Mystery electrical fault MK1 SDi Fabia

[stevekd]

I have had this Skoda Fabia SDi 2003 for a year, it drove all over France and into Italy this year, without a fault. On coming back to the UK it went straight through the MOT then had a service. Got up one morning and the car was as flat as a pancake.

Battery is good. Jumped the car, went on a run, all seemed fine for about 15 miles then the power steering light came on the dash, lost power steering, no indicators, no windows, no speedo. Got home and noticed the brake lights were stuck on, even after ignition off. 

Car went flat over night.

Took it to a local garage, changed the switch for the brake light, fine, took the car for a run, same thing happened with the steering ect.

Brake lights do not stay on any longer.

Took the stero out, car still went flat, jumped it, took it to the garage.

Two days later, the garage calls and says they give up, they can't work out what is happening.

A bit of further info, when the steering light comes on the steering goes, the indicators go, rev counter goes temp gage goes ect and all lights on the dash go out, if you disengage the clutch the dash lights up, indicators work, rev counter ect work but the steering doesn't come back, when this all starts to happen, you rev to over 2000 and all the stuff goes off again !!

What on earth ? Any ideas?

Garage said an error code of intermittent charge but says the alternator is good !!

Edited 5 January, 2016 by stevekd

[Breezy_Pete]

Does the battery light come on when you switch on the ignition, and go off again once the engine is started?

[stevekd]

Thank you for your interest. the lights go on and off as normal, until its been driven for around 40 mins, then all hell breaks loose. 

Does the battery light come on when you switch on the ignition, and go off again once the engine is started?

[Breezy_Pete]

Usually, that sort of 'alternator doesn't give output at low revs' symptom means the blue exciter wire to the alternator is broken. That results, in turn, in the battery light in the cluster not ever lighting up.

[KenONeill]

I wonder, could a battery, alternator or major earth connection be breaking down when hot? I have no idea whatsoever how to test for this, but it fits the symptoms.

[garethw]

Sorry to hear of your problems. Unfortunately the cars are now old enough to start experiencing these types of electrical hicups.

 

The symptoms you are reporting are typical of the battery voltage falling to a critically low level and as suggested by everyone else the most common cause of this is the wire from the ECU to the alternator being intermittant or completely broken.

 

From your initial description is part of the problem that the battery gets discharged when the car is left overnight ?

 

If this is still the case it may help to determine what is actually causing this. Do you have access to any of the following a multimeter/VCDS interface/battery charger ?

 

Other that the normal boot or courtesy light left on problems or radio problems it is possible for the alternator to have an internal fault that would cause a low current drain on the batterry and possibly reduce the charging current when hot, however this is hard to diagnose.

 

Another thing that I would watch for is that pattern part brake light switches are pretty hopeless, I fitted one and it lasted exactly 8 miles before it failed, so check for a re-occurance of your initial fault although I would expect the glow plug warning light to be flashing if that was the case.

[poiuytre111]

What made it crystal clear for me in a similar situation was to leave a voltmeter semi-permanently connected so I knew when it was and when it wasn't charging. I picked up a cheap dash-mounted temp and voltage guage on ebay. In my case I could see that it wasn't always charging and it was the infamous wire - Wino usually provides links to some excellent pictures. By the way, mine did the normal thing with the alternator light but it was lying.

[stevekd]

Sorry to hear of your problems. Unfortunately the cars are now old enough to start experiencing these types of electrical hicups.

 

The symptoms you are reporting are typical of the battery voltage falling to a critically low level and as suggested by everyone else the most common cause of this is the wire from the ECU to the alternator being intermittant or completely broken.

 

From your initial description is part of the problem that the battery gets discharged when the car is left overnight ?

 

It does indeed go totally flat over night, even the clock is dead, what is strange is initially the break lights were on all the time, I was hoping a replacement switch would solve the problem and it did, but battery still drained. 

 

If this is still the case it may help to determine what is actually causing this. Do you have access to any of the following a multimeter/VCDS interface/battery charger ?

I do have a digital multimeter and can buy a battery charger  

 

Other that the normal boot or courtesy light left on problems or radio problems it is possible for the alternator to have an internal fault that would cause a low current drain on the batterry and possibly reduce the charging current when hot, however this is hard to diagnose.

 

Another thing that I would watch for is that pattern part brake light switches are pretty hopeless, I fitted one and it lasted exactly 8 miles before it failed, so check for a re-occurance of your initial fault although I would expect the glow plug warning light to be flashing if that was the case.

 

the glow plug light did flash before replacement of the switch

 

one point to mention apart from thanking for the help is, i did measure the battery terminals reading 7.5 volts when running, but the alternator was tested by a local garage and passed. i get the car back in the morning., oh another point, the garage had it two nights and the battery only went flat on one night?

[stevekd]

What made it crystal clear for me in a similar situation was to leave a voltmeter semi-permanently connected so I knew when it was and when it wasn't charging. I picked up a cheap dash-mounted temp and voltage guage on ebay. In my case I could see that it wasn't always charging and it was the infamous wire - Wino usually provides links to some excellent pictures. By the way, mine did the normal thing with the alternator light but it was lying.

Thanks for the reply.

The wire, has anyone got a pic?,