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Why Does My ECM-I Fuse Keep Blowing?

by Gerald Elliott

The electronic control module (ECM) -- also called the powertrain control module (PCM) or electronic control unit (ECU) -- is a computer which controls the electronics in an automobile. The ECM 1 is one such computer; it has a fuse is installed to protect the computer from sudden power surges or other component damage -- the fuse will blow before any damage can reach the ECM. Many component defects can cause your ECM 1 fuse to blow.

O2 Sensor

Although complaints have been reported about the O2 sensor causing the ECM 1 fuse to blow, in reality it is not the O2 sensor causing the problem -- it is the placement of the O2 sensor. If the wires leading to the O2 sensor rub against the exhaust, it creates a ground; once the O2 sensor is grounded, the fuse to the ECM 1 blows. The O2 sensor must be installed in a different place to ensure the wires do not short-circuit.

Fuel Pump

Another cause of an ECM 1 fuse consistently blowing is a fuel pump problem. When the fuel pump begins to fail it overheats, causing it to drain more amperage (amp); if the amps exceed the amount of amps the ECM 1 fuse allows, the fuse will blow. Replacing the fuel pump should correct this problem.

Wiring

The ECM 1 operates via voltage sent from the battery. Anytime an electrical wire becomes frayed, burnt or damaged, the wiring leading to the ECM 1 will short-circuit; once a wire short-circuits, a power surge can occur; if the power surge exceeds the ECM 1 fuse's limitations it will blow the fuse. It is hard to track down a short circuit, but you will have to look at every wire leading to the ECM. It is best to have a qualified technician -- with the tools and devices to narrow down the specific wire causing the short -- work on such fuse problems,

Starter

The starter is the component that engages the engine when the ignition system is turned on. Voltage from the battery is sent to the starter, which then engages and starts the engine. If the starter is failing or has failed, voltage can get redirected to the ECM. The voltage or amps surge, causing the ECM 1's fuse to blow. When the starter fails you will hear a clicking noise or the engine will be hard to start.

About the Author

Gerald Elliott published his first article in 1980 in the "Stanford Daily" newspaper. Since 1988, Elliott has written and edited articles for the "Los Angeles Times," the "San Diego Union Tribune" and Ingenuity Design Solutions. Elliott received his Bachelor of Arts with a major in literature in 1970 from Stanford University.

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