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What Does an ECM Wiring Relay Do?

Updated February 21, 2017

Today's complex automotive engines need information regarding temperature, fuel consumption, speed and pollution to operate properly. The instrument making these decisions, the Engine Control Module (ECM), needs power to operate the same as any other electronic device.

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The Engine Control Module in any automobile receives signals from various sensors throughout the vehicle to monitor engine performance. If a threatening situation occurs, the ECM sends a signal to operate a "Check Engine" light.

The ECM Wiring

Wiring comes to the ECM from various sensors but also sends signals to other devices. The fuel pump, along with several other critical parts, operates on signals from the ECM.

The ECM Wiring Relay

The ECM wiring relay provides battery voltage to the main input wire to the ECM, just like the power cord to a computer. The relay closes when you turn on the ignition.

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About the Author

Richard Asmus was a writer and producer of television commercials in Phoenix, Arizona, and now is retired in Peru. After founding a small telecommunications engineering corporation and visiting 37 countries, Asmus studied broadcasting at Arizona State University and earned his Master of Fine Arts at Brooklyn College in New York.

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