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Discussion Starter · #1 ·
2005 Mini Cooper 1.6 r50
So I’ve been diagnosing my gf mini for 2 weeks to no success, I changed her disks/pads 2 weeks ago and the car rolled off the jack, the jack went up between the fuel tank and the chassis on the rear left of the car, I beleive it caught the plug for the abs sensor, since then her speedo has been turning on and off very dramatically and all the warning lights blink on and off, sometimes it settles to a frozen speed and just has the abs and tyre flat lights on, upon scanning the abs unit with an obd reader I got an 5df7 code which states that the abs-dsc system sees >18V, upon seeing this I checked her battery voltage which was sitting at 13v with the car turned off, I also noticed the battery is leaking(only a week old brand new battery) when the car is running at idle it sits at 12.5V and when we rev the car afew times and get the speedo to go haywire again the voltage spikes over 19v to the battery, I tried unplugging the abs plug I beleive to have caught and the car runs fine under 3k revs no possesed spedo, I forgot the mention the abs plug and wiring looked fine, if anyone knows how to diagnose a short inside the abs wiring I’d be appreciative, now with the plug unplugged it only sees the short above 3-4k revs, have I blown the regulator in the alternator with a damaged abs plug? Or have I possibly damaged the wiring from the abs plug to the front of the car and this is still shorting even thou the actual abs sensor is unplugged, I don’t know how it lasted 2 weeks periodically charging the battery at 19v and didn’t blow up the battery 😂 any help appreciated
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alternator regulator faulty from sound of that ,, when it over charges it causes all kinds of over voltage problems , change alternator,, if keep using 19v will fry the battery ie will boil the acid and distort the plates in it, worst case is battery will explode if gases ignite
 

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As Mike says do not run the car if its generating 18+ volts at the battery, you could easily damage any of the electronic modules.

It does sound like the alternator but if you still suspect damaged cables check the battery voltage sense wire connection that runs from the battery to the alternator. If this is broken it will allow the alternator to generate max voltage output.
 

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Discussion Starter · #4 ·
alternator regulator faulty from sound of that ,, when it over charges it causes all kinds of over voltage problems , change alternator,, if keep using 19v will fry the battery ie will boil the acid and distort the plates in it, worst case is battery will explode if gases ignite
Is there any way I can diagnose a faulty regulator before I take it out ya know urself there’s abit of work involved in replacing as this alternator is only in the car about 12 months and was bought brand new last year, if not I will take it out and drop it to my repair man i know he should be able to check the regulator
As Mike says do not run the car if its generating 18+ volts at the battery, you could easily damage any of the electronic modules.

It does sound like the alternator but if you still suspect damaged cables check the battery voltage sense wire connection that runs from the battery to the alternator. If this is broken it will allow the alternator to generate max voltage output.
yea car is parked up now until this is fixed, I would swap the alternator but I’m afraid there’s a damaged cable causing the regulator to blow in the alternator? It’s less than a year old like, il look for a battery sensing wire between the alternator and battery now and I assume I check for continuity between the two, I’m obsessing over the abs because of the fault code reading over 18V for the abs-dsc unit, that and all this started happening right after we did new brakes and pads all around, if I can’t find a short by Saturday il be taking alternator to a mechanic who rebuilds them down the road. I should mention on another obd reader we get a speed sensor fault, the vss on live data will read 0km/hr when the dash is flashing and the car is cruising down the road, I pulled up live data for all 4 wheels individually thou and when the vss reads 0 all 4 wheels are reading the real speed and accurately. So I think I can assume the abs wires arnt damaged because of this or there readings would be off? We’ve had awful rain the past month here and loads of floods, maybe Mike has it right maybe it’s just the alternator and it was caused by it getting soaked driving through floods 🤔🤔 itl be too dark to remove the alternator after work so itl be Saturday before I know anyway, thanks for the advice lads 👍
 

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Discussion Starter · #5 ·
Also just to add aswell in case it helps, power steering turns off when it spikes to 19v, and a week before all this happend the clutch pedal went to the floor, I bled the clutch slave after I did the brakes and it came back to normal thou so I assumed it’s not linked to the electrical issue, I get some weird gulping noises from around the brake pedal when I engage abs braking really hard and just before I stop the brake pedal will go soft, again I didn’t think it was linked to the electrical issues but might have been worth mentioning, brakes work fine under normal operation
 

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Discussion Starter · #6 ·
Is it possible this is an abs pump issue? I read that the brain for the abs pump can go in gen 1 minis, just when I cleared the 19v code and it settles back to 12.5v I can hear a gulping like oil moving under the steering wheel around the footwell, and that would make sense why I keep getting the abs-dsc over 18v code because maybe the abs pump is gone haywire?
 

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In your OP I understood that you had measured high voltage at the battery? If so then the ABS fault is giving correct information. Generally modules will try and disable functions when high voltage is detected to protect themselves.

One thought - have you checked the fuses (F39 in the footwell box). A long shot as I would of thought a blown alternator fuse would have stopped all charging and brought up the battery lamp.

To test the alternator would require access to it, so most of the work needed to replace it anyway.
 

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Discussion Starter · #9 ·
In your OP I understood that you had measured high voltage at the battery? If so then the ABS fault is giving correct information. Generally modules will try and disable functions when high voltage is detected to protect themselves.

One thought - have you checked the fuses (F39 in the footwell box). A long shot as I would of thought a blown alternator fuse would have stopped all charging and brought up the battery lamp.

To test the alternator would require access to it, so most of the work needed to replace it anyway.
Ok so to date I’ve removed the alternator and dropped it to a guy who rebuilds them, he said he checked the regulator and it was faulty, I’ve replaced the alternator now and the car won’t start, I get ignition light on and then nothing when I turn to start, no clicking like the battery was dead ethier I’ve got 12.6V on the battery so it’s not the problem, when I connect the battery however I get quite a large spark every time, I’m thinking I’ve got a short somewhere that needs diagnosing would you agree? No codes showing anymore and I’ve got the engine light and battery light upon ignition, I’m going to check for parasitic draw when I get home and start pulling fuses to try to diagnose which circuit could be causing the draw, other than that any advice is holy welcome, im going to start by checking any and all abs fuses as that’s where the code reader was seeing >18V when it was throwing codes,
 

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Discussion Starter · #10 ·
and I did check all the fuses a week ago but now I’ve got the battery lamp on (never on before hand) I better check that alternator fuse again maybe it blew when I connected the battery last night 🤔
 

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I'm no expert but if you have not replaced the battery since it was (likely) cooked that may still be the issue. I'd try a new / another battery.
 
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