Why USB ports do not work. USB ports do not work on a computer - solutions

Question: Windows 7 does not see USB devices


   Friend reset operating system  Windows 7, made a boot via a USB flash drive. The system is installed, the drivers are in place, there are no unidentified devices / devices without drivers. But at the same time, AFTER the installation of the operating system, he does not see any flash-usb drive (ordinary flash drives, USB 3G modem) - he does not see, but SEES a USB keyboard and a USB mouse. We tried to rearrange flash-usb drives to other ports, but still the situation remains the same. That is - in the working ports (where the keyboard and mouse are) - zero reaction, the device also does not see. We tried everything that was possible (.reg files that allow you to see hidden unidentified devices in the device manager, etc.) - no sense. Oh yes, the most important thing, if you connect the phone, the device does not see it, but the phone itself is charging. Thank you in advance, necessary information  I will provide.

  BIOS: Award Bios

Answer:   HKEY_LOCAL_MACHINE \\ SYSTEM \\ CurrentControlSet \\ Services \\ USBSTOR
  What is the numerical value in the STAR parameter?

Question: Windows 7 - USB Devices


   Good day to everyone / morning / evening / night

Situation. there is installed windows  7 maximum.
  But when you connect a USB flash drive or modem to it, it says that the device is not recognized until you find a line similar in name to the device in the registry and delete it.
  After that, this device is recognized, but only for a while, after which "we start all over again".
  How is it treated?

Answer: andreik99
  You can see in the Device Manager. And if it was so from the beginning, then maybe the image of the OS curve and it is better to install another? And then later that thread will pop up ...

Question: Windows XP does not recognize the USB device


   Windows XP does not recognize the USB device. At the same time, MS-DOS is loaded on the same computer from the same "flash drive" and the mouse normally works in the same USB ports. Other flash drives (those that are available and serviceable) are also not recognized in win xp.

Answer:  thank you for your help. I solved the problem by installing a PCI-USB adapter

Question: USB installation  devices


Good afternoon. There is a device yusb. When connected to a PC, it is detected by the system as an unknown USB device. But after disconnecting and turning on the USB Root Hub in the device manager, it is immediately immediately detected correctly until the next shutdown. On other PCs (this is about 10 machines) this problem is not observed at all. On a problematic PC, other USB devices work without problems, and this device also worked well previously. The chipset and USB drivers from the manufacturer's website (Intel) have already been reinstalled. What could be the problem. A barcode scanner device is defined as a HID-keyboard from the manufacturer that goes without software and drivers and never needed it.

Answer:  Good afternoon. There is a device yusb. When connected to a PC, it is detected by the system as an unknown USB device. But after disconnecting and turning on the USB Root Hub in the device manager, it is immediately immediately detected correctly until the next shutdown. On other PCs (this is about 10 machines) this problem is not observed at all. On a problematic PC, other USB devices work without problems, and this device also worked well previously. The chipset and USB drivers from the manufacturer's website (Intel) have already been reinstalled. What could be the problem. A barcode scanner device is defined as a HID-keyboard from the manufacturer that goes without software and drivers and never needed it.

Question: How in Windows 7 to restrict the user the right to certain actions?


   Good day.

You can tell how to limit the user according to the list:

Now we have:
  a local network where everyone and everything walks.
  the user does what he wants (within, but this is not possible)

It is necessary:
  ban usb - done, some of the machines in racks sealed, the rest of usb filled with hot glue.
  ban cd-rom - done in user policies.
  creation ban network folders, except for those created by the administrator - not done
  ban on task manager, by all means (ctrl + alt + delete works, but shift + ctrl + esc does not work) - not done
  the prohibition of the start button, except to complete the task, restart, exit the user - is done by cutting out all the directories from default, allusers and others ...
  a ban on displaying all media (C, D, A, B and others) in the explorer - not done
  the ban on launching "left" programs - partially done, there is a list of programs, but the rest is launched through the explorer.

Answer:  Hello.

Try to read more on the registry, it helps well in lokalka administration, though you will have to apply the settings on each machine (not necessarily manually, just write the reg file once)
  reg-files are written easily and simply, but the topic is not about that ...
  I hope the following conversions in the registry will be of interest to you (which I remember by heart):

1. Save the registry file before making changes to at least another logical drive  from the installed OS.

2. To prevent the user from starting the Windows Task Manager, set the value of the DWORD DisableTaskMgr type parameter in the section
  HKEY_CURRENT_USER \\ Software \\ Microsoft \\ Windows \\ CurrentVersion \\ Policies \\ System
  equal to 1
  For even through it you can "screw up".

