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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E30 (1982 - 1993)

E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 10-11-2012, 02:10 PM
Bimmerkid325i Bimmerkid325i is offline
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1991 325i electrical question

I have a 91 325i and am getting a battery drain that kills the battery in about a day and a half of non-use. I have my multimeter to track down the drain the the fuse 21 circuit. I've tried ruling out specific components controlled by the fuse 21 (7.5 amp). Has anyone had this problem? Any suggestions where the common problem might be? Thanks!
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  #2  
Old 10-11-2012, 08:08 PM
BMWEnthus BMWEnthus is offline
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What componets are the 21 controlling? Have you check for a short?

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  #3  
Old 10-12-2012, 01:36 AM
Billwill Billwill is offline
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Trunk light and dome light are controlled by that fuse...trunk light is the usual suspect.

Get someone small to climb in the trunk and check if light goes out when trunk is closed...not for claustrophobic people.

Or simply actuate the trunk switch to check if the light goes out.
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  #4  
Old 10-12-2012, 08:10 AM
Bimmerkid325i Bimmerkid325i is offline
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Quote:
Originally Posted by Billwill View Post
Trunk light and dome light are controlled by that fuse...trunk light is the usual suspect.

Get someone small to climb in the trunk and check if light goes out when trunk is closed...not for claustrophobic people.

Or simply actuate the trunk switch to check if the light goes out.
I believe the dome light is only in the convertible models. My 325i only has the lights over the driver and passenger heads above the doors.

I popped out the the trunk light and unplugged it at the connector. Then checked for current drawing off the battery. Still had a draw so concluded it wasn't the truck light. Could I still be mistaken? How would I disconnect it completely if that is the problem? Just take out the bulb? Thanks! And the trunk switch you are referring to is the one located on the interior lip of the truck itself? Like the one on the driver door that turns off the chime and interior lights?
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  #5  
Old 10-12-2012, 08:14 AM
Bimmerkid325i Bimmerkid325i is offline
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Quote:
Originally Posted by BMWEnthus View Post
What componets are the 21 controlling? Have you check for a short?

Sent from my PG06100 using Bimmer App
Here's what I found for the fuse 21 description. Also have a wiring diagram (at home at the moment) that has this information. I will double check and get back later today. Thanks!

21 7.5 Glovebox light
Flashlight
Ignition Key/Seat Belt warning
Interior Lights
Radio Memory
Trunk Light
Active Check Control
Service Interval Indicator
OBC
Fuel deliveryTachom eter/Fuel Economy Gauge
Digital Clock
Multi Function Clock
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  #6  
Old 10-12-2012, 08:19 AM
BMWEnthus BMWEnthus is offline
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Is your radio stock? Alot of times in after market people wire wrong and it causes problems

I looked at the fence said i've never climbed a fence that high. And woke up at home
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  #7  
Old 10-12-2012, 10:52 AM
Bimmerkid325i Bimmerkid325i is offline
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Quote:
Originally Posted by BMWEnthus View Post
Is your radio stock? Alot of times in after market people wire wrong and it causes problems

I looked at the fence said i've never climbed a fence that high. And woke up at home
Radio is not stock but was install a long time ago and has never had any problems. Could it possibly cause a problem this far out?
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  #8  
Old 10-12-2012, 11:03 AM
BMWEnthus BMWEnthus is offline
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I highly doubt it unless the wires came loose or your unit is going bad but since it not im gonna say no have you checked your battery terminal mine was corroded which caused it to drain over time

I looked at the fence said i've never climbed a fence that high. And woke up at home
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  #9  
Old 10-12-2012, 04:57 PM
Bimmerkid325i Bimmerkid325i is offline
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Originally Posted by BMWEnthus View Post
I highly doubt it unless the wires came loose or your unit is going bad but since it not im gonna say no have you checked your battery terminal mine was corroded which caused it to drain over time

I looked at the fence said i've never climbed a fence that high. And woke up at home
There was a small small amount of corrosion buildup on the positive terminal. Would there possibly be corrosion on the wire going up towards the front of the vehicle from the truck?
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  #10  
Old 10-12-2012, 05:03 PM
BMWEnthus BMWEnthus is offline
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I dont think so since its insulated but my negative cable where it bolts to the car was completely corroded but that killed my battery after starting the car bmwfatherfigure is way better and downhiller as well they may be able to pinpoint it for you
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  #11  
Old 10-12-2012, 05:56 PM
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BMWFatherFigure BMWFatherFigure is offline
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Thanks for the good word, BMWEnthus. As the problem seems to be related to Fuse 21 only I would be going for everything connected to that circuit big time. Do you turn the radio down or fully off? If you used to turn it off but now only down B4 taking the key out it could be that the radio was put on permanent power in error - just a thought. I guess that if fuse 21 is pulled the battery stays good for a week (or at least several days)? If this is the case you will have to isolate the items on the fuse one at at time. Slow I know but when you find the faulty unit there will be no doubt and it is cost free.

