[SOLVED] I'm looking for Huawei GR5 LTE KII-L23 repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Huawei GR5 LTE KII-L23. It's started acting up, and I'm looking for a detailed service manual with boardviews and schematics to properly diagnose and repair it. I need to take precise voltage measurements around the board, so having the right documentation would be very helpful.

Thanks in advance for your help.

Selected Answer

I actually found that service manual on a tech Discord server a while back. A really helpful member there shared a direct link to their blog and I've saved it. I'm happy to pass it along here. Hopefully, these boardviews and schematics help you fix your phone, just like they got me through my repair. Looks like we have the same model.

@Abdulrahman

Absolute legend! That's exactly the info I was searching for. This is going to save me so much time probing in the dark. Seriously, thanks a ton for sharing the link!

Hi there,

I also have the Huawei GR5 LTE KII-L23 and just downloaded the manual you shared. I'm pretty new to board-level phone repair, and this is a bit intimidating with all the tiny test points and the schematics. Could you point me in the right direction on how to start troubleshooting this ? Any advice on the first few things I should check would be a massive help.

Thanks so much for your time

General advices: start by checking the voltage at the battery connector on the board. With a known-good battery connected, you should see a steady voltage between 3.7V and 4.2V. After that, a great next step is to check the main power management IC (PMIC) for shorts. Using your multimeter in diode mode, check for shorts on the large input capacitors surrounding the PMIC.

Here are a few useful references for troubleshooting your device:
https://www.ifixit.com/Answers/View/628749/MacBook+has+something+seriously+wrong.+only+boots+after+SMC-PRAM+Reset
Take a look at comment #951
Also, this : https://xdaforums.com/t/ways-to-deal-with-paint-chipping-issue.3424505/.
You can also check this video starting from minute 9:

The Huawei GR5 LTE KII-L23 service manual and boardviews from the link above were exactly what I've been searching for. I couldn't find a complete, free copy anywhere else. Seriously, thank you for sharing this you're a lifesaver!

Hi everyone, I'm working on a Huawei GR5 LTE KII-L23 with a no power issue and need some guidance with my measurements.
I'm detecting 3.3V on the VREG_MAIN line (pin 1 of the PMIC), which looks good, but I'm getting 0V on the VDD_CPU line (pin 8) where the schematics indicate I should see about 0.9V.
Since this is a core voltage for the application processor, could this missing rail be why the device shows no signs of life?
What's the best procedure to diagnose this further? Should I check for shorts on the CPU rail first, or look at the PMIC's enable signals?
I've already verified the main 3.3V and 1.8V power rails are present and stable.

My Huawei GR5 LTE KII-L23 was working perfectly until yesterday when it suddenly went completely dead. Now it won't respond to the power button, doesn't vibrate, and shows no signs of life even when connected to a charger. I'm worried there might be a serious issue.

I have a decent multimeter, a basic soldering iron, and a healthy dose of patience. While I've successfully replaced iPhone batteries and charging ports, this will be my first attempt at actual diagnosis. The sheer density of BGA chips and microscopic components is honestly a bit overwhelming.

I'm particularly curious about the alcohol trick I've seen online where you apply isopropyl to the board and look for evaporation hotspots to locate shorts. Is this actually a reliable method for beginners, or are there better approaches I should try first with just a multimeter?

I learned this lesson the hard way last month with mine, it was declared "dead" by two different shops. The phone showed absolutely no signs of life - no charging indicator, no vibration, nothing. Before diving into complex board work, I decided to try one more basic test: wireless charging.

To my complete surprise, it actually heated up on the charging pad! This single discovery completely changed my diagnostic path. It turned out the issue wasn't with the main board or processor, but with the notoriously fragile USB-C port that had failed completely. A $15 replacement part and some careful soldering brought it back to life.

The moral? Always exhaust every external testing method before opening the device. Test wireless charging if available, try different charging methods, and don't assume the worst case scenario. Sometimes the most "dead" devices have the simplest solutions hiding in plain sight.

I suspect my issue might be related to that cheap, third-party fast charger I used at the airport last week... Now the device gets extremely hot during charging, the screen flickers at low brightness, and sometimes it randomly shuts down at 30% battery. Could this have damaged the power management IC or battery calibration?

