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Ask Mauricio Your Own Question
Mauricio, Technician
Category: Car
Satisfied Customers: 845
Experience:  15 years working in all makes and models
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A new question is answered every 9 seconds check engine light , but car starts

Customer Question

could i have a bad ecu , , started car engine rpm at 2900 , engine light stayed on steady, car died engine light stayed on , tried to start car , no start , turned ignition off and waited a moment , turned key on and no light at all , turned key off , then back on and engine light flashed 1 time and nothing , the same two more times , gave up for moment and removed code reader , started car it ran normal for a moment then idle dropped real low engine backfired and died , turned key off inserted code reader turned key on , gives code 12 repeatedly , you hear fans on & off ,then click-click-click ,these clicks kinda sound like something shorting out under the hood ,then check engine lights go out , car not running , no check engine light , but car starts , but then chokes out & dies
Submitted: 7 years ago.
Category: Car
Expert:  Mauricio replied 7 years ago.



Tests/Procedures:Check the power/ground to the ignition module when cranking.
Scope test the cam and crank sensor signals at the ignition module, pins k and f.
Each should have a square wave signal.
Potential Causes:Crankshaft Position (CKP) Sensor
Ignition Module

Customer: replied 7 years ago.
i have no scope , what i do have is an ohm meter , can i do anything with this
Expert:  Mauricio replied 7 years ago.
not really, you need a scope to do this diagnostic, the cam and crank sensor is more likelly to be the problem. you can tap test the sensors.
Customer: replied 7 years ago.
tap test ??????????
Expert:  Mauricio replied 7 years ago.

Tap on the sensors and see any improvent