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Question: Diagnosing MacBook Pro Hard Drive Cable Failure

I've been fixing Macs professionally (not through Apple) for well over a decade now. By far the most common thing I do is replace failing hard drives. While Apple's own tools (hardware test, Disk Utility) do almost nothing to positively confirm a failing hard drive, there are several other tools (SoftRaid, SMART Utility) that can read the SMART data and tell you for sure that a drive is failing. So unlike the Genius bar, I can quickly diagnose a bad hard drive without having to infer the problem through symptoms.


But one problem that I've noticed really being on the rise lately, is a failing hard drive cable in MacBook Pros. That's the little flat ribbon cable that connects the hard drive to the logic board. It also connects the sleep light. This is a much harder problem to diagnose, because it generally acts just like a system with a failing hard drive, but the drive will pass a real SMART test with flying colors. You might think "come on, how often does a simple cable really go bad?" Well, I've never had a traditional desktop style SATA cable go bad. But I've replaced a lot of these drive cables and I'm doing another one tomorrow. I never really know if it's going to fix the problem or not though...


... because, there's no way to directly confirm the cable is the problem. I know all about Apple service procedure. I know the official way to diagnose a problem is to start replacing parts until the computer is fixed, and that last part was your problem. But that's not how things go in the out-of-warranty world of independent Mac repair.


So I got to thinking. Computers with bad cables don't crash, or freeze. They just hang for a while randomly, then come back. JUST like a hard drive with lots of bad blocks. So what could be causing this? The only thing I can think of is SATA bus errors that only happen intermittently (on a scale relative to the amount of i/o calls a hard drive does). If that is the case, then there must be SOME kind of utility somewhere that can see these errors? There are plenty of utilities out that that have fancy 3D interfaces, but do absolutely nothing (tech tool etc). But there are a few tools that the Pros use that actually DO stuff. DiskWarrior and SMART Utility are the main tools. If I could find something that can somehow easily and definitively sniff out these bad SATA cables, that would make my life a whole lot easier.

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Dec 21, 2016 3:02 AM in response to l008com In response to l008com

Since writing this, I just came across ANOTHER 2012 13" macbook pro, with a bard hard drive cable. The computer powered on just fine but wouldn't boot. Booted off any external source no problem. Put it's hard drive in a case, it worked just fine. But booted off an external volume, the machine couldn't see it's hard drive at all. Replaced the drive cable, and it's operating normally. This is an absolute epidemic of failed hard drive cables. If only there were an easy way to diagnose this on the go.

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Oct 3, 2017 6:38 PM in response to l008com In response to l008com

I bought my MacBook Pro mid 2012 version back in August 2013 and I am just replaced the HDD cable for the third time.


I had kept the three old cables so I decided to find out what had gone wrong with them. There are 5 thin copper tacks, which connect to the 7 pin side of the SATA connector. I used a multimeter to do a continuity test on these tracks. I found that on all three cables one of these tracks had broken at the same place. The cable does a tight right angle bend at the point it passes over the optic drive. The cable flexes at this point and eventually one of the copper tracks breaks. I found that if I flexed the cable at this point the track would make and break contact.


On later versions of the MacBook Pro Apple modified the HDD mount so it would prevent the case from pressing on the HDD cable. They also introduced an upgraded cable 821-2049-A, which replaced the original 821-1480-A. Unfortunately, upgraded cable still eventually breaks. This time I have taped the cable to the optic drive to try and prevent it flexing. Time will tell if this helps. The cables are quite easy to replace and I keep a few in stock.


One way of partially checking the problem is to externally connect the HDD (e.g. use a dock or SATA to USB cable) and see if the MacBook boots correctly. You need to hold the alt key down when starting the MacBook to be able to select the external drive.

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Dec 21, 2016 3:02 AM in response to l008com In response to l008com

Since writing this, I just came across ANOTHER 2012 13" macbook pro, with a bard hard drive cable. The computer powered on just fine but wouldn't boot. Booted off any external source no problem. Put it's hard drive in a case, it worked just fine. But booted off an external volume, the machine couldn't see it's hard drive at all. Replaced the drive cable, and it's operating normally. This is an absolute epidemic of failed hard drive cables. If only there were an easy way to diagnose this on the go.

