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Q: When trying to start it only clicks on a large relay (?ECU?) under the dash passenger side.

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Completely crapped out all at one time. parked it and the next day it would not show indicators or beep or nothing. slowly it started to show indicators even while the car was stopped and key removed. Then this clicking sound started under the dash on the passenger side. When I run the part number it says ECU. Does this need replacement?

My car has 85000 miles.
My car has an automatic transmission.

Often times when there is a starting issue, there is a small part called a starter relay that is many times over looked that is usually a fairly simple and inexpensive fix. The starter relay is a small unit near the starter that directs power to the starter from the battery. When this fails, it may cause a clicking sound and will not allow the starter to engage the flywheel when you turn the key. I would suggest starting with this first before going into a much more expensive repair like an ECU. If you would like to have this taken care of, a qualified professional from YourMechanic can diagnose the starting problem and guide with proper repairs.

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