Battery terminal/wire and connection corrosion should be fixed asap. A strong solution of bi carbonate of soda in hot water will nuturalise the acid growths and then clean and test/inspect all joints, terminals and earths.

Globe/bulb removal will stop any drain from a light, again check for corrosion. How is your charging voltage?
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  #12  
Old 10-13-2012, 11:05 AM
Bimmerkid325i Bimmerkid325i is offline
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Quote:
Originally Posted by BMWFatherFigure View Post
Thanks for the good word, BMWEnthus. As the problem seems to be related to Fuse 21 only I would be going for everything connected to that circuit big time. Do you turn the radio down or fully off? If you used to turn it off but now only down B4 taking the key out it could be that the radio was put on permanent power in error - just a thought. I guess that if fuse 21 is pulled the battery stays good for a week (or at least several days)? If this is the case you will have to isolate the items on the fuse one at at time. Slow I know but when you find the faulty unit there will be no doubt and it is cost free.

Battery terminal/wire and connection corrosion should be fixed asap. A strong solution of bi carbonate of soda in hot water will nuturalise the acid growths and then clean and test/inspect all joints, terminals and earths.

Globe/bulb removal will stop any drain from a light, again check for corrosion. How is your charging voltage?
The problem was notice and tracked down this last Tuesday 10/9/12 and it hasn't been drained since I pulled fuse 21.

I'll be able to work on it more tomorrow. I'm working almost every day so my free time to spend on it is limited. I will keep you updated. As far as I know I have good charging (since its been driven every day since diagnosis and no draining or dead battery) but I will check tomorrow and get a definite figure on the charging voltage. Ive unplugged (by the connector) both overhead lights, truck light, active check control (overhead), glove box light, and radio faceplate. All these didn't cause the battery drain because there was little to no change in the amount of draining. When I removed the radio faceplate I noticed that the drain was less then when it was on. Meaning? I am going to pull off the digital clock tomorrow to check that. The flashlight connection in the glovebox shouldn't be a problem I'd think because I don't have the flashlight attached. :/ next would be to pull off the cluster and unplug the connection to the fuel economy gauge and service interval indicator. Also where is the ignition key/seat belt warning? Anything else on this circuit I should check. I have an electrical diagram in the car (not with me right now) and will double check myself. Thank you for all the help!!
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  #13  
Old 10-13-2012, 11:17 AM
BMWEnthus BMWEnthus is offline
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I know there is a seatbelt indicator on the panel above the mirror as far as the faceplate being off does the drain reduce dramatically/stop. Or does it just slow it down? I cant help but think there is a short let me know what you find when you keep looking i cant help but think there is a short draining the battery

This captain goes down with the ship
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  #14  
Old 10-13-2012, 11:24 AM
BMWEnthus BMWEnthus is offline
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Bmwfatherfigure what about the fuse block itself do you think there could be an error there? Just a thought but as he said none of those caused it, it seems like its coming from somewhere before it hits those items as removing them didnt stop it so it would seem the power is still going somewhere

This captain goes down with the ship
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  #15  
Old 10-13-2012, 12:09 PM
BMWEnthus BMWEnthus is offline
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Just thought of this! When you turn your car off does the stereo shut off? Now the panel may seem off but look for dim light as the stereo has a memory wire 12v always powered and an on wire which only has power with the ingintion on some people have in fact wire these backwards making the memory wire the power wire which means the unit never shuts off

This captain goes down with the ship
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  #16  
Old 10-13-2012, 12:54 PM
Bimmerkid325i Bimmerkid325i is offline
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Quote:
Originally Posted by BMWEnthus View Post
Bmwfatherfigure what about the fuse block itself do you think there could be an error there? Just a thought but as he said none of those caused it, it seems like its coming from somewhere before it hits those items as removing them didnt stop it so it would seem the power is still going somewhere

This captain goes down with the ship
The idea that there could be a short at the fuse box makes sense. Possibly in the inside? Ill research/take a look.

