So I have a brand new alternator, new battery ( 1x month old ) and I just cleaned and 2x checked the ground wire on the passenger side engine mount..nothing changes..
it ONLY ever gets to 13.8v I NEVER see 14v or above and when my lights and ac and all things tgat can drain power it drops down to 13.3v but never as low as 12v..
Also , mainly when it's cold out I 1st start it and sometimes very very randomly it will throw a cel code and the traction control light turns on also and I cannot turn back on the traction control then . The codes it throws are either cyl #3 or sometimes cyl #4 missfire detected..it's also throw a tmap code once ir twice but exhibits the same exact symptoms. I can even just shut it down , wait a few seconds and restart it and itle run perfect then soon as codes are deleted and then I can turn on n off traction control no issues or anything BUT it still has that what I believe I'd a low voltage situation..
I tried and tried and tried searching where EXACTLY the main grounds are I should check and the ONLY info that pops up pertains to the passenger side engine mount one and I'm almost positive that it's ok because if it's loose or off which happened befor the car won't even crank over..
help guys ! This is annoying me and I think is the cause for not being able to run multiple things off my obd port...

 

From where does that gauge measure system voltage?

 

obd2 port and it's 100% accurate as it reads the same on my inpa.. every time it was tuned i was told it was low voltage too.. i just put on a new e gine mou t ground wire and cleaned up the contact points but no change.

 

MiniMan
I think 13.8V means that one of the 4 diodes in the voltage regulator has failed. I have the same issue, though it has not caused me any problems. 13.8V is also the voltage that trickle/conditioner chargers provide.

 

You could measure voltage with the engine running directly at the alternator B+.

If there is more than 13.8V there, you'll know there is a problem in the system somewhere. If it is 13.8V, then it may be what MVPeters said.

 

I had the alternator tested befor I installed it and checked out ok and it was brand new , id find it highly unlikely both my old and brand new alternator have failed the same exact way and show the same exact voltages..
any tricks to test the alternator on the car running ? It's not exactly in an easy access spot exp where the plug is positioned...

 

Could the low voltage be caused by mu pulley setup ?? I have a 2% crank and a 60mm pulley on my Sprintex sc so I wonder if maybe I need either a larger or smaller alternator pulley now to compensate for that...
also after more digging , my almost EXACT symptoms were present in a few other members cars and it ended up being a faulty ecu.. I wonder if that's my case , my GPS would randomly turn on and I had to remove it and even with my car completely powered down for 15min even , I could see my side marker lights , front bumper running lights and the lights on the flares flash very dim but for 1x quick flash and it would happen like every 15minuets randomly and would do it for a few hours even have the Car has been shut down..
I mean I very well could have 2x bad alternators but i just dont see that being the case exp when i had this new one tested 1st and they both present the exact same voltage issues . One alternator does not provide any less or any more volts than the other..

 

sorry I'm dumb but what is b+ ???? I have a 3x wire alternator and then the main power wire that comes off it , which wire is that ?

 

I may not be as technically (MINI) savvy as you or many of the other NAM contributors..
However, I had some weird electrical issues going on for a couple years. Low voltage/charge/drain, lights glowing etc....
I finally solved it.- Maybe a long shot but = check the "Ground bus X175 (page ECL-19, Fig. 10 Ground Bus, (left front) - in the Bentley manual.
The 10mmm nut on mine was MIA causing the BUS not grounding/grounded.

I don't recall what year Mini you have (mine '04 R53 - prefacelift)

 

B+ is the large gauge main wire that comes off the alternator on its own lug.

The 3-wire connector would be for communication/control and power supply of the alternator. With the appropriate service information, you should be able to check those 3 wires to ensure they are sending the proper voltage signals to the alternator so it functions correctly. I think any voltage checks of the alternator would have to made from below since the alternator is buried underneath the supercharger.

With your lights being dimly lit while the car is shut down and brightening every so often, seems like a control module problem. It would be interesting have a wiring diagram to see if you can trace all those lights to what they might have in common.

