Hi all,

 

A quick question re: diagnostics of Alternator for the early Skoda Fabia model (2000 I believe), it's a 1.4 comfort.

 

Nutshell: Battery at 12.56V, jumping to 13.5V+ when engine turned on, then slowly dropping down well below 12.56V even with engine revved at a constant 2000RPM. Does this mean the alternator is busted?

 

Backstory:

Essentially the battery died on me the other day, totally dead, nothing. Not even juice to wind up the electric window until I left it for half an hour.

Multimeter reading on the battery was at: 11.62V, so well and truly kaput.

 

Charged the battery, not for long enough, but wanted to test it (I'm impatient like that), took the car for a short drive hoping it would charge as I went, and the power died whilst idling.

Was a real slog getting it to a suitable spot for looking at, with the power steeing dead!!

 

Replaced the battery with a brand new one - however the red battery light flashed on with a loud beep at least twice on the ride home (about 10-15 minutes).

 

Since I got back I tightened the connectors and tested the battery: 12.56V with the engine off. With engine on it spiked to about 13.5V+, then slowly dropped going down below 12V, even with the car revved up to a steady 2000RPM.

I suspect, but want to confirm: is this because the alternator is broken?

If so I reckon I will have to try to fix it myself - far too skint to afford otherwise. A rough idea of the cost of paying a garage to fix the alternator would be great if possible

 

Thanks for your time everyone, any help much appreciated.

It's not the wiring fault that's common with these is it?

 

About a year ago I was losing power in my Fabia, lights shutting down, wipers not working etc. It seemed the alternator wasn't charging the battery. Replaced the alternator but problem persisted. It turned out there was a damaged cable (load signal wire I think) that told the alternator to charge the battery or something?

 

Is your battery warning light working? 

 

http://www.briskoda.net/forums/topic/248615-no-battery-warning-light-alternator-not-charging-unless-revved/

 

http://www.seatcupra.net/forums/showthread.php?t=209472

If your battery light does not come on with the ignition then the load sensor wire is broken, otherwise your alternator is goosed but you can buy a new brush pack off ebay for about £15 and change it yourself, this should fix it.

Voltage with the engine running should be 14.4V.

Take voltage regulator/brushpack off the rear of the alternator and measure brush length.  5mm minimum according to Haynes. I suspect you'll find yours are shorter.

 

If the battery light doesn't come on with ignition and go out again with engine running, check the blue wire going to the alternator, from the 'onboard supply control unit' in the cabin.

Hi guys, thanks for the rapid responses

Battery light comes on with ignition on, then when engine starts it goes off - which I believe implicates the alternator still...?

 

I'll have to look into how to dismantle alternator/get at the brush pack. No experience working with cars - just a skint recent father of one looking to save some cash!

 

As an addition: engine seems to be bit shakier than usual at low revs/idling, not sure if that is related.

 

Thanks once again everyone!

 

Phil

Hi guys, thanks for the rapid responses

Battery light comes on with ignition on, then when engine starts it goes off - which I believe implicates the alternator still...?

 

I'll have to look into how to dismantle alternator/get at the brush pack. No experience working with cars - just a skint recent father of one looking to save some cash!

 

As an addition: engine seems to be bit shakier than usual at low revs/idling, not sure if that is related.

 

Thanks once again everyone!

 

Phil

Behaviour of the battery light is normal, indicating that the exciter wire (the blue one) is intact, and so is doing its best to kick the alternator into life at start-up.

There's probably a black plastic cover over the back of the alt, which is held on by a couple of screws.  You'll have to disconnect the main output wire and unplug the two-pin signal connector before you can remove this cover and get at the volt reg.  Not sure whether there's enough access with the alternator in-situ.  Disconnect battery negative before detaching the thick wire from the alt though, you don't want that wire shorting to ground or you'll blow a (big) fuse.

If your battery light does not come on with the ignition then the load sensor wire is broken, otherwise your alternator is goosed but you can buy a new brush pack off ebay for about £15 and change it yourself, this should fix it.

Voltage with the engine running should be 14.4V.

 

Should I be concerned if my readings are about 13.5-13.8V and below 13V with all possible things turned on (a/c, full beam, fog lights, blower on highest speed etc)? I've never seen the multimeter say 14 or above no matter what.

Edited 10 March, 201511 yr by Alexandru

Should I be concerned if my readings are about 13.5-13.8V and below 13V with all possible things turned on (a/c, full beam, fog lights, blower on highest speed etc)? I've never seen the multimeter say 14 or above no matter what.

 

Maybe your old-tech MPI has an old-tech alternator, I don't know, I was assuming the OP had a 16V Comfort like mine.

Ive just tested my battery after suspecting some charging issues. (1.9 tdi 2002 Fabia comfort)

 

14.3 something.. with no load and 3000 revs, 

14.1 with main beam and rear window heater on.

 

battery light not on when initial key in ignition.

 

I've put the battery going flat down to me driving regular round the doors, 5-25 min journeys at really low revs.

 

Can't see any visible signs of wires loose or corroded from alternator end (looked from top only).

 

Does this mean its still worth checking the continuity.. I only came across this little issue whilst trying to identify why ABS light was on.

 

 

...Does this mean its still worth checking the continuity..

Yes. If the battery light in the cluster doesn't come on with ignition switched on, and go out when engine is started, the blue alternator exciter wire is broken somewhere. Your alternator is not working properly if this wire is broken.  Just to clarify, you won't see any dash lights when just the "key is in ignition", you need to turn it until all the warning lights self-test, then you should see the battery light as one of them.

 

You need to look from underneath the car to find these wire breaks.

Yes. If the battery light in the cluster doesn't come on with ignition switched on, and go out when engine is started, the blue alternator exciter wire is broken somewhere. Your alternator is not working properly if this wire is broken.  Just to clarify, you won't see any dash lights when just the "key is in ignition", you need to turn it until all the warning lights self-test, then you should see the battery light as one of them.

 

You need to look from underneath the car to find these wire breaks.

 nice one.. 

looks like its a wriggle underneath while its still dry!

 

I'll see if I can get some pix and report back, seems other folk have had this excitement!

  :p  Cheers Wino

When the load signsl wire on mine broke I had intermittent ABS light on too. It broke somewhere underneath the battery I think, a common fault.

Battery light on for split second

Edited 12 March, 201511 yr by Tony1234

Yup two broken wires on bottom don't know if I can get a pic on here

:-)

On your way to problem solved.

very common problem....
http://www.seatcupra.net/forums/showthread.php?t=209472
And so easy to fix it.

Section: Engine
Error code: 18265 - P1857 - 000
Description: Load Signal: Error Message from ECU

Section: ABS
Error code: 17911 - P1503 - 35-10
Description: Load Signal from Alternator Term. DF: Implausible Signal

Edited 13 March, 201511 yr by FinnVrs