Having some odd issues with voltage that causes certain messages to pop on the dash even after the LMC5 install (including brown wire). If I have the car charged all night on the battery tender, no lights and everything is good. However, if I go anywhere and park, when I return and start her up, the pull key and wait 10 seconds message will reappear, which was happening all the time before the LMC5 install. There are also times where other messages will pop, such as low oil, service active handling, etc. but all of that goes away once I have the car charged over night. The shop that helps me with the car seems to think its a voltage issue, which is consistent with my reading of a bunch of posts on this issue on this forum. Brand new battery in December 2024. I also recently cleaned the grounds at the battery area, which didn't seem to do anything.

Any ideas of how I can trouble shoot this without having the shop spend a ton of time? Not a huge deal as I don't drive the car often - its more of a weekend toy. But would like to get it sorted and have time to do it during the evening. I did pick up a voltage meter and was going to do the parasitic drain tests but is there something else that may uncover the issue? Wondering if its the alternator as I don't understand why I would have a voltage drop after driving the car. Appreciate any direction.

 

I think your best bet is to take it to a trusted auto electric shop. They should be able to diagnose a parasitic drain quickly. If you don't know what you are doing..you can really chase your tail for days.

 

The first voltage measurement should be across the battery terminals with the car off, and then with the car running. You have to determine if the battery is being charged by the alternator. Your car probably doesn't have a current drain problem but rather a non operating charging system. Remove the alternator and have it tested, check the fuseable link on the wire that connects the alternator to the battery, it's located close to the starter solenoid, and lastly check the cable connections at the starter solenoid.

 

interesting thing is that if I don’t have the car on the battery tender, same thing will happen even if I don’t drive it.

 

So then your car must have a substantial current drain, but I would still insure that the charging system is ok. You have to connect a DVM with its settings and test leads configured to measure current and connect the meter in series with the negative battery cable and negative battery terminal. Acceptable current drain is approximately 25ma. I would still pull the alternator and have it tested as it can be one of the causes of excessive current drain.