10 replies to this topic

[mrducati]

Lately my mini has needed regularely recharging of the battery. Now however it has gone from bad to worse. I was going to reconnect the battery, but the sparks was flying, and smoke appearing. So, i pulled one fuse at the time to find the fault, but none helped. I then removed all fuses, but the same result. So the fault must be in some "unfused" part of the electric system. What can it be? Starter motor? Alternator? ECU? How can I find out?
Car is stock 1998 Cooper.
Any help will be appreciated!

[L400RAS]

Right, the main positive battery cable runs from the battery box, underneath the car, to the starter motor at the front. The cable runs round the front subframe, and can easily be crushed when jacking up the car on the subframe. This crushing will cut through the insulation, and the bare positive will then be touching the subframe, thus a BIG short.

If you disconnect the main connection at the starter end to disconnect and eliminate all other electrics, and test continuity between the positive and earth battery cables at the boot end - if you still have continuity, you have a short in the main cable underneath the car as detailed above. The cable is quite expensive to buy, however you could just get a run of cable the correct gauge, and put some battery connectors on it.

Ryan

[mrducati]

Now I tried disconnecting the starter motor and that stopped the sparks from flying, so not the main cable.
I did forget there was fuses under the bonnet too. Now it turned out to be the fuse on the right side of the car (nearest to the right wing) in that box with four fuses that makes the sparks fly. The owners manual is in german, but does not appear to say what the different fuses are for. Can someone tell?

[chrisking2021]

Now I tried disconnecting the starter motor and that stopped the sparks from flying, so not the main cable.
I did forget there was fuses under the bonnet too. Now it turned out to be the fuse on the right side of the car (nearest to the right wing) in that box with four fuses that makes the sparks fly. The owners manual is in german, but does not appear to say what the different fuses are for. Can someone tell?

if you pull the fuse does the horn work if it does i would check the black box on top of the brake servo it has two plugs going to it if the horn does not work pull fuses A1, B1, B9, C4, B6 until you find what is causing the problem pm me if you need anything else

chris

[mrducati]

Bummer! Quite emberassed I realized I had put the battery in backwards!!! I excuse myself that I did it in the dark, and the fastening-bracket for the battery is obscuring the + and - markings, but still the same, quite embarrased... After mounting the battery correctly, there is still electicity going thru the fuse for the coolingfan, the alarm and... oh, one more (at work now, don't have the car here to check). Don't dare mounting the fuses in fear of a new short... Am I correct in not doing this? Is there a way of telling if everything is as it is supposed to? What have I damaged when I mounted the battery backwards?
The car turned the starter motor alright, but expectedly it did not start.

[L400RAS]

...What have I damaged when I mounted the battery backwards?
The car turned the starter motor alright, but expectedly it did not start.

Hi mrducati,
You may have frazzled the alternator with the battery on the wrong polarity Not the worst, alternators are quite cheap. This may be the cause of not starting, but dont know.
Do you have any aftermarket ignition / Britpart magnetic points kits fitted? - if so these may be dead, and thus no spark at the plugs.

[mrducati]

You may have frazzled the alternator with the battery on the wrong polarity Not the worst, alternators are quite cheap. This may be the cause of not starting, but dont know.
Do you have any aftermarket ignition / Britpart magnetic points kits fitted? - if so these may be dead, and thus no spark at the plugs.

Thanks for reply again L400RAS! No, it's standard ignition, so I hope that is alright. Is here any way of checking if the alternator is alright other tan buying a new one, and see if matters improve?

[Puddings]

with the car started check voltage at the battery (right way round of corse) and you should get 14V DC or there about if not the alternator is faulty

[mrducati]

with the car started check voltage at the battery (right way round of corse) and you should get 14V DC or there about if not the alternator is faulty

Thank you everybody! It took me some work just to get the car started, but now I've found out there is no increase in voltage whith the engine running (around 12,5V), so the alternator is busted I guess. Also I think there is a short in the cooling fan (there is electricity going thru the fuse ignition on or off), so I'll change both, plus the battery so the car will be ready for the winter.

[mrducati]

Argh!
I bought and fitted a new alternator, but the battery-warning-light is still on, and the multimeter shows no increase in voltage when I start the engine (12,5, V engine running or not). What else can it be?

By the way, the alternator belt is really hard to tighten (because of little space, and that square bolt-head is protruding so little from its hole! Does anyone have any good tips?

[icklemini]

Hi mrducati,
You may have frazzled the alternator with the battery on the wrong polarity Not the worst, alternators are quite cheap. This may be the cause of not starting, but dont know.

MPI alternators are uber expensive compared to normal mini alternators :s

Do you have any aftermarket ignition / Britpart magnetic points kits fitted? - if so these may be dead, and thus no spark at the plugs.

Things like that havent got a home on a 1998 MPI Cooper...

I bought and fitted a new alternator, but the battery-warning-light is still on, and the multimeter shows no increase in voltage when I start the engine (12,5, V engine running or not). What else can it be?

There are a number of 'fusable links' in the wiring down near the starter...
These arent normal fuses.. basically it looks like a normal cable/wire except that the fuse is built into it...
Trace through and check the continuity of the wires that go to the alternator....