What is AM1 Fuse Meaning?

AM1 is the ignition system 40a fuse with dedicated wires operated by the ignition switch. When switch to ACC/ACCESSORY position, the AM1 fuse connect to ACC. When switch to ON position, AM2 fuse connect to IG1, AM1 fuse connect to ACC and IG2. When switch to START, AM1 fuse disconnect ACC and IG2, AM2 fuse connect to IG1. 

The AM1 fuse starts the vehicle’s electrical system and other accessories, such as the ECU and sensors. The fuse is in the box near the engine or the battery.

Your car’s electrical system may calibrate to transfer a certain amount of power from the battery to the various components. This is where the AM1 fuse comes in handy. The random fusing of the bigger AM1 fuse to the smaller AM2 fuse may occur during the installation of a car alarm.

It happens when the installer doesn’t fully grasp the importance of the “ON” key position’s separation of the circuits driving the alarm’s various components. To safely connect and empower electrical devices, calculate the current capacity of the car’s electric system.

Never replace a fuse with one of greater strength. Do not install electronics (such as lights or radio) that are not part of the vehicle’s original design without first checking with the manufacturer. In the event of a component failure or a short in the circuit, the additional current flow may be too high for the wire to handle. The wire may overheat and catch fire.

How to recognize a blown AM1 fuse?

To check whether a fuse has blown, take it out of the device and look inside the central part. Discoloration of the casing means the casing melted, and a crack should be visible in the central portion. Look for a little square hole in the top of the fuse, just above each blade. 

Use a multimeter set to probe the apertures in the fuse to check if the fuse is intact and working. If there is almost no current, replace the fuse.

You can use this to double-check a fuse that does not connect to anything in your car’s electrical system. But don’t do this while installing the fuse in the fuse box. The multimeter will act as a bridge and damage your device if the circuit has a significant fault.

Why does the AM1 fuse blow?

If a fuse keeps blowing, it means there’s a short circuit somewhere in the system. If you try to bridge it or use a higher amp fuse, you’ll cause a significant malfunction.

The fuse will eventually explode when too much current draws from a circuit. The overuse of lighting or electrical equipment at once is usually to blame. A multiple outlet adapter inserted into a socket is the most common cause of this problem.

What to do when the AM1 fuse blows?

If a fuse keeps blowing, it shows a shortness somewhere in the circuit. Avoid the hassle by not bridging it or replacing the fuse with one that can handle more current. To locate the short, you’ll need to follow wires to their final destinations.

If the issue disappears after repositioning the harnesses, investigate the immediate area to find the grounding source. 

If the short fade, it might happen again. Your mechanic should be the one to fix the wiring. If you are not confident in your abilities in this area, do not do it. It isn’t too tricky but requires expertise and time to do it properly.

Can the AM1 fuse be partially blown?

The time-current curves for a fuse appear like two lines that are parallel to one another. One is the “minimum melt,” and the other is the “maximum clearing” time.

The fuse, in this context, is a heating element. It heats and melts to stop the flow of electricity. The point at which the fuse melts is the minimum melt.

To separate and clear the current, you must wait until the maximum clearing period.

When a fuse blows, it means it melted. It could also mean something interrupted the load or fault before it could completely explode.

Because of the melting, the fuse’s original durability may alter. It may now have a slightly greater impedance and will probably blow at a lower current level than before.


In our opinion, a blown AM1 fuse is an indicator of a bigger problem. A blown fuse can mean a dangerous short circuit. So before replacing the fuse, switch off all the electronic systems in the car. Replace the fuse with an identical fuse. Always hire a mechanic to replace the fuse. 

  • Eric Williams

    I'm the founder of Daily Car Tips. I wrote articles in the automotive industry for more than 10 years, published in USA and Europe. I love sharing my knowledge and insights with fellow enthusiasts. Join me on this journey as we explore the exciting world of cars together!

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