3. We turn to blocking usb ports:
   Branch HKEY_LOCAL_MACHINE \\ SYSTEM \\ CurrentControlSet \\ Services \\ USBSTOR
   We find the Start key in this thread, right-click and select Change
   It remains to change the values: Value 3 - Enable usb ports; 4 - turn off usb ports. We need to disable the ports, so we set the value to 4.
   A very important step, because you must close and restart the computer. Until you do this, the usb ports will function normally. After rebooting, when you connect usb-devices you will hear a characteristic sound, however, the system will not detect the mounted device.

There is another option - it suited me better in due time - sometimes it is required not to close all ports, but to make sure that only certain "flash drives" are detected on the computer ... then it’s even easier:
   Branch HKEY_LOCAL_MACHINE \\ SYSTEM \\ CurrentControlSet \\ Enum \\ USBSTOR
   B branch HKEY_LOCAL_MACHINE \\ SYSTEM \\ CurrentControlSet \\ Enum \\ USB
   Select all the folders in these branches (previously connected devices) and delete.
   Next, insert the "flash drives" that we want the PC to detect (you need to insert the device into each port, or into the port that you have not time to stick yet, since it is important for the device which port it will be detected in)
   After these steps, click RMB on the above two branches USB and USBSTOR (one at a time), select "Permissions ..." in the context menu and delete all but the system from user groups, leaving it full access.
   We restart the registry ... these branches will not be readable, as if empty. After these actions, other people's flash drives will not be detected in any port (it is easier to write a reg-file).

4. From the Start menu, you can generally close everything in the registry. I advise you to read just the registry details. You will find a lot of things. With cd-rom you figured it out, so I'll skip it.

5. Enabling this option prevents users from changing the remote administration settings of the computer.

  Parameter: NoAdminPage
  Type: REG_DWORD

By the way, on the question of how to find out who created which folders or deleted files from which machine, for me nothing, but more intelligent people say that you need a network sniffer, the ability to read logs and knowledge of network administration along with several programming languages \u200b\u200b...

6. This parameter controls the visibility of the "Devices" tab in the system properties.
  Key:
  Parameter: NoDevMgrPage
  Type: REG_DWORD
  Value: (0 \u003d Disabled, 1 \u003d Enabled)

7. This option will allow you to prevent users from turning off the computer using the "Turn off computer" command.

  Parameter: NoClose
  Type: REG_DWORD
  Value: (0 \u003d Allow shutdown, 1 \u003d Block shutdown)

8. This parameter controls the display of disks in the "explorer", it makes it possible to hide all disks or only selected ones.
  The "NoDrives" parameter determines which drives are visible. The order is set from the lowest bit - disk A: to the 26th bit - disk Z: To hide the disk, turn on its bit.
  If you do not know how to work with hexadecimal numbers, set these decimal numbers to hide the drive (s):
  A: 1, B: 2, C: 4, D: 8, E: 16, F: 32, G: 64, H: 128, I: 256, J: 512, K: 1024, L: 2048, M: 4096, N: 8192, O: 16384, P: 32768, Q: 65536, R: 131072, S: 262144, T: 524288, U: 1048576, V: 2097152, W: 4194304, X: 8388608, Y: 16777216, Z: 33554432, ALL: 67108863
  Please note: These disks will still be displayed in the File Manager; to remove the File Manager, delete the winfile.exe file.
  Key:
  Parameter: NoDrives
  Type: REG_DWORD

9. You will also find these two options useful:
  When this option is enabled, the Find command will be removed from the Start menu.
  Key:
  Parameter: NoFind
  Type: REG_DWORD
  Value: (0 \u003d Disabled, 1 \u003d Enabled)

When you enable this option, the icon will be "Network Places" will be hidden.
  In addition, this option disables the UNC property inside the Explorer interface, including the Run ... command from the Start menu. UNC paths are configured by the administrator in the Ruleset for public folders, desktop icons, the Start command, etc. It does not affect functionality command linewhen executing the "Net.exe" command.
  Key:
  Parameter: NoNetHood
  Type: REG_DWORD
  Value: (0 \u003d Disabled, 1 \u003d Enabled)

It seems so far all that I remembered, I’ll remind you again - do all the changes backups the registry. Read the rules for writing reg-files ... and ... The key (Branch) is let in the registry where to go; The parameter is the name on the right (if there is no parameter, then you can create it in the right frame by selecting the specified parameter type, and then set the value and voila. But I would still recommend using ready-made reg-files - 5 lines in notepad
  I hope it helped at least something.

