This is going to be a long story but its the best way I can describe whats going on with my car and what ive already done/tried. I also want to be super specific because I havent found anything on the internet that comes close to the issues im having and every detail might help. So I bought this 2010 Nissan Maxima in the summer. I Needed a beater car to get to and from work. It had 350,000km on it at that time but it was in good shape and it ran good when I test drove it. The previous owner seemed like he took good care of it. He Had all the service records and repair receipts in a folder. It was the best looking thing on marketplace in the price range I was looking. It needed new brake pads and rotors but other than that it hasnt needed anything else and I've been driving over 60km per day with no issues. The car has been working the exact same since I bought it. Fast Forward to this past weekend (5 months later). I blew a brake flex line on the right rear wheel. So I fixed it myself, replaced the line, bled the brakes, and verified the brake fluid level was good. During the repair I found a pin hole the tire I had off. So I called a local shop that was 5 or 6 mins away from me and headed over there. I hit a red light about half way there and the car seemed to have gone into limp mode. All dash warning lights came on at once, RPM's wouldn't go over 2000 and couldn't drive faster then 50kmh. Got it to the tire shop and shut it off. Tire guy started it, brought it in, fixed the tire and brought it out. No issues. I left the tire shop pulled onto the main road and drove away, again no issues. Once I Got to the first red light 2 mins away, the car went into limp mode after the complete stop. So I shut it off and turned it back on. It was normal again so I drove for about 10 more minutes, no issues. Even had to slow down to take turns but no complete stops. once I pulled up to a stop sign and came to a complete stop the dash lights all came up again and it was back in limp mode. I was in traffic so I tried to put my hazard lights on but they weren't working. No lights outside and no indicators on the dash, I even tried just using the signals by themselves but they didnt work either. I pulled over and tried turning the car off. When i pushed the off button the speedo and tach both went to 0 and the gear indicator on the dash that usually says wether the Trans is in P, D ,R or N was blank but the engine was still running. I tried again to shut it off but it wouldn't. Tried putting it in gear and back in park but it still wasnt shutting off and the indicator was still blank. So I limped it all the way home where I had to pull the fuel pump fuse under the hood and then disconnect the negative cable on the battery to finally get it shut off. I left the battery disconnected and went in to eat supper so the ECM could reset. After supper I went back and reconnected the battery and tried starting the car. The lights came on and the dash lit up like normal but it wouldn't start, no crank at all. And I just recently replaced the key fob battery so I knew that wasnt the issue. I thought maybe the car battery is bad so I used my other rig for a boost. After a few mins i was able to get it cranking but it would only crank for a few seconds and wasnt starting.

The next day comes and I go out and get a fresh new battery and put it in the car. Tried starting it and now it would crank as long as I held the button but wasn't firing up. I checked the fuel pump, disconnected the plug and reconnected it checking for pin damage. All looked OK. I Turned the car on and off accessory mode to prime the fuel. Pressed the brake pedal and the start button and it fired up right away. No dash warning lights and tach was reading RPM's again so I took it around the block, quick drive but no problems. Figured it was all behind me now. The car sat for 1 whole day after that, untouched. Now its Monday morning I'm getting ready to leave for work. I run outside and start up the car to get it warmed up because it is currently winter time. So about 10mins after starting it, I get back out the car and pull out of my driveway to then realize the car is in limp mode doing the same weird stuff... the tach and speedo are reading 0, no gear indicator, no signals and it won't shut off when I push the button. So I disconnect the battery and instead of pulling the fuel pump fuse I pulled a big green fuse that according to the diagram controls 3 different functions. One of the fucntions was labeled IGN so now it would shut the car down without running the engine dry of fuel by killing the fuel pump. So I reconnected the battery and tried starting it. The dash would light up and everything looked like it was working but it wouldn't crank and it also wouldnt turn back off. So I disconnected the battery and left it. Took a different rig to work and that evening I brought home a OBD 2 scanner and some electrical testing tools. Got to the car and connected the battery and then tried starting it. It fired up right away like there wa never an issue. I let it idle for a bit while I Checked all the fuses under the dash and under the hood. All okay. Checked codes. No active codes. So I took it or a long test drive. Hitting multiple stop signs and red lights, no issues. Got back home shut the car off normally and went in for the night. Next morning. Went out and started the car and let it warm up for 5 or 6 mins. Left the house headed for work, hit multiple stop signs and multiple red lights, no issues. Stopped at a store for snacks and left the car running. Once I got back out to the car it was already back in limp mode doing the same weird stuff as before. So again I limped it home and had to pull the fuse and disconnect the battery to get it to shut off. I had to take the wife's rig to work again and I didnt have it in me to look at the car again tonight, so I made this post instead. hoping someone out there has dealt with this or knows where to start looking?

 

This appears to be an intermittent electrical issue. The IPDM is probably malfunctioning. You said you had a scan tool. Does it have the capability to scan the IPDM? It could also be that some critter has gnawed away at some cables in the engine bay.