Broken or shorted flashing red LED on good lightning cables



I’m using the QualMeter X to screen lightning cables, and for the most part it works very well. However, I have numerous lightning cables I know to be good (measured current draw, verified charging capability, verified communication works), but they are resulting in a red flashing LED indicating a broken or shorted connection. Why are these good cables failing on QualMeter X? What exactly is being measured to indicate the Best/Fair/Worst LED indicators?


Hi @dburrell,

Apple uses a mechanism to prevent fake lightning cables. There is a chip inside the head of the lightning plug side, which will communicate with the iDevices. It will turn on a MOSFET switch to enable the charging if it passes the communication. Thus, in order to measure the lightning cable, the qualMeter needs to simulate the communication with the cable to fool the inside chip to turn on the MOSFET switch.

However, since it’s a simulation, it might not work if Apple changes the way(or the code) of communication. Then you would experience the problem like what you have described above. The indication you’ve got might lead to the following results:

  1. The cable could be broken.
  2. If qualMeter was not able to test it and you are sure the cable is good. Then it could be a newer version lightning cable that our qualMeter has failed to communicate with it and is unable to test it.
  3. If so, following the 2nd result, your lightning cable should be a genuine Apple certified lightning cable.
  4. As far as I can tell, a 3rd party non-Apple-certified lightning cable or older version genuine lightning cable should have no problem to be tested normally as other cables on the qualMeter.

Thank you for letting us know. This situation is something new to us. It was okay for the past 3 years. We need to look into it and to see if we can find a solution for it.

Thanks again!



Thanks for your quick response. I am seeing numerous cables that fall into this bucket… they are genuine Apple cables and they fail the QualMeter X test. Can you provide a timeframe for a potential update, and if so, what format would the update take (i.e. firmware, new tester hardware, etc)?


Hi @dburrell,

To be honest, I don’t have a time frame on the fixing for now. But I’ll let you know as soon as we have figured it out.

Thanks for your patience.