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Discussion Starter · #1 ·
Hello everyone,

First post here, anyway I have a 2003 Nissan Altima Automatic 2.5 with 21000 original miles. Was running great one day, parked it and the next day went to start it and it will just crank but will not start, additionally the cooling fans go full blast as soon as i turn the the key to the "On" position. I initially thought it was either the Crank or camshaft positioning sensor(s) so to make sure, I hooked up my OBD2 code reader to retrieve any codes but it will not connect to the ECU, as soon as the key gets to the on position the fans go full blast and eventually will drain the battery. I am thinking that the ECU is not coming on, thus I am not able to connect my OBD2 code reader, I checked all fuses, including the 15A fuse in the IPDM (fuse for the ECU) and all fuses are good there, also checked grounds and they look solid. Any guidance or help will be much appreciated. By the way I have ample experience in electronics, just not in the automobile industry, checking things such as signals, waveforms etc should no be an issue, I have test equipment (Oscilloscope, multimeter, logic probes etc). Can someone tell me where the ECU is located, maybe pin-out of the connector?. I want to check if I am getting power to the ECU and start there.

Thanks,

Mario.
 

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Discussion Starter · #2 ·
No one knows where the ECM is located or ever seen symptoms like the ones I am experiencing?. On Black Friday I bought an “X Tool D8” and tried it today, I am able to connect to the “ TCM” and “BCM” but can’t connect to the “IPDM” or “ECU”, a little help would be appreciated!!.

Thx, Mario.
 

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Discussion Starter · #7 ·
Thank you both for your replies. I was able to determine that in fact it was a “bad” ECU/ECM. I ordered a used ECU (same part number), it arrived yesterday and removed the old one today and replaced it, i am now able to communicate with the ECU using the scanning tool I bought in Amazon. I also was able to program my existing keys to the replacement ECM, so I went to start it and again it would crank but would not start, but this time being able to talk to the ECU I was able to determine that I also had a bad camshaft sensor, after replacing it with a new one I had it finally started and took it for a test drive and feels fine, this problem is now solved.
I do have another question related to the ECM replacement. Since this ECU is from another car, do I have to “write” my VIN code to this ECM? Using the tool that I have (Xtool D8) I was not able to find a function to enter the VIN on the ECU, the car runs fine, but was wondering if this would be a problem when the vehicle gets inspected or emissions tested.
One last question, although the car runs great, I was checking some of the live functions (inputs to the ECU) and noticed oxygen sensor bank one keeps going from “lean to rich” constantly, I compared it to oxygen sensor bank two and it’s stable it doesn’t jump around as does number, should I replace it?.
Thanks,
Mario.
 
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