Need help with ECU P0603 code
 

I'm having some problems with the ECU on my 07 350z. Every time I turn the ignition off, the car loses its memory in the ECU. It always has a P0603 code pending now. I think this happened because I took apart my center dash off and left my headunit loose and not bolted in. I drove around and my head unit stopped working. I found out that I blew the radio fuse (in the fuse box by the battery). Replaced the fuse and the radio worked again. The car then threw a P0603 code and SES light right after but went away after 2 or 3 drives.

Now every time I shut the ignition the car resets the ECU and I get a pending P0603 code. With an OBD scanner the car has 3 out of 6 readiness monitors ready when I first start the car. After I drive around for 20 miles 5 out of the 6 monitors are ready, but as soon as I turn the ignition off only 3 out of the 6 monitors are ready again. The car still drives fine, it just wont store any memory so I can't complete the readiness monitors needed for the smog check. What are the chances I fried the ECU?

Can somebody lead me in the right direction? I'm thinking of getting a shop to use Consult to reflash my ecu.(My ecu is completely stock never added any type of tunes). If that doesn't work I'm thinking of picking up an used ECU and having the dealer reprogram my keys to match.

Have you checked the battery? That seems to be the first thing people check after googling around. Though I assume you have already googled around.
I have an '04 and the service manual for it, but it seems that code was added starting in 2006.

According to the FSM, the power supply back-up circuit is open or shorted, or it's a bad ECM.

Here's the FSM portion for this code. Maybe it will help.


https://cimg4.ibsrv.net/gimg/my350z....7de722ac6b.png
https://cimg6.ibsrv.net/gimg/my350z....420ead524d.png
https://cimg7.ibsrv.net/gimg/my350z....8f6cff36cb.png
https://cimg9.ibsrv.net/gimg/my350z....594e705111.png

Thanks, for the service manual post. I checked the fuse 15A fuse its still good. I'll have to trace the pink wire from the 15A fuse to pin 93 of the ECU to see if there's a problem with the wire before messing with the actual ecu.

did you ever find a fix for this issue?