# Micra 2015 doesn't start



## ukiyo (Jul 7, 2020)

I didn't find a Micra thread, but it is mostly a Versa...

Problem
Strong cranking, doesn't start. Radiator fan goes full blast while ignition is on. 
scanned; *U0100 lost communication (ECM A)*


Tried
removed heavy corrosion from the battery terminals
fuses checked 
grounds under hood cleaned and re-tightened, not sure if I need to try to redo the grounds inside the cabin.

I need help with figuring out what's what in this car... next thing that I think I should do is;
-Identify CAN BUS wires / test locations / common breakage points
-finding ECM relay
but I can't find anywhere which color the wires are or pins. I need help figuring this out to get my car back on the road.


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## rogoman (Dec 16, 2004)

The generic OBD trouble *code U0100* is a serious situation where the signals between the electronic control module (ECM) or the powertrain control module (PCM) and a particular module have been lost. There could also be a problem with the CAN bus wiring disrupting communications.

I couldn't find an FSM for your particular car but here's a link for 2007 - 2014 Versas which should help you:






Nissan Versa Service Repair Manuals


Nissan Versa Service Repair Manual PDF Free Download 2007 2008 2009 2010 2011 2012 2013 2014




diyservicemanuals.com


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## ukiyo (Jul 7, 2020)

rogoman said:


> The generic OBD trouble *code U0100* is a serious situation where the signals between the electronic control module (ECM) or the powertrain control module (PCM) and a particular module have been lost. There could also be a problem with the CAN bus wiring disrupting communications.
> 
> I couldn't find an FSM for your particular car but here's a link for 2007 - 2014 Versas which should help you:
> 
> ...


PCM would refer to the IPDM unit?

would you know how to decipher engine computer coding? I'm am planning to pick up an ECU to see if the communication will be restored. CURRENT ECU code nissan BEM332-300 A2 4728D (automatic tranny) this BEM332-300 A2 seems to be from 07+? I can only find 1 2014 Versa in my area, but there are many 12's .. not sure if the ECU would work from there as well since it is a BEM332-300 A2 code.


wiring appears to be OKAY for the CAN BUS








3


I feel like I'm left with ECU or IPDM 





this is likely what caused the issue, suspecting a surge during start up













Had a friend come by an scan it. It has many CAN BUS faults, is it possible the CAN BUS loop is broken by a faulty module and that is why I have this amount of CAN BUS faults? as I mentioned above, it would seem that all PINK/SKY-BLUE wires which I found to be CAN BUS related are in good shape


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## rogoman (Dec 16, 2004)

The nomenclature may be different but a Nissan IPDM is the same as a PCM. Since you're getting a P0100 fault code, it could point to a bad IPDM or a bad ECU. Once you clean up the heavily oxidized terminal connections, check the supply voltage to the ECU which should be 12v; If no voltage, consider replacing the IPDM first. If you replace the IPDM, you'll have to customize the settings to match your car.

Your question of "would you know how to decipher engine computer coding?" is no I don't know. Because first of all it's proprietary code that's not available to the public.


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## ukiyo (Jul 7, 2020)

rogoman said:


> The nomenclature may be different but a Nissan IPDM is the same as a PCM. Since you're getting a P0100 fault code, it could point to a bad IPDM or a bad ECU. Once you clean up the heavily oxidized terminal connections, check the supply voltage to the ECU which should be 12v; If no voltage, consider replacing the IPDM first. If you replace the IPDM, you'll have to customize the settings to match your car.
> 
> Your question of "would you know how to decipher engine computer coding?" is no I don't know. Because first of all it's proprietary code that's not available to the public.


Okay thank you for that information.

i will be going to a self serve scrap yard today. There is a 2014 versa, I hope it is automatic... I’ll pull both computers as well as get a good battery plate fuse box. Each module will be 40$Canadian which to me sounds like a good price to get answers


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## ukiyo (Jul 7, 2020)

rogoman said:


> The nomenclature may be different but a Nissan IPDM is the same as a PCM. Since you're getting a P0100 fault code, it could point to a bad IPDM or a bad ECU. Once you clean up the heavily oxidized terminal connections, check the supply voltage to the ECU which should be 12v; If no voltage, consider replacing the IPDM first. If you replace the IPDM, you'll have to customize the settings to match your car.
> 
> Your question of "would you know how to decipher engine computer coding?" is no I don't know. Because first of all it's proprietary code that's not available to the public.



