If you haven’t found the problem yet, it’s time for a classic engineering solution: try to isolate the vault within the system. If it's dropping below ~11v, you need to determine why. This means that you must confirm that you have sufficient voltage reaching the amplifier for it to operate properly. For example, some of the Sony amplifiers have lights for power, overcurrent and thermal protection. With your multimeter set to DC volts, the black meter probe on the ground terminal of the amp (not on the point where the ground wire connected to the vehicle) and the head unit on (so the amp will have remote voltage applied), touch the red probe alternately to the B+ (battery +) and remote terminals of the amp. It’s basically the electrical engineering version of the COVID-19 lockdown. If you have that connection, the shield ground connection is intact. If the amp only goes into protect when one particular speaker is connected to the amp, you have a defective speaker. If you have confirmed that you have sufficient voltage on the amplifier's B+ and remote terminals and have a good ground, procede to step 3. If the amplifier goes into protect with the RCAs plugged in (but all speaker wires disconnected), there could be several problems. Almost all amps (and all amps you should be buying) are engineered with protection circuits. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Some may have a different strip on it. 10 Best Car Stereos Under $200 in 2020 – Reviews & Top Picks, 10 Best 3-Way Car Speakers of 2020 – Reviews & Top Picks, 10 Best 8-Inch Car Subwoofers of 2020 – Reviews & Top Picks, What color the protect light is supposed to be, If the protect light blinks in code to tell you what the problem is. If the amp still goes into protect, you have a bad speaker wire or the wire is shorted to chassis ground. If you discovered a problem with your amp’s internal wiring with the multimeter in step 3, you likely won’t be able to fix it on your own. Next, check that your amp’s grounding cables are securely attached to the car. Same as step 5, unplug any cables connecting the amp to your radio, CD system, or MP3 player, and try turning it on once again. If your amp isn’t a code-talker, it’s still important to understand what its lights are saying at all times. The lights are always lit when the amp powers up but are normally green. Step 4: Check that you have a good ground. Amps go into protect mode for many reasons. One of the more common things we come across when troubleshooting amplifier installation problems related to remote turn on is when the amp will not turn on (often a result of not running a remote turn on wire at all or connecting it to a wire that doesn’t receive voltage when the ignition is … Many amplifiers will illuminate their protect LED during the mute delay (when you initially power up the amplifier). We don’t recommend taking your amp apart unless you’re certain you can put it back together. Some protect lights are green or blue instead of the usual red. No car is complete without a stereo capable of blowing out the eardrums of everyone in a 5-mile radius, but you might think you can’t, If you are tired of the poor quality of the preinstalled factory speakers in your car, a 3-way speaker is the best option to improve, If you are looking to upgrade your car’s sound system, but limited space is an issue, an 8-inch subwoofer may be the perfect option. Use the red probe on the multimeter to check the voltage on each of the amp’s ports. If you read something less than 1v, the transformer is likely OK. When there is a fault, the LED changes from green to amber. Make sure none of the connections have rattled loose from driving on bumpy roads, and check that they’re all free of dust, debris, and oxidation. Some amps don’t even have power lights, but this doesn’t mean they don’t have protect circuits. I changed it only to find my amp in p For those amplifiers this is normal. If you'd like to repair it yourself, read the Amplifier Repair Primer page. If your amp is working properly, pay attention the way the indicators light up when powering the amp up. If any of them read less than 11V with your car’s engine off, or 12V with it on, there’s a problem with the internal wiring — something that should be delivering power isn’t doing it. For those who don't know what a blown fuse looks like, the one on the left below is blown. One minute it's working and the next minute it's not, usually with the green power LED on the amp turning to red or orange. If that's the case, the amplifier will need to be repaired. At each connection, fuse or other point where the wire is not continuous, check the voltage. Sometimes the voltage will only drop when current is being drawn from the power source. If your amp feels like a hot stovetop, check and see if you’ve plugged it into a unit with a lower resistance (measured in ohms) than the amp’s minimum. We’ll start with the good news. . The resistance across fuses rated more than a few amps will be essentially 0 ohms. This article is designed to help car audio beginners understand and deal with one of the most frustrating things that can happen to any amp: the system shutting down and the “protection” light turning on, seemingly for no reason at all.