Hello everyone!

I have a 2005 skoda fabia 1,4.

I have a problem, i drove like normal and then first the parking break light comes on, then abs, airbag and then the rest of the lights and then the engine dies. seemed like a power issue, i´ve swapped battery, checked the alternator which works fine (gives the battery 1v extra when engine runs).

The problem is that when it dies i cannot start it, seems like a flat battery when i try and then i left it for a couple of days and then it started and drove like normal, until same thing happened again and now it´s dead.

Ive had a problem with the power steering that it sometimes just disappears and when i restart the engine it works again (writing this just in case someone know a correlating problem with this).

 

Does anyone know what´s wrong with my car?

Yes, your charging system output is hopeless, 1V more than battery is no good, you need 14.4V while the engine is running and 12.7V from the battery when it's not running.

Thank you!

Could it be anything other then the alternator or is it just to swap it?

Measure the voltage right at the alternator to check.  Positive meter probe carefully on output cable crimp terminal if you can get to it without risk of shorting your probe to other things, negative probe on a scraped clean bit of alternator's metal casing. If the voltage here is nearer 14.4/14.5 (with cold engine, idling), then the alternator is probably not at fault.

 

Tarnishing/corrosion of the connections of the main positive and earth cables are the things to look for if the alternator is blameless.

Unbolting, cleaning and reconnecting each end of each cable may fix this. Battery negative terminal off before anything else, for safety.

Edited 4 August, 20214 yr by Wino

Diesel or petrol 1.4? If petrol, MPI or 16 valve?

 

9 minutes ago, Wino said:

Diesel or petrol 1.4? If petrol, MPI or 16 valve?

 

 

If it's a 1.4 petrol it won't be an MPI as they only went up to 2003.

Thank you all for putting your time in helping me. It's petrol. Im going to the car tomorrow to try to fix it. Will need to jump start it first but hopefully it keeps running so i can troubleshoot it. Feels like it should be connectors as it comes and goes.

Ideally you'd charge the battery fully before trying to fault-find the alternator and its cabling. Is there a better battery you could borrow and put in temporarily?

An intermittent short circuit inside the battery can give the symptoms you mentioned if you find the system voltage is jumping from above 12v to 10.5v and back above 12v again.

1 hour ago, Wino said:

Ideally you'd charge the battery fully before trying to fault-find the alternator and its cabling. Is there a better battery you could borrow and put in temporarily?

Since i swapped it and it's probably nothing wrong with the old one i can charge it before trying

51 minutes ago, BigEjit said:

An intermittent short circuit inside the battery can give the symptoms you mentioned if you find the system voltage is jumping from above 12v to 10.5v and back above 12v again.

i thought so too at first but now the battery is swapped and i have the same fault.

Check your earthing points. There's one on the wing near the battery.

Have a look on the forum for two wiring faults. The starter motor "signal" wire. And alternator sense wire(s).

 

J.

 Found this connector for the battery plus, when i measured the V between these spots it was like 0,2-0,3V difference so i took it off and cleaned the connectors, now it´s the same between and now the V is a little better on the battery when engine is running. From 12,7 (off) to 14,13 on idle when i turn off all the electricity but then i tried to turn everything off to see what happens under load. When everything is on (ac, radio, blinkers, headlights etc) the V jumps from 14,13 to 12,78. Is this normal or is the output too low? If so, can it be anything else then alternator?

On 04/08/2021 at 20:48, Wino said:

Ideally you'd charge the battery fully before trying to fault-find the alternator and its cabling. Is there a better battery you could borrow and put in temporarily?

 

Bad resolution on last pic

That's a fuse. Good to have clean connections to it, but I'd actually expect the earth connections from alternator to battery negative to have more losses.

 

With everything connected and some current consumers switched on, measure voltage between battery negative post and alternator case metal (scratch through any corrosion to clean metal). This will give a direct reading of losses in the earth path.

Sounds like you're losing far too much voltage between alt and battery.

This is the reading i got from this minus on battery negative pole.

headlights on, ac on, radio, blinkers.

 

is this alot?

No, that's not bad actually.

If you can reach the positive output connection on the back end of the alternator without danger of shorting the probe to other things, try measuring volts between there and battery positive with the same loads on. That will measure total loss in the positive wiring.

 

Took of the cap on the nut and measured from this one to battery positive pole and i got  - .327VDC with the same load

Looks lite this when i measure those points

I also tried measuring V on alternator outer casing and the same nut (positive output) and it's at 13,3V there and sometimes it jumps down tp 12,5v. Isnt this very low right at the alternator?

Yes, but see if that improves if you raise the engine rpm (assistant probably required).  If the battery is taking a very high charging current, it may be more than the alternator is capable of generating at idle rpm.

 

This is one reason it's good to do the testing with a known good battery in place.

Edited 8 August, 20214 yr by Wino

12 minutes ago, Valleth said:

Took of the cap on the nut and measured from this one to battery positive pole and i got  - .327VDC with the same load

 

If the alternator does manage a 'good' voltage (when measured at the alternator) at higher rpm, changing this positive cable out may well be helpful.  Do check that the positive battery clamp isn't loose (or dirty) on the battery post first though. Also the connection onto the underside of the fuse tray, though that is well protected from the weather and has probably never been undone.

6 minutes ago, Wino said:

 

If the alternator does manage a 'good' voltage (when measured at the alternator) at higher rpm, changing this positive cable out may well be helpful.  Do check that the positive battery clamp isn't loose (or dirty) on the battery post first though. Also the connection onto the underside of the fuse tray, though that is well protected from the weather and has probably never been undone.

at 2500 rpm's i got 14,4 at the alternator (the nut and outer casing) meanwhile i got 13,9V at the battery between the poles. Does this mean bad positive cable from alternator to battery?

Great work.  I think that means the alternator is probably not at fault.

Yes, I think your conclusion is correct, provided that there is no loose or dirty connection between battery positive post and the fuse.

The alternator positive cable may be bundled in with some other cabling, but you could just replace the high current thick cable, disconnecting both ends of the old one, leaving everything else in place, rather than replace the whole alternator loom.

 

I'll check the minimum mm² size requirement of that cable for your car, one moment.

 

1 minute ago, Wino said:

Great work.  I think that means the alternator is probably not at fault.

Yes, I think your conclusion is correct, provided that there is no loose or dirty connection between battery positive post and the fuse.

 

Cant explain how grateful i am for your help. Im going to take it off now and see if i can find any visible damages.