I was able to get only the IPDM today, with the exact part number! Although... it did not repair the problem  

however I was swapping out fuses (because some were missing on the IPDM that I got) , and I found every fuse to be like this in the original IPDM











So i'll be going back to more wiring to check voltages as you suggested at the ECU harness


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## ukiyo (Jul 7, 2020)

rogoman said:


> The nomenclature may be different but a Nissan IPDM is the same as a PCM. Since you're getting a P0100 fault code, it could point to a bad IPDM or a bad ECU. Once you clean up the heavily oxidized terminal connections, check the supply voltage to the ECU which should be 12v; If no voltage, consider replacing the IPDM first. If you replace the IPDM, you'll have to customize the settings to match your car.
> 
> Your question of "would you know how to decipher engine computer coding?" is no I don't know. Because first of all it's proprietary code that's not available to the public.



*Would you be able to tell me.... Theoretically, *uncoded modules (used) plugged into the car should still communicate? Regardless of start condition.

*Immobilizer *on these cars.. Does it let the car start but then kills the fuel pump? Or is does it not even crank / spark


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## rogoman (Dec 16, 2004)

New un-flashed ECUs are like a brick, unable to do anything until an operating system is installed; the term used is called "flashing". It's just like your home PC; no OS - no booting up. For an ECU to communicate through a CAN (Controller Area Network), it has to be flashed with operating software which includes CAN driver code.

Used ECUs have ofcourse been flashed with software including CAN driver code, so to answer your question; if you install a used ECU, it should communicate out on the CAN.

The Immobilizer that's built into the steering column on these cars, disables the fuel pump and the ignition. On the earlier Nissans using a mechanical ignition key, the starter motor will still work but that's all. The Immobilizer that's built into the ECU on late model cars with a remote FOB will disable the fuel pump, ignition, and the starter motor.


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## ukiyo (Jul 7, 2020)

rogoman said:


> New un-flashed ECUs are like a brick, unable to do anything until an operating system is installed; the term used is called "flashing". It's just like your home PC; no OS - no booting up. For an ECU to communicate through a CAN (Controller Area Network), it has to be flashed with operating software which includes CAN driver code.
> 
> Used ECUs have ofcourse been flashed with software including CAN driver code, so to answer your question; if you install a used ECU, it should communicate out on the CAN.
> 
> The Immobilizer that's built into the steering column on these cars, disables the fuel pump and the ignition. On the earlier Nissans using a mechanical ignition key, the starter motor will still work but that's all. The Immobilizer that's built into the ECU on late model cars with a remote FOB will disable the fuel pump, ignition, and the starter motor.



I just did some more checking on the car.. and I'm leaning toward a bad ECU. From what I understand, these modules can be recoded by the dealer to fit my car? Now.. regardless of a Blank ECU and a USED ECU, same work has to go into it? (from programing point of view)

follow up question to that would be, do you think I can buy ANY* BEM332-300 A2 *module from the 14-17 years?


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## ukiyo (Jul 7, 2020)

rogoman said:


> New un-flashed ECUs are like a brick, unable to do anything until an operating system is installed; the term used is called "flashing". It's just like your home PC; no OS - no booting up. For an ECU to communicate through a CAN (Controller Area Network), it has to be flashed with operating software which includes CAN driver code.
> 
> Used ECUs have ofcourse been flashed with software including CAN driver code, so to answer your question; if you install a used ECU, it should communicate out on the CAN.
> 
> The Immobilizer that's built into the steering column on these cars, disables the fuel pump and the ignition. On the earlier Nissans using a mechanical ignition key, the starter motor will still work but that's all. The Immobilizer that's built into the ECU on late model cars with a remote FOB will disable the fuel pump, ignition, and the starter motor.


This is what I got yesterday, I haven't had the time to double check the gathered information as far as ECU wiring goes, but at least there is confirmation of voltage and ground being present at the ECU. Although I had trouble with the BROW (middle) connector. It almost seemed like some circuits were turning on/off while I was checking it, for which I went over it several times to try and rule out mistakes (what would happen is that sometimes I would get 3v readings and then 20 seconds later when I went to double check to write it down, it was gone. possible singals from other modules I guess since it's within the 5v range). If you could just have a look to see if anything stands out to you, thank you. I know that Modules/Sensors are 5v communicators, below I have some 7v readings to ground.












I also did a CAN bus test on the OBD II plug with a multimeter, here are the results. For some reason I got a 4.5v CAN bus total (should be 5v total between CAN - H and CAN - L), I'll take another reading later today to see if I made a mistake, otherwise CAN bus circuit checks out.


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