[danzomatic]

I have a 2001 Sentra GXE automatic. This thing is eating ECMs. There was an ECM recall (#50659) that had to do with a foam mat insert in the ECM box. The dealer says they performed the necessary repairs for this recall (taking out the foam mat) but some time later my ECM went bad and when I went to replace it, the foam mat was still there. I pleaded my case, but to no avail. Fast forward another 5 years to the present and my ECM (#2 for the car) just went out again. If I replace it, this will be the car’s third ECM (and they’re not cheap). I searched eBay, etc. but haven’t been able to find a cheap replacement. What I’m really looking for is a schematic of the ECM itself (not the vehicle’s electrical system or ECM pin out). I have an electrical engineering background and if I can isolate what components are doing what on the circuit, I can begin to check for failed resistors, caps, etc. As it is the circuit is too complicated to poke around without a schematic. Any help? I’ve done a bunch of searches and it seems like others have had similar problems. It doesn’t help that Nissan’s electronics are so much more expensive compared to Honda and Toyota. ECM p/n: 23710-5M107 Thanks in advance,

 

[i68k]

im not sure you will be able to find a schematic of the ecu itself, as this would be protected information from nissan, copyrights, patents, etc, but not to say some aftermarket company hasnt already cracked them the fsm contains a schematic of the entire vehicle, but im not sure that will help you entirely. you can run thru the fsm and check voltages, resistance, and continuity for all the pins in the ecu harness, this way you can make sure its not the ecu fault it is failing. im not exactly sure on the ecu parts numbers, but from your post, it looks like you need one of the 5M ecus, im not sure how many version of 5M there are. you maybe able to find one in the junkyard for a lot less than new. try car-part.com, also the fsm you can download for free around here somewhere. try nicoclub.com/fsm

P1320 NISSAN - Ignition Signal
P0301 NISSAN - Cylinder 1 Misfire
the misfire most likely was caused by the first code, the problem with your ignition system. the main question is, how do you know the ecu has failed....? normally on ecu failure, you cant do the pedal dance, or retrieve ses codes, most of the time the motor will not run. with your current post, i would first assume you have grounding issues, which commonly fry the ecu. this happens when the battery terminals, or other wires are shorting or not getting sufficient ground contact. the common scenario is when the battery ground becomes and looses contact, then the coilpacks become the common grounding point, which can ruin the coils and the ignition system (p1320). also, your cam&crank sensors could produce a similar scenario by mis-timing and misfiring. so i would make sure your battery, electrical connections, and charging system are working properly, if you can start the motor, check your voltage motor on&off. after this, you should start checking your ecu harness.

 

[danzomatic]

Thanks for responding i68k. I have the FSM and have gone through all of the checks in the trouble trees. When everything was pointing to the ECU, I took it in to the dealer to let them diagnosis with Consult II etc. without telling them my own findings. They too concluded it was the ECM. I agree with your point on the grounds. Checking those too and will re-check them before installing the new ECM. The ECM part number is pretty specific. I don't think you can swap it with any of the other "5M" versions. The car starts, runs, etc. It's just misfiring on cyl 1 (as the DTCs) indicate. This function pins out to pin #38 on the ECM connector. The goal now is to trace that circuit on the board and figure out what's "fried" ... easier said than done.

 

[danzomatic]

Still looking for insight. I have 2 ECMs needing repair. One keeps throwing a MAF code and and sending the car into limp mode. The other is the misfire on cyl 1. A lot of searching on the web indicates that these ECMs are prone to failure. There's even a niche market on eBay for repairing them. I wish I knew which resistors, caps, diodes, etc. were the ones that typically fail... I replace them myself.

 

[i68k]

send a message to shortcut10, hes probably the only person i can think of that maybe able to help you out, he works at a dealership. you can try him at b15u.com as well. otherwise you can try contacting on of those companies repairing the ecu on ebay.