Obc draining my battery?

[arty818]

Hello, my car is a 1986 325e Auto. The problem im having recently is my battery drains after about 10-12 hours of being turned off. It goes from 12.62v - 11.89v in 10 hours of sitting off. So i hook up a multimeter and i see i have a 173.3mA drain. I start pulling fuses and fuse 21 is drawing 33mA and fuse 27 is drawing 140mA both combined are the only drains on my battery, every other fuse combined = .1mA. I checked the fuse diagram and here is what i got.

21 = 7.5A - Interior Lights - radio memor - instrument panel lights
- glove box - rechargebale flashlight - clock - trunk light
- seat belt gong - ignition key warning gong - **OBC**

27 = 30A - Central locking system - door lock heating? - anti-theft -
- **OBC**

How do i tell which OBC this is? ABS, Idle Control, Motronic ECU? if it is one of these how do i test if its bad or needs to be replaced? ive ruled out every light and gong, because those i removed a long time ago. Strange that OBC is shared in 2 diferent fuses that are shared with random lights.. Need help Please!

-Artin

[alpineE30]

Hello, my car is a 1986 325e Auto. The problem im having recently is my battery drains after about 10-12 hours of being turned off. It goes from 12.62v - 11.89v in 10 hours of sitting off. So i hook up a multimeter and i see i have a 173.3mA drain. I start pulling fuses and fuse 21 is drawing 33mA and fuse 27 is drawing 140mA both combined are the only drains on my battery, every other fuse combined = .1mA. I checked the fuse diagram and here is what i got.

21 = 7.5A - Interior Lights - radio memor - instrument panel lights
- glove box - rechargebale flashlight - clock - trunk light
- seat belt gong - ignition key warning gong - **OBC**

27 = 30A - Central locking system - door lock heating? - anti-theft -
- **OBC**

How do i tell which OBC this is? ABS, Idle Control, Motronic ECU? if it is one of these how do i test if its bad or needs to be replaced? ive ruled out every light and gong, because those i removed a long time ago. Strange that OBC is shared in 2 diferent fuses that are shared with random lights.. Need help Please!

-Artin

Obc= onboard computer its next to the radio and your car is a 6 button obc im assuming since you have an e unless someone put the 13 button one in?

[dkbmxer002]

when my stereo was wired wrong the radio got power even with the car off and keys out.. this allowed the obc to get power as well and caused a drain until i fixed it.

[arty818]

thanks for the quick replies.

alpine30 -> i have a 13 buton obc no clue if its orignal or someone put it in. If it had power going to it wouldnt it be lit up or something cuz i see no light coming from it.

dkbmxer002 -> my car came with an aftermarket alpine headunit, how did u fix ur drain? did u just rewire everything to a different fuse?

[jlevie]

my car came with an aftermarket alpine headunit

That is probably the cause of the excessive parasitic drain. The fix is to remove the head unit, restore the car's wiring to original condition, then correctly install the head unit.