[swollix]

It's been one problem after the next with this car, haven't had it be error free longer than two weeks and I've had it four months. Anyways the other night I noticed the start/stop button was on in the dark. I went somewhere and came back five hours later and it was still on. I tried starting the car and it wouldn't start. I left the battery on a tender all night and it didn't even have enough power to unlock the car. I replaced the battery today and everything seemed fine, but I went outside just now to check and the start/stop button is still illuminated. The only aftermarket electronics are LED angel eyes and a trunk subwoofer that has been installed since I bought the car. It has not caused issue before... The only other recent work has been a fuel injector, intake valve cleaning, and lowering springs. While injector was being coded, we diagnosed a faulty LPFP... only error code was 29dc for cylinder shutoff, could that cause it?

What should I check first!?

[lookalikehuuh]

The LED that lights up the start/stop button on my car is always on even after i leave the car. I also always have the "P" indicator on since my car is an automatic even after it sits for a long time.

So far hasn't been a problem in a few years that I've owned the car. Still on the same battery. Maybe its just normal operation?

[pmmcbl]

The led and the p for the auto box will stay for for a little while once you have locked the car. They will go off after a minute or so. If after 30 minutes they are still on then yea you have a problem.

[GoRomeo]

Start/stop button should only stay ON for about 2 hrs if you dont open doors etc. To make sure car goes to sleep sooner make sure u lock the car. This way it goes to sleep right away. Maybe is your battery the whole issue. How old is the battery? Did u replace it yourself? These cars react funny when battery is weak.

[swollix]

Car is manual,no shifter light. I always lock the doors as I park it outside. I have never noticed the light on before. I drive the car 100 miles/ day so it's not that either.

[08TUNDRA]

Its supposed to be 16 mintues for the ecu to sleep in normal conditions. So lock the car and check if in 20 minutes the light is still on you got a problem. Have you been getting the increased batter discharge light on startup?

[swollix]

Originally Posted by dmikhael619

Its supposed to be 16 mintues for the ecu to sleep in normal conditions. So lock the car and check if in 20 minutes the light is still on you got a problem. Have you been getting the increased batter discharge light on startup?

Car has been sitting all night, and the light is still on. It's been on a battery tender so no discharge light when I started it.

[sebaNYC]

did you install another or new Amp for the subwoofer? if so, thats draining your battery.

it happened to me, the amp didnt let the car go to sleep mode and was on all the time

[///Mposter]

I would disconnect the power to the subwoofer and see if after 20 min it turns off. Maybe the source they tapped is incorrect or maybe it is sensing a drain and is staying on. Other things to check would be the door close sensors/ switch . Maybe it thinks the trunk or door is open expecting a person to re-enter.

Also if you have comfort access, then make sure you don't have the spare Fob in the car glove compartment or workout bag, or hanging near the car in the garage.

[kiel_dafo_kenyg_as]

On E38 series once the rechargeable battery of the flashlight in the glove compartment went bad it drained the car battery.
If the car doesn't go to sleep it draws a lot of current

[swollix]

I will disconnect the subwoofer, it's never been an issue before though. How do I check the door and trunk sensors? No comfort access. I'll take out the glovebox flashlight too.

[NOITALL]

Disconnecting items isn't going to solve it; the car should cut the power to them.

Have you checked all fuses and relays? I'd start there.

[fazman]

Originally Posted by swollix

It's been one problem after the next with this car, haven't had it be error free longer than two weeks and I've had it four months. Anyways the other night I noticed the start/stop button was on in the dark. I went somewhere and came back five hours later and it was still on. I tried starting the car and it wouldn't start. I left the battery on a tender all night and it didn't even have enough power to unlock the car. I replaced the battery today and everything seemed fine, but I went outside just now to check and the start/stop button is still illuminated. The only aftermarket electronics are LED angel eyes and a trunk subwoofer that has been installed since I bought the car. It has not caused issue before... The only other recent work has been a fuel injector, intake valve cleaning, and lowering springs. While injector was being coded, we diagnosed a faulty LPFP... only error code was 29dc for cylinder shutoff, could that cause it?

What should I check first!?

Are you sure you have all the latest software updates for the car/modules? I'm not sure who can do this for you other than the dealership?? This sounds more like a software issue.

[swollix]

Attached multimeter between negative terminal and negative wire... hmm

[swollix]

Since it's not pulling but 1.5 milli amps with the negative cable off that could only mean it was the IBS. I disconnected the IBS and locked the car and sure enough the start button turned off after approximately 2 minutes. Now if only the cable wasn't $200....

[MARKARMF]

I've now just started having this issue with my E90, I stripped the start/stop button and took the LED light off the circuit board, charged the battery up and all is well