SOLVED: Parasitic Draw if Cabin Light Switch is in auto mode
SOLVED: Parasitic Draw if Cabin Light Switch is in auto mode
Hi Everyone,
So I been reading on this site about parasitic draws and haven't found anyone who has the problem similar to my issue. The battery goes dead overnight if I set the interior cabin light switch on the dash board to the centered setting - the setting where the lights turn on only when the doors are open and turn off when the doors are closed.
If I turn the switch to totally OFF position, there is no draw at all and she starts up lickety split. Also, I can hear a slight buzzing sound if I plug in the interior air quality vacuum hose electrical connector located in the left side of the driver on the trim covering under the steering column. So at first I thought it was this and I disconnected that air sensor. However, it will still zap the new battery if I set the cabin light switch to the normal automatic setting.
Any ideas and suggestions appreciated. I want to try to check the trunk and glove box light also but don't really know how to do that with those lids closed. Maybe a bore scope?
Thanks in advance Everyone.
VT
So I been reading on this site about parasitic draws and haven't found anyone who has the problem similar to my issue. The battery goes dead overnight if I set the interior cabin light switch on the dash board to the centered setting - the setting where the lights turn on only when the doors are open and turn off when the doors are closed.
If I turn the switch to totally OFF position, there is no draw at all and she starts up lickety split. Also, I can hear a slight buzzing sound if I plug in the interior air quality vacuum hose electrical connector located in the left side of the driver on the trim covering under the steering column. So at first I thought it was this and I disconnected that air sensor. However, it will still zap the new battery if I set the cabin light switch to the normal automatic setting.
Any ideas and suggestions appreciated. I want to try to check the trunk and glove box light also but don't really know how to do that with those lids closed. Maybe a bore scope?
Thanks in advance Everyone.
VT
Last edited by matreyia on Jul 17, 2022 4:51 PM, edited 1 time in total.
Re: Parasitic Draw if Cabin Light Switch is in auto mode
I've also experienced this in my 1988 528e... I haven't had a chance to look into it so I just keep it in the off position for now.
<edit>
I should note that it usually doesn't die overnight but within a few days if I don't drive it.
<edit>
I should note that it usually doesn't die overnight but within a few days if I don't drive it.
Re: Parasitic Draw if Cabin Light Switch is in auto mode
Good to know I'm not the only one. I guess I will have to get a borescope...need one Anyway.
Re: Parasitic Draw if Cabin Light Switch is in auto mode
If your car has the interior light delay then it could be the problem. They can go faulty and cause the current drain. On a RHD car it is on the right hand side of the car under the dash. Part no. 61 31 1 373 974 or 61 31 1 373 975. Tall black relay. If you remove it and check if there is still a current drain.
Re: Parasitic Draw if Cabin Light Switch is in auto mode
Good to know. I will definitely Check this. Thanks!
Re: Parasitic Draw if Cabin Light Switch is in auto mode
To check the boot light a small child is useful but I think nowadays that is probably not allowed!
If your phone can record video then put it on record and place in the boot or glove box to see if the light goes out.
If your phone can record video then put it on record and place in the boot or glove box to see if the light goes out.
Re: Parasitic Draw if Cabin Light Switch is in auto mode
Oh now I feel stupid. That's a great idea. Thanks for the suggestion!
Re: Parasitic Draw if Cabin Light Switch is in auto mode
Thanks for this! I was wondering where this relay might be... in my Alfa Romeo I used a jumper to bypass the relay as it quit working long ago.///M wrote: ↑Jun 25, 2022 5:05 AM If your car has the interior light delay then it could be the problem. They can go faulty and cause the current drain. On a RHD car it is on the right hand side of the car under the dash. Part no. 61 31 1 373 974 or 61 31 1 373 975. Tall black relay. If you remove it and check if there is still a current drain.
Re: Parasitic Draw if Cabin Light Switch is in auto mode
Just messed with my interior light relay. Found 5 cracked solder joints. Inspect yours closely or just bypass it.
SOLVED: Re: Parasitic Draw if Cabin Light Switch is in auto mode
Ok, if you got a parasitic draw and you replaced all your switches and all is in order... test your alternator. Turns out the alternator the vendor recommended was incorrect and had a rubber bushing isolating it from the ground to the chassis and thus caused the alternator not to charge AND the battery to drain when the car was both running or not running.
The incorrect alternator was fine, it just didn't have a negative chassis mount like the 1988 one does. Replaced it with a proper unit and battery is solid, after four days of testing with the switch in automatic door light mode.
The incorrect alternator was fine, it just didn't have a negative chassis mount like the 1988 one does. Replaced it with a proper unit and battery is solid, after four days of testing with the switch in automatic door light mode.
Re: SOLVED: Re: Parasitic Draw if Cabin Light Switch is in auto mode
Ah yes, sometimes the simple stuff gets you, I know I've been bitten before. On the alt, all it would have needed is a ~#8 ground cable between the body of the alternator, on one of the posts sticking out, to ground and it would have worked just fine.
Re: SOLVED: Parasitic Draw if Cabin Light Switch is in auto mode
Yeah, there was a negative bolt and nut on the alternator but I decided to trade for the proper model to keep wires to minimum and fidelity to the year.