Hi, looking for help on my infiniti. Bought a car as a project and the issues it's having is losing all throttle response, and throwing every light on the dash while also reving and downreving the engine on its own. Car drives/shifts with no issue when problem isn't there. Any help would be amazing. Battery has no parasitic draw but is smaller than normal group size (450-550 CCA) alternator was replaced by previous owner(deffinetly did happen)

Codes are: P0603 (ecm backup/ circut) p100a and p100b (VVE/L system bank 1 and 2) P0500 (VSS) P0732 (a/t 2nd gear function)

 

Sounds like you have either a damaged wire somewhere causing an intermittent short circuit or a non-genuine sensor sending incorrect data. I’d check/clean the 2 MAF sensors, make sure the throttle bodies are actuating in accordance to the pedal and check/clean the MAP sensor on top of the intake plenum.

make sure you’re looking at the wiring leading to each sensor too. I’ve had a Chevy Impala that was totaled out by wiring damage caused by rodents

 

I also wanted to mention cleaning the 2 throttle bodies as well.

Take a 5mm Allen key and remove the bolts to check behind the butterfly (the carbon doesn’t accumulate on the front).

most OEMs don’t have a service interval for cleaning the throttle body, but they definitely cake up with carbon as the car racks up the miles and can cause a lot of power loss & hesitation.

 

There are no throttlePS or maf/map codes. I'll still clean them out, check wiring and see if that works

 

yeah, those are just commonly over-looked maintenance items that effect throttle response. Although if you know for a fact that the current battery is too small, than i'd get that replaced asap. Even though the battery installed now is enough to turn over the car, it sounds like its not enough to keep up with the car's electrical demand of a steady 13.5 to 14.5 volts while it's running and causing intermittent issues.