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Discussion Starter #1
I have a problem with my 55 plate Mini Cooper S. something is draining my battery done a parasitic battery drain test and got a drain of 0.51A (510mA) checked fuses and the results were -

F4 5A BC1 (X254 27) Constant power (80mA)

F15 20A Sunroof module control unit (30mA)

F21 10A Control module for instrument cluster (240mA)

F24 5A Electronic immobilizer control unit/Horn for antitheft alarm system EWS (60mA)

I’m still missing 0.9A (90mA) which I cannot locate a drain for.


These were in the passenger footwell
The fuses under the bonnet were ok.

I’m good with cars but confused as to what might be my next steps?

Any help appreciated
 

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5,386 Posts
I have a problem with my 55 plate Mini Cooper S. something is draining my battery done a parasitic battery drain test and got a drain of 0.51A (510mA) checked fuses and the results were -

F4 5A BC1 (X254 27) Constant power (80mA)

F15 20A Sunroof module control unit (30mA)

F21 10A Control module for instrument cluster (240mA)

F24 5A Electronic immobilizer control unit/Horn for antitheft alarm system EWS (60mA)

I’m still missing 0.9A (90mA) which I cannot locate a drain for.


These were in the passenger footwell
The fuses under the bonnet were ok.

I’m good with cars but confused as to what might be my next steps?

Any help appreciated
when you checked these readings did you lock the car for 3 minutes then take the reading, as the body control module should go to sleep around 3 minutes after car is locked, i know its a pain hence why garages charge a lot of labour time for electronics as every time you open car to move tester you need to wait 3 minutes again, also you cant leave these cars unlocked overnight etc as the body control module will keep come alive again. if you did and these readings are what you have i would suspect body control module faulty or sunroof module maybe.. i have a number of testers and cables that i can probe read a few fuse draws at same time while stood outside the car when its locked, 250ma is fairly normal draw on some cars where on other 100ma is the norm, have seen warn out batteries die over night from a normal load when really worn out, i had a chrysler jeep that would randomly do what yours is doing, i bought it off a guy spares and repairs because he had tried everything so he said,, turned out was the main wiring lomb it dips down and collects water inside and then add road salts from winters this caused a environment like a massive resistor and was like a heater element left on,,, so wiring that wet needs to be checked and pulled apart, also every relay needs checking as a stuck on relay very common when they get heat damaged will draw amps.. the body control modules bless it hmmm what a stupid design on all cars they mount circuit mounted relays on circuit board in side very hare r=to repair and expensive to replace these fail for a past time, and are a royal main in arse to diagnose even when you know what you are doing as are some faults on cars,, just had a citroen this week that has tormented me and everyone else who has worked on it,, but think have found it now, faulty brand new thermostat housing dragging the ecu down, or the ecu the software inside it has been damaged for a positive short circuit to live ie the first problem,, electrical problems are the hardest to deal with without th correct info as well
 

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Discussion Starter #3
I have a problem with my 55 plate Mini Cooper S. something is draining my battery done a parasitic battery drain test and got a drain of 0.51A (510mA) checked fuses and the results were -

F4 5A BC1 (X254 27) Constant power (80mA)

F15 20A Sunroof module control unit (30mA)

F21 10A Control module for instrument cluster (240mA)

F24 5A Electronic immobilizer control unit/Horn for antitheft alarm system EWS (60mA)

I’m still missing 0.9A (90mA) which I cannot locate a drain for.


These were in the passenger footwell
The fuses under the bonnet were ok.

I’m good with cars but confused as to what might be my next steps?

Any help appreciated
when you checked these readings did you lock the car for 3 minutes then take the reading, as the body control module should go to sleep around 3 minutes after car is locked, i know its a pain hence why garages charge a lot of labour time for electronics as every time you open car to move tester you need to wait 3 minutes again, also you cant leave these cars unlocked overnight etc as the body control module will keep come alive again. if you did and these readings are what you have i would suspect body control module faulty or sunroof module maybe.. i have a number of testers and cables that i can probe read a few fuse draws at same time while stood outside the car when its locked, 250ma is fairly normal draw on some cars where on other 100ma is the norm, have seen warn out batteries die over night from a normal load when really worn out, i had a chrysler jeep that would randomly do what yours is doing, i bought it off a guy spares and repairs because he had tried everything so he said,, turned out was the main wiring lomb it dips down and collects water inside and then add road salts from winters this caused a environment like a massive resistor and was like a heater element left on,,, so wiring that wet needs to be checked and pulled apart, also every relay needs checking as a stuck on relay very common when they get heat damaged will draw amps.. the body control modules bless it hmmm what a stupid design on all cars they mount circuit mounted relays on circuit board in side very hare r=to repair and expensive to replace these fail for a past time, and are a royal main in arse to diagnose even when you know what you are doing as are some faults on cars,, just had a citroen this week that has tormented me and everyone else who has worked on it,, but think have found it now, faulty brand new thermostat housing dragging the ecu down, or the ecu the software inside it has been damaged for a positive short circuit to live ie the first problem,, electrical problems are the hardest to deal with without th correct info as well
Thanks for the reply. At first I thought it was the battery so got a new battery for it to die a few weeks later with daily use. I have done these tests with the doors closed ect after 20 minutes. I will look at what you’ve mentioned
 
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