Dec 21, 2016 3:02 AM

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Jul 23, 2018 2:48 PM in response to l008com In response to l008com

Hi I am facing this problem too. I have a '11 macbook pro 13" and replaced HDD at first (having two of them I did it effortless and moneyless), then without any fix decided to buy another HDD cable and problem seemed to be fixed. I faced the same issue again, still after the same amount of time (avg 3 weeks) so the flat cable failed again. I am currently at the second cable bought and decided to not go for any buy again by now.


At the first fail the cable appeared intact, last time, instead, I felt a smell of hot plastic and observed a polished round area on the tracks leading to the HDD, clue that cable was gone again.


I have no clue about the reason of the failure.

Jul 23, 2018 2:48 PM

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Aug 31, 2017 8:05 AM in response to l008com In response to l008com

Hi,


I'm having the same issue in my wife's MBP, we attend to the Apple Authorized Service Provider, this has been replaced two times, they mention that a batch of HDD flex had this issue and that they will replace it until the issue goes away, but in the meantime now due some random restarts that sometimes happen,

The Hard disk starts to make some noise (this in a period of ~1 year ) is there an official apple recall or a communication from apple side regarding this issue?


Or how can we communicate this to apple and that they take the responsibility of their product, since we bought it the MBP never has been working as should, we have another MBP same year, same day of purchased and works totally different, or better to say: works! is responsive, turn on and off fast, etc.

What do you think we can do in this situation?

Thanks in advance!


Ernesto

Aug 31, 2017 8:05 AM

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Sep 10, 2017 9:51 AM in response to l008com In response to l008com

Hello, I have the same problem, my data cable, but I have a question if someone can help me, the part is 821-2049-a in my macbook pro, and I get the cable but the model in this new is 821-0814-a. Is there some difference ? Because my MBP Mid 2012 is working, but sometimes get freeze when I click something or trying to refresh some websites, or opening some programs. Thank you so much!!!

Sep 10, 2017 9:51 AM

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Sep 10, 2017 10:12 AM in response to l008com In response to l008com

Hi,

Do you ever notice any physical wear on the cable? One youtube "fix" I saw involved simply insulating the cable with a piece of tape from the MBP's case where it had actually scraped a tiny portion of the very thin insulation off.

Sep 10, 2017 10:12 AM

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Question marked as Helpful

Oct 3, 2017 6:38 PM in response to l008com In response to l008com

I bought my MacBook Pro mid 2012 version back in August 2013 and I am just replaced the HDD cable for the third time.


I had kept the three old cables so I decided to find out what had gone wrong with them. There are 5 thin copper tacks, which connect to the 7 pin side of the SATA connector. I used a multimeter to do a continuity test on these tracks. I found that on all three cables one of these tracks had broken at the same place. The cable does a tight right angle bend at the point it passes over the optic drive. The cable flexes at this point and eventually one of the copper tracks breaks. I found that if I flexed the cable at this point the track would make and break contact.


On later versions of the MacBook Pro Apple modified the HDD mount so it would prevent the case from pressing on the HDD cable. They also introduced an upgraded cable 821-2049-A, which replaced the original 821-1480-A. Unfortunately, upgraded cable still eventually breaks. This time I have taped the cable to the optic drive to try and prevent it flexing. Time will tell if this helps. The cables are quite easy to replace and I keep a few in stock.


One way of partially checking the problem is to externally connect the HDD (e.g. use a dock or SATA to USB cable) and see if the MacBook boots correctly. You need to hold the alt key down when starting the MacBook to be able to select the external drive.

Oct 3, 2017 6:38 PM

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Oct 3, 2017 6:58 PM in response to l008com In response to l008com

l008com wrote:


So I got to thinking. Computers with bad cables don't crash, or freeze. They just hang for a while randomly, then come back. JUST like a hard drive with lots of bad blocks. So what could be causing this?



Internal cables are actually not cables but flexible circuit boards, usually mylar, with printed circuit traces taking the place of wires. This type of cable can experience cracks in traces due to aging, heat, vibration, impact and abrasion. They can be damaged quite easily if the unit is mishandled during assembly or re-assembly.



