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Hi. Yesterday while replacing the ignition coil, my mechanic mistakenly connected two wires of ignition coil while the engine was on. And then car stopped and not starting. Just cranking. He checked for the fuses but nothing worked. Electrician says its ecu problem, now my car is nissan teana and most of the people are not ready to repair it. What should I do now?
 

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Welcome to Allpar. What year and which engine? I have moved this to non-Mopar support.
These engines use coil-on-plug where each spark plug has its own coil for spark.
While it is possible to damage an ECU by shorting it out, I would want to do some more diagnosis before condemning and replacing it.
Is the ECU giving any fault codes? Is the 'check engine' light on and can an engine code reader or scan tool communicate with the ECU?
 

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Welcome to Allpar. What year and which engine? I have moved this to non-Mopar support.
These engines use coil-on-plug where each spark plug has its own coil for spark.
While it is possible to damage an ECU by shorting it out, I would want to do some more diagnosis before condemning and replacing it.
Is the ECU giving any fault codes? Is the 'check engine' light on and can an engine code reader or scan tool communicate with the ECU?
Its not giving any error msg... Electrician said that ignition line on ecu might be damaged.. yes we are able to connect to ecu via scan tool... he said might be some ic issue...
 

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We don't have that model in the U.S., but diagnosis should be similar with other Nissan products.
No error messages means that diagnostics will have to start with the basics. The car powers the (+) side of the coils and switches the (-) side on and off to fire the spark.
The crankshaft position sensor triggers the ECU to fire the coil spark at the correct time. See if the ECU is at least seeing the crank sensor pulse.
Battery and ignition switch power to the ECU and good grounds must be present.

If you disconnect a spark plug coil connector or an engine sensor and then crank the engine, it should induce an error code and light the 'ck eng' light. See if the ECU is able to do this, then erase the code.

These aren't the particular service manuals for the car, but the diagnostic steps may be similar. Nissan may use the same wire colors on all its models:
http://pdf.textfiles.com/manuals/AUTOMOBILE/NISSAN/maxima/2000/ec.pdf
or
http://pdf.textfiles.com/manuals/AUTOMOBILE/NISSAN/FX/2004.0_FX45-35/ec.pdf

Sometimes when an ECU goes into 'protection' mode from a short, it has to be reset with a battery disconnect after the short is repaired. The the ECU will resume proper operation if it senses that the short has been removed. Has this been tried?
 

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Hi. Yesterday while replacing the ignition coil, my mechanic mistakenly connected two wires of ignition coil while the engine was on. And then car stopped and not starting. Just cranking. He checked for the fuses but nothing worked. Electrician says its ecu problem, now my car is nissan teana and most of the people are not ready to repair it. What should I do now?
I don't understand the sequence of events. How can you replace an ignition coil with the engine running, and why would anyone?
Why was the coil being replaced at all?
 

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Discussion Starter #7
We don't have that model in the U.S., but diagnosis should be similar with other Nissan products.
No error messages means that diagnostics will have to start with the basics. The car powers the (+) side of the coils and switches the (-) side on and off to fire the spark.
The crankshaft position sensor triggers the ECU to fire the coil spark at the correct time. See if the ECU is at least seeing the crank sensor pulse.
Battery and ignition switch power to the ECU and good grounds must be present.

If you disconnect a spark plug coil connector or an engine sensor and then crank the engine, it should induce an error code and light the 'ck eng' light. See if the ECU is able to do this, then erase the code.

These aren't the particular service manuals for the car, but the diagnostic steps may be similar. Nissan may use the same wire colors on all its models:
http://pdf.textfiles.com/manuals/AUTOMOBILE/NISSAN/maxima/2000/ec.pdf
or
http://pdf.textfiles.com/manuals/AUTOMOBILE/NISSAN/FX/2004.0_FX45-35/ec.pdf

Sometimes when an ECU goes into 'protection' mode from a short, it has to be reset with a battery disconnect after the short is repaired. The the ECU will resume proper operation if it senses that the short has been removed. Has this been tried?
Thanks, but we tried re installing the ecu, electrician did some ic works.... but no luck.. he is going to try that again...
 

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Discussion Starter #8
I don't understand the sequence of events. How can you replace an ignition coil with the engine running, and why would anyone?
Why was the coil being replaced at all?
My mechanic was the superman, he was changing the old wire... and then he connected that incorrectly.... and when it was not working... he tried to swap the wire while the car was running...
 
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