How to Tell If a Ford ECM Is Good?

by Cayden Conor

The electronic control module in a Ford cannot diagnose itself, so it gives you other signs to let you know that it is bad. The major sign is that it will give erroneous or non-existent codes when you scan the ECM with a code scanner. If the ECM malfunctions, the vehicle may or may not run, depending on which circuit or circuits are burned or defective.

Step 1

Plug the code scanner into the data link port under the driver's side dashboard. Turn the key to the "On" position. Press the "Read" button on the scanner.

Step 2

Write down all the codes you read. Cross-reference the codes to the code sheet that comes with the scanner. Write down the meaning of the codes. If a code does not appear on the code sheet but does appear on your list, circle it. This means the ECM is suspect. If there are several codes that appear on your list, but when you compare them to the sheet, it seems clear that not that many things could be wrong with the engine at the same time, the ECM is also suspect.

Step 3

Turn the ignition key to the "Off" position. Bring your wrench and set of sockets to the car. Remove the negative battery cable, using the appropriate wrench and set it aside, ensuring that it does not touch metal. Remove the passenger-side kick panel -- the panel by your feet on the side of the car, using the appropriate sockets. Remove the bolts holding the three wiring harness connectors onto the computer, using the appropriate socket.

Step 4

Pull the connectors straight out from the computer, taking care not to bend the pins. Unbolt the computer from its bracket, using the appropriate socket. Remove the cover on the back of the computer, using the appropriate socket. Smell the computer. If it smells like dead fish, the computer is bad. Look for burned circuits -- burned circuits will have brown burn marks on or near them. If you see burned circuits, the computer is bad.

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