Ok, things going from Bad to very Worse. Per my previous posts my Radio/NAV/Display stopped working properly. The great help here, and then my mechanic, felt it was AV control hardware issue that needed replacement. Yesterday, after a week of this, the backup camera wouldn’t come on for a minute (like the the radio station and AC), and the sonar stopped. I unhooked the battery yesterday, to see if it would help. Engine started this AM. Now I get KEY SYSTEM ERROR, car weakly tries to turnover if at all, no start. Have continuous key system error. No other warnings. When it tries to start headlights go out, then immediately come back on. Doesn’t seem like dead battery as lights keep coming back. Starting to think something really bad is going on. HELP!! Could this be from taking battery cable off? Somehow related to the AV control?? Battery or other issue. AMAZINGLY, the display, radio, and Nav are working for the first time in 40+ hours, although it keeps booting to Nav screen and not last setting. HELP!!

Maybe you got a bad BCM

That’s what I’m afraid of. Is it possible it’s from a weak battery, even though headlights are normal brightness except dark when trying to start. I don’t hear the starter, lots of dashboard clicking and now Key System and Headlight warnings. It was slightly sluggish start in the Am, which was new. May need a wallet biopsy for this one, and the radio issues.

Firstly, what you just described is a dead battery. Try jump the car. If it starts with a jumper box, then change the battery. You probably never stopped off the water in the battery or left something on overnight. If it starts and turns off shortly after, then probably a bad alternator

You could also take the battery to AutoZone and have it tested and charged. If you do this and the battery light is on when you start, then your alternator is dead.

Either case, I would change the battery since it's probably beyond saving.

Tbh a bad alternator might explain all your problems. These need cars don't like funky voltage.

Great thanks. I was hitting the key fob and starting it in the garage like 100 times in the past week trying to get the RADIO/NAV to reboot like we discussed the other day. I put it on my trickle charger for a minute 2 days ago to check the battery, and it read 95%. Not sure that’s accurate???? given all the starts, no driving and the slightly sluggish start. I’ll get a new battery tomorrow. The weirdest thing is the NAV/radio working perfectly the first attempted start (after many days not working) now it’s not working again. Maybe some voltage change w low battery defibrillated it temporarily. Thanks for replies.

If replacing the battery, I STRONGLY recommend one of the newer AGM (antiglass mat) maintenance-free ones. I personally prefer Die Hards from Advance Auto Parts (used to be a Sears only line but it came back a couple of years ago). I believe our size is 24F but please confirm.

Thanks Ilya.

Definitely get a new agm battery (sometimes called agm2) and do the brownie mod so your car doesn't kill the battery. The car won't start charging until you drive 7 miles, which you didn't do in the garage so the battery is drained way too low.

Btw, agm batteries aren't cheap. Maybe 3x the cost of lead acid. And don't install it before doing the brownie mod or else the car will kill the battery.

Brownie mod: howto-disable-ecm-controlled-alternator ... l#p6792009

Interesting Yoda, never heard of that but makes sense. I haven’t driven over 4 miles (8 round with stop) in almost 3 months. Averaging 20 miles/ week. If that brownie mod post alternator mileage kick in is accurate, I know for a fact I have not driven far enough in over 2 months to trigger it. That said, the car is 5 years old, I’ve had a month here and there with similar driving. Yesterday was the first time it ever had sluggish start in Am, then dead at night. In a few hours I’ll go to where it’s stuck and hopefully charger will get it going, and that Key Warning won’t be a problem.

Follow up: It took 6 start attempts with charger. Finally turned over on #6. The KEY SYSTEM light remains on all the time. I disconnected the charger, and car started immediately. I then turned headlights on (normal brightness), and car still started immediately. We’re changing out the battery as recommended here. I hope it’s a bad cell or something. I don’t have much experience, but I’ve never had a bad battery where it takes so many starts on a charger, yet a minute later it’s able to start with lights on. Anyone see that?

That sounds more like a bum connection than a bum battery, although occasionally batteries with bad post attachments internally can behave that way.

VStar650CL wrote: ↑

Wed Jan 18, 2023 4:02 pm

That sounds more like a bum connection than a bum battery, although occasionally batteries with bad post attachments internally can behave that way.

Thanks. Wow. I hope not connection. The KEY SYSTEM warning started with the NO start last night, and still is on even though car is starting again. Last night the Headlight warning was also on, that went away. My fear is that it’s a new intermittent issue caused or related to the known AV control module problem, or BCM or other.

GOOD NEWS so far at shop. Testing showed very bad battery. We’ll see how it goes later today and tomorrow with the new one in soon. Thanks all for help.

Ok so battery seems to be working great, the KEY SYSTEM code was cleared, and starting perfectly. Waiting for EBAY AV Control module, hoping to resuscitate my radio/Nav/Bluetooth next week without needing a new part mortgage. Thanks again.

Glad to hear some good news. you should really do the brownie mod.

Yoda's Master wrote: ↑

Thu Jan 19, 2023 7:23 pm

Glad to hear some good news. you should really do the brownie mod.

Thanks. I mentioned it to my mechanic. We’ll revisit it in the next 2 weeks when we throw the Hail Mary Av Control module in and hope we’re turning the corner on out of warranty land mines. He did put in the best AGM type battery available here quickly in the middle of the Pacific. It’s bigger than the stock one.

make sure you buy a agm compatible battery tender and use it at least a weekend every month till u get the brownie mod done.

what battery?

It’s a NAPA the Legend Premium AGM. Only auto parts store within an hour, and needed it ASAP. THANKS for advice.