Question: The laptop stopped seeing a usb modem with an extension cord


   Good afternoon. After reinstalling windows acer laptop  Aspire 5920g stopped seeing usb modem when connected with an extension cord. Before that, I connected it with an extension cord for more than a year and everything was fine. When connected, the laptop does not react at all. He sees other devices. I tried to connect a USB flash drive. Also, if you connect without a wire, it determines without problems.
  I’ll say right away. With the extension cord and the modem, everything is fine, since everything works on the second computer. I was advised to clean my contacts usb portbut I immediately threw away this option. I don’t think for half an hour while I was walking windows installation  sharply oxidized all 4 usb ports on my laptop.
  Forgot to mention. I connected a second usb modem, which also previously worked with an extension cord. It also determines only without an extension cord.
  Downloaded from. Acer website driver for the chipset - did not help. Some kind of mysticism. I no longer know what you can try to do and what could be the reason.

Answer:

Message from Steroid

firewood downloaded only to the chipset? or USB too?

There are none at the office. website

Question: When the USB device is turned on, it either doesn’t show any signs of life at all or "doesn’t accept commands"


   When you turn on the PC and booting windows, devices connected via USB either do not show any signs of life at all, or "do not accept commands."

The download scripts are as follows:
  1. Devices do not show any signs of life at all (num-lock on the keyboard is off, the mouse’s backlight is off). The mouse cursor is not visible at all.
  2. The keyboard / mouse has a backlight, but they do not receive any signals (the keyboard does not respond to keystrokes, if you press num-lock, it does not go out). The mouse cursor is also not visible.
  3. Everything works correctly (rarely)

Usually, in order to achieve normal operation, I have to reboot several times, or even completely turn off the power. At the same time, for example, in the BIOS settings, both the keyboard and mouse work correctly (because I suspect that the problem is in Windows).

It started from the time I bought an SSD (Intel 535 240gb) and installed the system on it (I downloaded the image from the MSDN torrent)

Is there anything you can do to make everything work fine without reinstalling Windows?

Answer:

Message from maxswitcher

Unfortunately, I can’t test normally. I deleted Hamachi and so far have not been able to "seize the moment" when this does not work (rebooted 20 times). Maybe the problem was in Hamachi. The next couple of days I will test and unsubscribe if a problem arises (and, in fact, try to start installing Windows).

Nevertheless, there is a bug.

Message from Rockinheart

If you disable ssd, do usb devices work correctly? (Can I check from live CD or windows installation disk / flash drive)

Even without disconnecting the SSD, in the installer (though from Windows 7) both the mouse and keyboard work correctly (3 out of 3 attempts are all fine), while Windows 10 itself worked fine from 15 times. It seems that the problem is still in Windows.

Question: Windows 7 after installing it on a new PC does not connect to the Internet and does not see a USB flash drive


   I decided to unsubscribe in my topic already, I don’t know where exactly who can help write, the components arrived in short, collected everything as it should, double-checked it 10 times, but I can’t install Windows 7, or if it is installed it does not connect to the Internet and does not see usb flash drives, although the keyboard and mouse in usb connectors are turned on and working, I looked at the drivers in windows for the presence of enthernet and PCE any kind of duck writes that it was not detected and not installed, but I didn’t think of a dvd drive without it, in short a major blockage, In what problem maybe? I put a curve Windows? I tried to write another operating system to the USB flash drive when loading through the BIOS, the file is downloaded, you select the language and where the window should appear with C, D disks, etc. a window pops up with a cancellation, a review of the buttons and it says that the driver is not worn out ... for 2 os, I have not tried them, I saw only one but half of the drivers are not installed on it (I don’t see the Internet or the flash drive) Help or discard the working image if you know where ...