 

I couldn't open anything , are you referring to the nut holding the power wire on the alternator? I know forsure that is on as I 2x checked tge new nut vs old one and 2x checked I didn't tighten it too much too and break or bend that post its bolted to. I will have to try and hook a multimeter up soon as I get my car back into service mode.. I will soon enough as all that's left to do is buff my car as we fully wetsanded it now.
I still gotta track down a white pre-facelift shifter bushing also. Another member sent me one but unfortunately it was not the correct one as it musta been a facelift version..

 

Ground bus X175
Located left (driver side) just underneath the hood latch cable. Circled in red : is a thin, black, ceramic(?) "plate" or"ballast" with wires embedded in it leading to/from the wire harness.
There is a bolt and nut securing it in place... the nut was missing.

In the picture above; I replaced the missing nut.
On some models (early?) there may be two Ground bus' on either side L/R under the hood release latch cables.
Not sure if this maybe the source of you issue. Just throwing it out there. It might be worth checking.

The thread I had posted here:Confusing Voltage Drain

 

thx you ..I will 2x check that because I actually had to put back in my hoodlatch sensor that popped out..

 

mine were different but still kinda similar but I checked the bolts anyways with no luck.

 

Does anybody know if my pulley setup could be causing the kinda low voltage??? I am running a sprintex sc with a 60mm pulley and a 2% crank... I'm wondering if my voltage is normal , well normal for my pulley setup and stuff..
ooooooooor is there a way of check the ecu to make sure that its ok ? I kinda have a sneaking suspicion it may be my ecu..

 

I'm pretty sure your voltage is normal - there's little about these cars follow conventional wisdom.
Case in point, I bought my R53 new - 19 years ago. Charging voltage has always been ~13.5V. I've only replaced the battery twice, the last time being 2015 and it's still going strong.

 

I think your correct..what do you think about my video ?

 

Sooooo I'm thinking my voltage is normal and I thiiiiiiiiiiiink my bumper lights and sidemarkers are randomly lit and or will flash IS BECAUSE MY HOOD IS OPEN !
can anyone verify if a prefacelift has a setting that illuminates those lights while the hood is open as like a safety feature or something. It's the ooooooonly thing I cam think of.
I was told my markers stay lit fir 5min dimly on side as like some kinda parking lights thing in the coding but idk if that's correct or not but sounds legtit.

 

I still think it's a faulty alternator, despite MrBean's comment. I have always had a voltmeter plugged in to the cigarette lighter - it always used to show 14.2V or thereabouts, then 13.6V after the alternator change. I'll admit it has not caused any problems although the car is always in a warm garage, even in cold New England winters. I just don't think it's 'normal' - every other car I've ever owned charged at 14.2V+/-.
The lights flashing is a different issue in my opinion; if you have fitted LEDs that is the most likely cause - the cold & hot bulb checks run but can be programmed off. Residual voltage is left in the wiring, too, & causes the LEDs to glow very dimly for a few minutes. 'Error-free' LEDs or resistors will fix this.
There is a feature on some cars that can leave the left or right side parking lights on, required in some European cities for on-street parking. I think it's activated by selecting left or right before you turn the main light switch off. The lights would be at full brightness, so I doubt if that's the issue.
The pulleys shouldn't be an issue, although very high rpm may cause over-speeding.
The 14V at the battery has me mystified! I'll check mine!
While it's in service mode, I'd see if you could borrow another alternator to try out.

 

I put in a brand new , tested alternator already... when i hook a voltmeter up to my battery while running and charging I do see 14v finally...
and I think your correct with the led bulb and euro light option , I believe adriancl seen that option on in my car and we couldn't change them because my inpa cable didn't have the 2x pins jumped in order to enable coding of those driver options.
maybe once I install my new headlights AND the new front bumper lights that both come with the inline resistors and stuff so hopefully those help the residual glowing leds from the voltage check..