[Mk2] [Turbo] dash warning lights-battery, alternator and unknown

[Flip1977]

Oh great! Maybe fixing the regulator might be the best plan then!! It doesn't sound (nor look) like the alternator just "pops out" either, perhaps requiring the removal of my exhaust (with exceedingly corroded cat connections) as well? I can see this not going well.

[toxo]

What type of MR2 do you have? There are a few different ways of getting it out...

[Flip1977]

UK car, R reg, T bar with power steering but no air conditioning.

Hopefully you're going to say this is the easiest of all of them, and after undo-ing two bolts it just falls out of the car?

[toxo]

Easier on an NA than a turbo as the alternator is smaller. Undo a few bolts (above and below) and 2 electrical connectors and then you can pass it along to the gearbox side of the car and lift it over the 'box and out.

[Flip1977]

Ah clever, yes I can see that has potential, thank you! Now all I need is a new alternator that works then!

[Flip1977]

So, I will sort the alternator as soon as possible, as that seems to be the problem - but I have an additional discovery too, the battery will go flat after a day or two of it not being used... I assumed this was just a crap battery, but I fitted a new high power one on Wednesday evening, and used the car Thursday and Friday, then tried to start it today but it was completely dead.

So would the draining problem be fixed by an alternator change too?

[Peter Gidden]

So would the draining problem be fixed by an alternator change too?

Depends what the fault is.

IF the alternator is good, i.e. charging AND the battery is good, then something is discharging the basttery at night.

IF the alternator is bad AND the battery is good, then there is no charge going into the battery and it will go flat from just driving the car.

[Flip1977]

Well, the battery is good and healthy, that is the only known quantity at the moment. It is a new battery purchased and fitted less than a week ago, when the original battery flattening started. A new battery was the obvious and easiest remedy, but it seems not the correct one!

The alternator, or more correctly, the voltage regulator is faulty - which means there is too much voltage being supplied, which I am balancing out by having the lights on or rear demister on as required. Please note, the alternator is still charging the system quite happily, just a little keenly at times. However, when the car is left locked and alarmed for 1.5 days without being driven or even touched, the battery was drained so much that the alarm key fob no longer works, nor does the central locking.

I'm hoping that this can give a clue as to any potential further problems, or if replacing the alternator might fix this problem too? I appreciate that a faulty alternator should only affect the car when its running, but I'm wondering if a malfunctioning voltage regulator in the alternator might be causing the drain somehow?

[Peter Gidden]

The alternator, or more correctly, the voltage regulator is faulty - which means there is too much voltage being supplied

Then replace the alternator.

Pointless tryning to diagnose an electricsl fault when you know one of the fundamental component parts in the electrical system is not working correctly.

[Flip1977]

I was just trying to ascertain if anyone else had seen similar symptoms of a faulty alternator discharging the battery when the engine wasn't running - perhaps saving me replacing unnecessary components. Alternator is on order anyway, I'll get this fitted Wednesday and go from there.

[shogun666]

hi did you solve this problem as i have the same thing

[Peter Gidden]

hi did you solve this problem as i have the same thing

And what tests have you done?

[Flip1977]

Hi there,

I replaced the alternator, and all was well. Changing the alternator was a bit of a pain though! For reference, it seems that the faulty voltage regulator in my alternator was discharging the (perfectly good condition) battery overnight when the car was off and locked.

[HighwayStar]

That did seem the most obvious suspect.
That said dying starter motors can drain batteries and kill alternators too in my experience. If problems had persisted that would be the next thing to check. Glad you got it sorted fella and well done to those who came to your aid.

R

[madbasshunter]

My old escorts alternator started discharging the battery when parked, the red light used to glow on the dash when you turned the ignition off.