Answer:  Show device manager screen

Question: USB mice periodically fall off, other USB devices work fine


   Good afternoon.
  The problem began about three weeks ago.
  There are two A4 Tech X750bf mice and a spare G-cube.
  Worked with the mouse via usb2
  At first, the x750 began to fall off. Those. works fine then disconnects reconnects and so jumps.
  I thought the problem was in the wire at the bend. Cut and soldered. The problem has not disappeared.
G-cube inserted everything was fine, then the same song. Soldered it too. Problem still exists. Demolished the driver tried to put the native one from the site. Not defined just do it. It was written that something like the computer could not get data about the usb device or something like that (device descriptor request failed). x750 At the same time, it just stopped showing signs of life besides blinking a light, as the device just doesn’t detect what something is in usb. Demolished the G-cube driver. It does not detect the device, but the x750 blinks the same diode. I tried usb3 G-cube worked fine. x750 in usb3 behaves the same as in usb2. An hour or 2 G-cube worked in usb3 normally, and again now the descriptor fails.
  Now I connected the digitizer Geniusovsky. It works normally, with it there is a sensor mouse which can only be operated on the digitizer plane.
  At least something, I can at least write here.
  Help where to look what to correct?

Z.Y. Other USB devices such as a flash drive and camera work fine in all ports.
  Windows 10 ultimate 64 operating system.
  Motherboard GA-H67A-UD3H-B3

Added after 6 minutes
  Z.Y.Y. Maybe something connected !? When the problems with the mice started, I had a second monitor connected. He fell off. Well, I just pulled the shoelaces, poked and pressed the power, scored and turned it off. But from the moment the monitor fell off and the mice began to junk!

Added after 3 hours 42 minutes
  Yes, in the last 2-3 days I reread everything.
  I start to write on the forums when nothing helps.
  Here is something that helped.
  X750bf pressed the dpi button and inserted it into usb, and lo and behold, the mouse came to life!
  There is no such magic button on the G-cube. But there is a double click button. Hold-insert-nothing!
  I took it now to work so that I could check it on another computer.
  I just inserted the same error 43 into USB.
  He took it out, inserted it into USB with a double click held down - it was determined and earned ... it worked fine for 5-10 minutes.
  Then it stopped beginning to fall off inserted every 5 seconds.
  He took it out, nothing. Then it turned out that the mouse (THIRD) still fell off again, again the A4Tech XL-750BK and the Microsoft CCK-3000 keyboard. (At home the same but CCK-2000).
  I had to, and only restarting the computer helped.
  And I included pancake rendering in 3d max

There is even a feeling that the virus hit my mice - before if there were such viruses.
  In general, I sin on food. perhaps in one of the mice something is burned out, it consumes currents incorrectly, and this affects other input devices. However, the digitizer works without problems.
  Okay...
Let's see how the reanimated X750bf will behave further
  It all started in principle with her. Before glitches with her, there were no glitches on the G-cube. And now it works and the G-cube works buggy on another computer. Kapets ...
  If there are any thoughts besides throwing the mouse out the window, I will be glad!
  And I won’t throw it away because I like to make harmful devices work! There is already a matter of principle.

Many of our readers asked for an explanation. why USB ports do not work  and also why the error pops up " Error. USB device not recognized". Finally, I found the time to write this long-awaited article. USB ports do not always cause a malfunctioning connected device.

Very often, the external device itself crashes, which is why an error about a faulty USB port pops up. Before proceeding to the next steps, make sure that the USB device you want to connect is operational (check with a friend or on another computer). If you are sure that your device is working, then this article is for you.

Reasons for the problem

They may be completely different, but you need to find out the exact reason due to which uSB ports do not work.



  • If the above methods didn’t help and still uSB ports do not work, try to go to the "Device Manager" and check the "Controllers" section for devices with a yellow exclamation mark. If present, double-click on the device and read the reason for the error.


  • Perhaps the USB ports do not work due to improperly installed drivers or their complete absence. The article will help you cope with this.
  • It is possible that USB ports do not work  because of the usual ones, but having installed and scanned a computer, we can find and

After installing the operating system on your computer windows systems  10 or transition to it with previous versions  it may happen that peripheral devicesconnected via USB ports often turn off or stop working correctly at all, while displaying warning icons in the device manager in the form of a yellow triangle, as well as in the description.
  What to do in this case? First you need to identify the culprit.
  Of course, if several devices fall off at once, then it is clear that they are most likely not to blame and the reason lies in the computer itself. If only one device is buggy, then for the diagnosis you need to carry out the following manipulations:


- Try switching to a neighboring USB port. This advice is especially relevant if the system unit is located somewhere under a table in a dusty corner and is wiped only once a year. And then, before that, you need to see if it is clogged with dust or garbage.

