My g37 has been having this issue where it will go into limp mode every so often and the battery tends to die when it does. When it happens I cannot put the car in reverse and when I put the car in park it says it is still in drive. I occasionally get the battery light and the e-brake light on the dash even when I dont have the e-brake on and the battery gets right off the charger. Even when it goes into limp mode and I put it in park, the car will eventually just die and turn off. Everything just shuts off. Yall have any idea whats going on? The alternator is in good health according to multiple

shops and I just got a new battery.

 

Who tested the alternator and, more importantly, how did they test it? What was the charging voltage at idle? Under full load?

More often than not when you have the battery light and the brake light on at the same time you have a charging issue. This means that the car is running (likely) solely on battery power and the car is telling you to "get somewhere safe and stop, soon!"

Simple test. With the engine running (wearing gloves) disconnect the NEGATIVE battery cable. If the car shuts off or if the engine starts to "sputter," the alternator is shot. If the car still runs/ no change, then you have a separate issue.

Keep in mind a alternator can die a slow death and drain a good battery- even when the car is completely off.