If your Huawei GR5 LTE KII-L23 starts acting up, random reboots, fast battery drain, or connectivity issues, there are several diagnostic steps you can take before assuming the worst:

• Check your charging habits: Using poor-quality chargers or wireless pads can gradually damage your battery and charging circuit, leading to unpredictable behavior.
• Inspect the physical components: A slightly damaged charging port, worn battery, or even accumulated pocket lint can cause issues that seem like major hardware failures.
• Monitor temperature patterns: If your phone gets unusually hot during specific tasks (like camera use or gaming), it could point to a failing component rather than a software issue.
• Use diagnostic tools wisely: Ampere for battery health, phone diagnostic codes (*#0*# on many models), and a thermal camera can reveal problems without opening the device.
• Know when to stop: If you see liquid damage indicators tripped or smell burnt electronics, it's time to consult a professional before causing irreversible damage.

Also visit this link it may help : https://xdaforums.com/t/prevent-lockscreen-rotation-on-keyboard-opening.1067027/

Here's what I discovered on forums and technical databases:

Cheap alternatives often have poor color reproduction, lower brightness, or unreliable touch. Any misalignment can block the sensors, causing them to malfunction even if the part is new. It is often wise to apply Kapton tape around the target IC to protect nearby plastic connectors or smaller components from the high heat of the hot air station. The PCB serves as the nervous system of a smartphone, housing all the critical components and their intricate connections. Opening procedures, screw types, and component locations vary significantly. Restart the Device: A simple reboot can often resolve temporary software glitches. Prevent EMI: Stops interference between high-frequency components and other sensitive parts of the motherboard. "Accessory Not Supported" or "Charging Not Supported" Errors: This is a classic symptom, especially for ICs like the Tristar, indicating a failure to properly identify the charger or cable. Cotton Swabs/Lint-Free Cloths: Ideal for localized cleaning and wiping delicate surfaces. Use fine-point tweezers or a very thin plastic pry tool to gently remove any remaining fragments of the broken clips from the frame or component they were attached to. On a smartphone logic board, they act as a sacrificial link: if too much current flows through a particular line (due to a short circuit, component failure, or voltage spike), the fuse "blows" (opens the circuit), preventing damage to more expensive components like the main power management IC (PMIC) or the CPU. If this process fails , either because the encryption key is corrupted, the storage partition is damaged, or the hardware (like the eMMC/UFS storage chip or its controller) is faulty , the phone cannot access its own system files or user data, leading to the "decryption unsuccessful" error. A faulty or aging battery can severely impact your smartphone's performance and usability, making it a prime candidate for replacement. To effectively check smartphone battery connector pins, you'll need a few specialized tools. The discreet hum of a smartphone’s vibration motor plays a crucial role in user interaction, providing tactile feedback for notifications, calls, and haptic responses. This comprehensive guide will outline various methods and considerations for assessing stuttering, helping users understand its causes and potential solutions. Hot Air Settings: Set your hot air station to an appropriate temperature (e.g., 350-380°C for leaded solder, 380-420°C for lead-free solder) and a low-to-medium airflow. Proper Seating: Ensure the flex cable is fully and evenly seated in the motherboard connector, and any latching mechanism is securely closed. This is for very stubborn, flush shafts and requires advanced soldering skills. If it’s integrated with the display, you might need to carefully peel off adhesive tape or remove very tiny screws. Obstructions: Walls, metal objects, and even your body can interfere with the signal. If the problem disappears in Safe Mode: It's almost certainly a third-party app causing the issue. Advanced software can isolate which specific component is failing or underperforming. Excessive Battery Drain: A struggling amplifier or RF chip trying to compensate for poor signal can consume more power. Go to Settings -> System -> Reset options -> Erase all data (factory reset). The very first step is to confirm if water actually entered the device, or if the phone simply got wet externally and is still functioning. When performing any internal repair or maintenance, always use appropriate tools and follow established procedures to avoid bending pins or damaging flex cables during reassembly. This guide will explore the common reasons for a flickering flashlight, detail the diagnostic tools and techniques, and outline potential repair pathways to restore stable illumination to your smartphone. Do not cut too deep or too wide, and avoid touching the phone's frame. Component Sourcing: If replacing the BGA chip entirely instead of reballing the original, finding a new, programmed chip can be nearly impossible for proprietary smartphone components.

@Shelley, Not sure what you're trying to say but ok :)