When I unplugged the previously stated components it only caused the battery to drain slower, still a drain just not as much. Ex) with everything plugged in I got a 0.59 drain and with radio faceplate off I got a 0.38 (I trying to remember those numbers from a few days ago but the point is still the same, still a drain just less of it when units unplugged).

Also the cd player has been installed for years and had never cause a drain before so it seems unlikely that those two wires would be switched and causing a drain now. But I'll look into that too.
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  #17  
Old 10-13-2012, 12:55 PM
Bimmerkid325i Bimmerkid325i is offline
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I agree that a short sounds more like the problem but it's just a matter of slowly working through the system :/
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  #18  
Old 10-13-2012, 01:04 PM
BMWEnthus BMWEnthus is offline
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Thats true about it being on for so long it makes sense but i just cant think of a reason why the faceplate being off would lesson the problem if i were you i would replace the fuse and remove the stereo completely (given you know how to rewire it) and then check it seeing how the head unit without the faceplate would lower it i would check that first

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  #19  
Old 10-14-2012, 09:04 PM
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BMWFatherFigure BMWFatherFigure is offline
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Presuming the battery terminals are fixed now - check the base of the fuse box. I don't expect you will find problems in there unless some PO has worked his 'magic'. I guess you know what to look for so I won't insult. Clock drain is minimal - like a digital watch across the battery (feel free to test). Have you quantified the drain current? You could try connecting an amp meter and checking when the drain current stops. Start that test by taking out all roof and boot light globes B4 you connect up. Start with high amp setting and work your way down. When you remove offending unit the drain current will drop.
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  #20  
Old 10-15-2012, 04:00 AM
Billwill Billwill is offline
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The problem with a current drain such as you are having is that often it does not help removing for instance the bulb from the trunk......the problem may be that the leads going to the bulb in the trunk may be partially shorting to ground or shorting to another cable inside the harness...removing the bulb at the end will not change matters much.

You need to be somewhat brutal here....as stated put an Ammeter in series with the battery and note current drawn.
Pull fuse 21 out...current drops significantly.

Now you have to trace where the output of fuse 21 actually goes....according to my circuit diagram it is a Red/Green wire which then branches out to seven other locations...all using Red/Green wires.

These locations are:
Instrument cluster pin A2
Trunk light
Radio
Chime module
Auto charge flashlight
Left dome light
Right dome light

You need to find where these wires branch off from the main lead and on by one physically cut them off at the branch with a wire cutter until you find the one causing the problem.

You then re-join the innocent wires and insulate...preferably with shrink-tubing insulation.

The faulty wire you can try to physically trace to see if it is fraying somewhere but if it is inside a thick loom full of other wires it is best to cut that wire off at both ends and lay a new wire to replace it.

I have had to do this procedure about 6 times on a Jeep that I own due to accident damage causing several wires inside a large loom to have partial shorts to ground or partial shorts to other wires lying next to them in the loom.

Last edited by Billwill; 10-15-2012 at 04:02 AM.
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  #21  
Old 10-15-2012, 08:05 AM
Billwill Billwill is offline
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First thing to do though is to remove the radio completely before cutting wires as above!

Edit to add: Do you perhaps have an aftermarket alarm/immobilisor connected on that same fuse circuit?

If so, might be worth disconnecting it.

Last edited by Billwill; 10-15-2012 at 11:41 PM.
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  #22  
Old 10-16-2012, 01:44 AM
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BMWFatherFigure BMWFatherFigure is offline
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The worst people to follow into a dashboard are radio fitters; alarm/immobiliser fitters; plumbers.
I would consider cutting wires as a LAST resort. Big plus on corrosion though - be very aware of that.
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Last edited by BMWFatherFigure; 10-16-2012 at 01:46 AM.
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  #23  
Old 11-29-2012, 02:21 PM
Bimmerkid325i Bimmerkid325i is offline
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Determined to be the main relay. Was stuck on and drawing 1.2 amps. Finally taken care of.
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  #24  
Old 11-30-2012, 07:58 AM
WickedFast.Inc WickedFast.Inc is offline
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