The iPhone 4 headphone jack flex cable is usually damaged by water entering the headphone jack and causing corrosion. This is a common problem simply because if you are outside on the phone and it starts raining, the headphone jack is in the perfect position to collect raindrops. What generally happens is that the corrosion bridges the sensor inside the audio jack making the iPhone 4 think there are headphones plugged in. This disables the earpiece speaker and the microphone. These can be replaced by the end user and we advise you pop over to YouTube and checkout some of the videos on there on how to replace the iPhone 4 headphone jack flex cable and see if itís something you think you can do yourself, also you may want to get the iPhone 4 tool kit to make the job of opening up the iPhone a little easier.
If you are not sure whether your iPhone 4 has a faulty headphone jack flex cable or whether you have a problem with the earpiece speaker, there is a simple way to work it out. Turn the volume up or down. The onscreen display will show the volume level and above it you will see either the word (ringer) or (headphones) in brackets. If it shows headphones when there are no headphones plugged in, then the audio headphone jack flex circuit is faulty. If you try to change the volume and there is no display, your audio headphone jack flex cable is faulty. It may be possible to fix the iPhone 4 headphone jack flex cable without replacing it or disassembling your iPhone 4. Try using a thin cotton bud (ear bud) dipped in isopropyl alcohol (99% not 70%) to clean out the audio headphone jack. Itís a good idea to turn off the iPhone 4 first.
If your volume switch or mute switch is not functioning, the iPhone 4 Headphone Jack Flex cable replacement will also fix these problems. Note that the actual mute, volume up and volume down buttons are not included with this part. This part is only the circuit that is trigger when you operate the buttons. Usually the buttons themselves never need replacing unless you have lost them while the iPhone 4 is disassembled.