In the case of an intermittent generic failure, the electrical continuity of a cracked trace on both sides of the crack is very often a function of the temperature of the unit at the point where the crack exists. As a unit heats up, it expands, and as it expands, the crack widens, eventually forcing a complete electrical separation to exist on both sides of the crack, hence a failure. As it cools down, electrical contact may once again be restored.


Addendum—I see now this thread is almost a year old. If the HDD/SSD is removable it has always been the go to way to diagnose by putting it in an external enclosure bypassing the internal SATA cable. Nothing new here.


One of many reasons Apple went to the PCI-e and soldered storage.

Oct 3, 2017 6:58 PM

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Oct 3, 2017 10:30 PM in response to leroydouglas In response to leroydouglas

@leroydouglas Thanks you for the interesting comment on the thermal effects on the HDD cables.


I came across this old thread when I was looking to see if anyone had found a way of improving the life of the these cable. Given that the thread comes up high in a Google search and that it has had some quite recent traffic I thought it may be help to someone if I added my experience to it.


I agree that the use of an enclose to test the HDD is old news and the only reason for mentioning it was 1008com that had recently added a comment to the thread suggesting there was no definitive way to diagnose a problem with HDD cables. My view is that if the HDD works in the enclosure but not in the MacBook it makes trying a new cable worthwhile.

Oct 3, 2017 10:30 PM

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Nov 3, 2017 10:44 PM in response to IanD1953 In response to IanD1953

Thank you for your explanation of the 821-2049-A and 821-1480-A cable differences. I couldn't find that anywhere.


I just inherited a mid-2012 13" A1278 which previous owner said she hardly used in recent years because it got so slow. After resetting the system, wiping the drive and upping the memory from the original base 4gb to 12gb, I noticed a definite improvement. But still really slow and sort of hanging up when installing new OS and other large apps. Even now on MS Office 2016 and Final Draft I get a lot of beachballing. I'm thinking I should try swapping out the Hard Drive Cable and maybe put in a spare SSD I've got lying around while I'm there.


So the cable iFixit sells says it can replace both. But it's pretty costly at $44 (with bracket). I can find some others (with bracket) on Amazon for half of that. But those specifically say they are EITHER for the 821-1480-A cables OR the 821-2049-A cable. Not both. Should I just go with the newer version 821-2049-A?


You also mentioned that Apple modified the HDD mount so it would prevent the case from pressing on the HDD cable. Even tho you said it didn't eradicate the issue, is that something that I can easily accomplish by replacing both brackets?


Any advice would be greatly appreciated.


Thanks.

Nov 3, 2017 10:44 PM

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Nov 12, 2017 5:50 AM in response to l008com In response to l008com

Woah! even I am having the same issue. I replaced the cable once, but again the replaced cable too failed. I took it to the Apple store genius bar, and they told me that either the cable has failed, or the logic board. But I can boot by connecting my HDD externally via USB drive. So guess it's the cable again. I have ordered a new cable and will hopefully fix the issue!

I was worried about the failing HDD or the logic board. But the symptoms you have mentioned exactly match mine.

Nov 12, 2017 5:50 AM

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Nov 30, 2017 7:01 PM in response to l008com In response to l008com

I am helping a friend. She has cancer and doing work for free. She has a 2010 Macbook Pro and the original hard drive failed every test, including putting it a 2nd Macbook pro where I removed the DVD bay in place for a Sata hard drive bay. It failed there too. I purchased a 240GB Samsung SSD, same form factor as original drive. The disk utility (she saved OSX install disk) showed the drive, Smart Status=Ok, everything else looked fine, but when I tried to format said drive I came up with error "POSIX reports the operation couldn't be completed. Cannot allocate memory" Is possible that the SATA cable is bad and it is the root of the error?

Nov 30, 2017 7:01 PM

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Dec 12, 2017 3:47 PM in response to l008com In response to l008com

Have a 2009 Apple Mac Pro with diagnosed bad hd cable. Certified Apple tech said because part is over five years old Apple won’t identify the part so he says he can’t replace it? How can the part be identified ... he said he’d replace it if he could identify and obtain the hd cable 13 in Mac Pro 2009. Any suggestions ?

Dec 12, 2017 3:47 PM

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Question: Diagnosing MacBook Pro Hard Drive Cable Failure