing or fasten it with a nonconductive clip, about 8
centimeters (3 inches) from the end.
• Do not wear jewelry, chains, metal-frame eyeglasses, or metal fasteners for your clothing, because metal
objects are good electrical conductors.
• Wear safety glasses when you are hammering, drilling, soldering, cutting wire, attaching springs, using
solvents, or working in any other conditions that might be hazardous to your eyes.
• After service, reinstall all safety shields, guards, labels, and ground wires. Replace any safety device that
is worn or defective.
• Reinstall all covers correctly before returning the machine to the customer.
• Fan louvers on the machine help to prevent overheating of internal components. Do not obstruct fan
louvers or cover them with labels or stickers.
Electrical safety
bserve the following rules when working on electrical equipment.
© Copyright Lenovo 2023

Important:
• Use only approved tools and test equipment. Some hand tools have handles covered with a soft material
that does not insulate you when working with live electrical currents.
• Many customers have, near their equipment, rubber floor mats that contain small conductive fibers to
decrease electrostatic discharges (ESD). Do not use this type of mat to protect yourself from electrical
shock.
• Find the room emergency power-off (EP ) switch, disconnecting switch, or electrical outlet. If an electrical
accident occurs, you can then operate the switch or unplug the power cord quickly.
• Do not work alone under hazardous conditions or near equipment that has hazardous voltages.
• Disconnect all power before:
– Performing a mechanical inspection
– Working near power supplies
– Removing or installing main units
• Before you start to work on the machine, unplug the power cord. If you cannot unplug it, ask the customer
to power off the wall box that supplies power to the machine, and to lock the wall box in the off position.
• If you need to work on a machine that has exposed electrical circuits, observe the following precautions:
– Ensure that another person, familiar with the power-off controls, is near you. That person must be there
to switch off the power, if necessary.
– Use only one hand when working with powered-on electrical equipment; keep the other hand in your
pocket or behind your back.
CAUTION:
An electrical shock can occur only when there is a complete circuit. By observing the above rule,
you may prevent a current from passing through your body.
– When using testers, set the controls correctly and use the approved probe leads and accessories for
that tester.
– Stand on suitable rubber mats (obtained locally, if necessary) to insulate you from grounds such as
metal floor strips and machine frames.
bserve the special safety precautions when you work with very high voltages. Instructions for these
precautions are in the safety sections of maintenance information. Use extreme care when measuring high
voltages.
• Regularly inspect and maintain your electrical hand tools for safe operational condition.
• Do not use worn or broken tools and testers.
• Never assume that power has been disconnected from a circuit. First, check that it has been powered off.
• Always look carefully for possible hazards in your work area. Examples of these hazards are moist floors,
nongrounded power extension cables, power surges, and missing safety grounds.
• Do not touch live electrical circuits with the reflective surface of a plastic dental mirror. The surface is
conductive; such touching can cause personal injury and machine damage.
• Do not service the following parts with the power on:
– Power supply units
– Fans
– Units similar to those listed above
This practice ensures correct grounding of the units.
• If an electrical accident occurs:
– Use caution; do not become a victim yourself.
– Switch off power.
– Send another person to get medical aid.
2ThinkPad L14 Gen 4 and L15 Gen 4 Hardware Maintenance Manual

Safety inspection guide
The purpose of this inspection guide is to assist you in identifying potentially unsafe conditions. As each
machine was designed and built, required safety items were installed to protect users and service
technicians from injury. This guide addresses only those items. You should use good judgment to identify
potential safety hazards due to attachment of non-ThinkPad / non-Lenovo features or options not covered by
this inspection guide.
If any unsafe conditions are present, you must determine how serious the apparent hazard could be and
whether you can continue without first correcting the problem.
Consider these conditions and the safety hazards they present:
• Electrical hazards, especially primary power (primary voltage on the frame can cause serious or fatal
electrical shock)
• Explosive hazards, such as a damaged CRT face or a bulging capacitor
• Mechanical hazards, such as loose or missing hardware
To determine whether there are any potentially unsafe conditions, use the following checklist at the
beginning of every service task. Begin the checks with the power off, and the power cord disconnected.
Checklist:
1. Check exterior covers for damage (loose, broken, or sharp edges).
2. Turn off the computer. Disconnect the power cord.
3. Check the power cord for:
a. A third-wire ground connector in good condition. Use a meter to measure third-wire ground
continuity for 0.1 ohm or less between the external ground pin and the frame ground.
b. The power cord should be the authorized type specified for your computer. Go to: https://
support.lenovo.com/partslookup.
c. Insulation must not be frayed or worn.
4. Check for cracked or bulging batteries.
5. Remove the cover.
6. Check for any obvious non-ThinkPad / non-Lenovo alterations. Use good judgment as to the safety of
any non-ThinkPad / non-Lenovo alterations.
7. Check inside the unit for any obvious unsafe conditions, such as metal filings, contamination, water or
other liquids, or signs of fire or smoke damage.
8. Check for worn, frayed, or pinched cables.
9. Check that the power-supply cover fasteners (screws or rivets) have not been removed or tampered
with.
Handling devices that are sensitive to electrostatic discharge
Any computer part containing transistors or integrated circuits (ICs) should be considered sensitive to
electrostatic discharge (ESD). ESD damage can occur when there is a difference in charge between objects.
Protect against ESD damage by equalizing the charge so that the machine, the part, the work mat, and the
person handling the part are all at the same charge.
Notes:
1. Use product-specific ESD procedures when they exceed the requirements noted here.
Chapter 1.Safety information 3

2. Ensure that the ESD protective devices you use have been certified (IS 9000) as fully effective.
When handling ESD-sensitive parts:
• Keep the parts in protective packages until they are inserted into the product.
• Avoid contact with other people.
• Wear a grounded wrist strap against your skin to eliminate static on your body.
• Prevent the part from touching your clothing. Most clothing is insulative and retains a charge even when
you are wearing a wrist strap.
• Use a grounded work mat to provide a static-free work surface. The mat is especially useful when
handling ESD-sensitive devices.
• Select a grounding system, such as those listed below, to provide protection that meets the specific
service requirement.
Note: The use of a grounding system to guard against ESD damage is desirable but not necessary.
– Attach the ESD ground clip to any frame ground, ground braid, or green-wire ground.
– When working on a double-insulated or battery-operated system, use an ESD common ground or
reference point. You can use coax or connector-outside shells on these systems.
– Use the round ground prong of the ac plug on ac-operated computers.
Grounding requirements
Electrical grounding of the computer is required for operator safety and correct system function. Proper
grounding of the electrical outlet can be verified by a certified electrician.
Safety notices (multilingual translations)
The safety notices in this section are provided in the following languages:
• English
• Arabic
• Brazilian Portuguese
• French
• German
• Hebrew
• Japanese
• Korean
• Spanish
• Traditional Chinese
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6ThinkPad L14 Gen 4 and L15 Gen 4 Hardware Maintenance Manual

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2 ThinkPad L14 Gen 4 and L15 Gen 4 Hardware Maintenance Manual

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4 ThinkPad L14 Gen 4 and L15 Gen 4 Hardware Maintenance Manual