- Replace the connection cable. This is generally a painful place - the cords are lying around anywhere, their connectors are bent, they are crushed by an armchair or shoes, pets are nibbling, etc. As an example, you can take iPhone smartphones, in which branded cables break near the plug after a couple of months of active use.

- If it fails external hard  drive, the error most likely appears because the second connector on the cable is not connected and it lacks power.

- If there is another computer or laptop, then connect the device to it and observe the work. As an option - you can go to friends or relatives. If there the gadget functions without problems, everything will immediately become clear.

So, we came to the conclusion that the causes of the problem with USB ports are hidden in the computer. Let's look for them!

Outdated drivers and BIOS

Very often, outdated or incorrect drivers are to blame for a bus failure. This is especially noticeable when updating the system, when everything worked fine on the old OS, and after the upgrade on Windows 10, glitches started with error 43 and the message "The device is not recognized."
  To fix, go to the manufacturer’s website motherboardsearch new version software  and install it.
  An alternative is to download the Drivers Solution Pack client online and start updating drivers with it.


Usually after this, the malfunctions are eliminated completely and irrevocably.

I also want to talk about a couple of cases where problems with USB ports on Windows 10 appeared due to an outdated version of the BIOS. And both times it was not on old decrepit pieces of iron, but new aSUS laptops  after updating the predefined G8 to Tens. Everything was solved by downloading latest version  BIOS from the official site and flashing the motherboard using special utilitythat came with the kit.

Reinstalling Port Hub

Sometimes the following trick helps to correct errors with the USB: We click on the “This computer” icon with the right mouse button and select the “Management” item. You will see the “Computer Management” system snap-in. In it, select the "Device Manager" section:


Here we find the section "USB Controllers" and open it. We need the item “USB root hub”. We click on it with the right mouse button and select the "Disable" item. Close the window and restart the computer. Again we return to the dispatcher and turn on the hub. After that, all USB ports should work without problems.

Power Settings

This case is especially relevant for owners of laptops, netbooks and ultrabooks. The fact is that in order to save battery energy, the function of selective disconnection of devices is activated and if at a certain point in time a lot of consuming gadgets are connected to the computer (charging the phone, card reader, portable speaker, etc.), then Windows 10 may selectively disable one or more devices at once.

To disable this option, again go to the Device Manager and open the properties of the root USB hub. On the “Power Management” tab, uncheck the “Allow this device to be turned off to save power” checkbox. After that, close the dispatcher and reboot.

Peripheral devices such as a mouse, keyboard, webcam, printer are usually connected to a computer via USB ports. However, it often happens that one or more ports stop working. That is, when connected to a computer, for example, a flash drive, it is not recognized, the keyboard or mouse may freeze, and the printer may not respond and not print pages.

There are several likely reasons why some or all of the USB ports on your computer do not work. Let's try to understand this issue and find out what should be done to restore the normal functioning of the computer.

Checking BIOS Settings

The first thing you should pay attention to is the settings. Computer BIOS. To enter the BIOS, you need a working keyboard. If the keyboard is connected to the computer via USB and it does not work, then you need to connect a keyboard with a PS / 2 connector. Otherwise, you simply can’t do anything.

So, we go into the BIOS, for which, when you start the computer, you must press the enter key, usually this is DEL. There may be another key that appears on the screen and is indicated in the manual for the motherboard. After entering the BIOS, find the section responsible for integrated devices (Integrated Peripherals) or the section "Advanced" (Advanced). Here you should find the “Onboard Devices Configuration” subsection. It contains the parameters responsible for the operation of USB controllers: USB Function or USB 2.0 Controller. These parameters must be enabled (Enabled). And if one of them is disabled (Disabled), then point to it and press Enter, thereby enabling it. So that your changes are not discarded, you must save them by pressing F10, and confirm the save by pressing Y or Enter.

After restarting the computer, we check whether the USB ports are working. And if not, then you should look for a reason elsewhere.

USB ports on the front of the computer do not work

As a special case, your USB may not work only on the front panel. In this situation, you need to check whether the necessary connectors are connected on the motherboard and whether the wires are damaged. To do this, open the side cover of the system unit and pay attention to the connector at the bottom of the motherboard. On the board itself there is an inscription USB1 or USB2, as well as on the block itself. The wires from the block go to the front panel, and if they are disconnected or broken in one place, then you have found the cause of the malfunction. Damaged wires should be connected or replaced. It will not be superfluous to check the contact in the connector on the motherboard. It is also worth paying attention to the board located on the front panel. Perhaps there is a short circuit, by the way, such a short circuit can be triggered by accumulated dust. Therefore, be sure to clean the system unit from dust.

Problems with the device or cable

The next source of USB problems may be the cable with which you connected, for example, a printer. This malfunction is easy to identify and repair. We connect a USB flash drive to the tested connector. If it works, then we try to connect with the help of a suspicious cable other obviously working equipment, for example a USB hub. If he also refuses to work, then the reason is clearly in the cable and should be replaced.

Power outages

There are situations when the power for all devices is simply not enough. For example, when connected external hard a drive that uses two USB sockets at once, the printer or keyboard may turn off. In this case, the power supply capacity is not enough to provide energy to all consumers. In this case, the problem may not occur immediately, but some time after turning on the computer. There are several ways out of the situation. If you have a low-power power supply installed, for example, 300 watts, then it would be logical to change it to a more powerful one, 450-600 watts. You can also use an active USB hub (with external power). It will allow not only to increase the number of connected USB-devices, but also to power them from a separate power supply.

Another reason that affects the operation of USB is shrunken cMOS battery. But at the same time, every time you turn on the computer, you will observe a lost system time and date. After replacing the battery, the problem goes away. But this is not common, so you should check the remaining possible sources of malfunction.

Missing or incorrect installation of USB drivers

Causes of software failures in Windows 7/10 can be identified using Device Manager. If you notice that one or more devices does not work specifically, regardless of the port used, then this may indicate that the problem is in the device itself. Open the Control Panel and go to the Device Manager section. All connected devices will be displayed there. If the list contains items next to which is yellow exclamation mark  or instead of the name is Unknown device, then the problem is in this very device. There may be several problems.


Often, USB inputs stop working after reinstalling Windows 7/10. The reason is incorrect driver installation or the necessary drivers may not be found at all. Will have to carry out the selection and installation manually.

Often, troubleshooting simply requires updating the driver. So, if automatic windows update, and the system itself was installed for a long time, then the relevance of the software is lost, it may appear system errors. The device at the same time starts to work incorrectly, or even completely stops functioning. To update (reinstall) the drivers of the USB controller, you can use the CD / DVD-ROM with the drivers for the motherboard or download the necessary drivers from the manufacturer's website.

Also, using Device Manager, you can turn off the power-saving feature for all ports. Expand the list of used USB devices hidden in the sections “USB controllers”, “Mouse and other pointing devices”, “Keyboards”. Double-click on the desired device to open the properties window. Now switch to the “Power Management” tab and uncheck the “Allow this device to be turned off to save power” checkbox. Thus, the device will be involved always and under any circumstances.

If some equipment is not recognized, then there may be a problem with drivers already known to us, or a hardware problem consisting in a lack of contact, cable damage or controller malfunction. And often there is a situation when, when you connect a faulty device, the others stop working normally. The keyboard starts to freeze, just like the mouse, and the printer stops typing. The problem is similar to a lack of power, that is, the consumption of all the power goes to a faulty device, in which there may be an ordinary short circuit or other malfunction.

USB ports do not work due to controller damage

If none of the above actions helped restore the usability of the USB ports, then you should check the USB controller of the motherboard, which could fail. High-quality repair and diagnostics in this case should be entrusted to specialists of the service center. As an option to solve the problem, try installing an expansion card, the so-called USB PC controller, which is installed in the PCI slot on the motherboard. Such a solution is noticeably cheaper than repairing the USB controller of the motherboard, and when using an additional USB hub, the problem with the lack of ports will not be relevant at all.

As you can see, finding and fixing problems with USB ports is a rather troublesome business, and all because there can be a lot of reasons. Sequentially searching and eliminating deliberately wrong paths will allow you to identify and eliminate the malfunction.