Hi Fabia 1 forum, my son's 2003 Fabia 1.2 has developed a fault where the abs and pas warning lights are on when the engine is running. Searching on here throws up numerous things to check and it seems the alternator load sensing wire is a common fault. I have checked the wiring visually and it appears okay, also checked the 40a strip fuse which is okay.

The charge warning light illuminates as normal when ignition turned on and goes out when engine starts. The pas and abs appear to be working normally as well.

On checking the battery it is showing 12.8 volts engine off but goes up to 15.3v with engine running, which suggests to me the alternator is overcharging.

My question is could a broken load sensing wire to the alternator cause this or does it sound more like defective alternator ? Cheers ☺

15.3v running sounds like an alternator "control box" failure to me. I don't know if the control box is separate on that model or not, but it needs replacing before it cooks the battery and ECUs. The ABS is already protesting!

 

Take the car to an auto electrician to get it checked properly, and for free as long as you buy the bits there.

Yep, sounds like a voltage regulator failure to me too. On the back of the alternator, under the black plastic cover.  Not sure how readily available or costly the module might be though vs 2nd hand alternator.

If you have a look at any part numbers you can see on the alternator, I can have a look at a spare I have at home later, and if it's the same, read off any part numbers from the volt reg for you.

 

My understanding is that the load sensing wire is just that *sensing*, not controlling; so even if it's broken, the alternator will still do the same thing, it's just the ECU won't know what's going on, nor be able to pass on true info via CANbus to other modules. The ECU might default to assuming 'max load' in the absence of a signal though, so well worth checking carefully for wiring continuity if possible. It's the non-blue wire.

Thanks Wino, have got rained off at the moment...Need to get it jacked up and properly check those wires. Alternator does look very oily and possibly original, so whilst a broken wire would be cheaper a new alternator might be on the cards. Interestingly the pas light only stays on if you start the engine before letting it complete its self test and go out, if you leave it a few seconds with ignition on, and allow the light to go out it stays out. The abs light is on all the time with engine running and the abs isn't working as I've just tried it and it skids !

Edited 16 February, 201511 yr by classic

Thanks Wino, have got rained off at the moment...Need to get it jacked up and properly check those wires. Alternator does look very oily and possibly original, so whilst a broken wire would be cheaper a new alternator might be on the cards. Interestingly the pas light only stays on if you start the engine before letting it complete it's self test and go out, if you leave it a few seconds with ignition on, and allow the light to go out it stays out. The abs light is on all the time with engine running and the abs isn't working as I've just tried it and it skids !

Yeah, that PAS light behaviour makes (some) sense I think. If it does its self-checking fully before engine start and voltage going high, it probably doesn't spot the high voltage situation thereafter.  Not sure why ABS wouldn't be the same, maybe it has more thorough on-going self-monitoring; or maybe there's another fault in that system.

Position of the oil filter rather predisposes the alts on these to oiliness.

Am I right in thinking that with battery warning light coming on as normal and going out when engine starts that the wires are probably okay ?

That only confirms the intactness of the blue wire, I believe.

That only confirms the intactness of the blue wire, I believe.

Cheers, thanks again.

Got me wondering if my alternator is playing up if as I am getting similar warning lights, also the red handbrake light flashing.  Are you getting that too?

Got me wondering if my alternator is playing up if as I am getting similar warning lights, also the red handbrake light flashing.  Are you getting that too?

No, handbrake light seems to be working okay although I never normally drive this car. Will run around in it over next couple of days and see what happens.

I don't know what relevance the handbrake light has compared to the main two warning lights.

Yep, sounds like a voltage regulator failure to me too. On the back of the alternator, under the black plastic cover.  Not sure how readily available or costly the module might be though vs 2nd hand alternator.

If you have a look at any part numbers you can see on the alternator, I can have a look at a spare I have at home later, and if it's the same, read off any part numbers from the volt reg for you.

 

My understanding is that the load sensing wire is just that *sensing*, not controlling; so even if it's broken, the alternator will still do the same thing, it's just the ECU won't know what's going on, nor be able to pass on true info via CANbus to other modules. The ECU might default to assuming 'max load' in the absence of a signal though, so well worth checking carefully for wiring continuity if possible. It's the non-blue wire.

Well, at least on the Octy, if the sense wire breaks, the effect is to shut the alternator down. That makes me think it should be ok.

I don't know what relevance the handbrake light has compared to the main two warning lights.

Could you be leaving the hb one click on, or could it be slightly out of line with the switch?

Definitely not. light is out but it always comes on same time as abs and asr once I induce wheelspin.

Definitely not. light is out but it always comes on same time as abs and asr once I induce wheelspin.

I'll have a think; asking the b100dy stupid questions first can save time.

My mate is sure it's an electrical gremlin. My usual fuse box that would be on top of the battery is exposed to atmosphere and looks a bit manky. Wouldn't be surprised if that is the reason.

For what it's worth here's the part number of my spare alt, same as what's on the car, and a picture of the voltage regulator assembly, held in by 3 M4 hexheads, viewed with the outer black endcover removed:

 

 

 

Pink square seems to enclose what looks like a Valeo part number for the regulator:

 

I think I need to look out for a decent alternator for mine.  I may just buy new next time.  I forget where the current one came from but it was second hand and has only lasted (assuming it's at fault) about 2 or 3 years.

Thanks again Wino, that's useful as I might look at getting just a regulator. Not sure yet if mine is a 90 amp or a lower powered one. Car is a Classic, no electric windows, central locking or air con.

Quick look on ebay for that Vale part number - £54

Edited 16 February, 201511 yr by classic

Yours may well be a 70A alt then, I should think. No idea if that means the voltage regulator will be any different.  Of course it may not even be a Valeo alt, could be Bosch.

 

£54 not exactly a bargain.

 

You may be able to find out which alt was factory fitted via the option codes on the vehicle data sticker (in the front of the service book, or on boot floor), there's a de-coding list here. Alternator specs start with 8G (pdf page 89). A 90A one is 8GD, a 70A one 8GM, apparently. Only gives current rating though, not manufacturer.

Thanks again Wino, that's useful as I might look at getting just a regulator. Not sure yet if mine is a 90 amp or a lower powered one. Car is a Classic, no electric windows, central locking or air con.

Quick look on ebay for that Vale part number - £54

I think it will still have electric PAS and HRW though? Those are the 2 heaviest drain items (aircon uses a direct gas compressor), so what an alternator would be sized for.

I just thought - VCDS will tell me my running and static battery outputs.  Why didn't I think of that before? :(

Yours may well be a 70A alt then, I should think. No idea if that means the voltage regulator will be any different.  Of course it may not even be a Valeo alt, could be Bosch.

 

£54 not exactly a bargain.

 

You may be able to find out which alt was factory fitted via the option codes on the vehicle data sticker (in the front of the service book, or on boot floor), there's a de-coding list here. Alternator specs start with 8G (pdf page 89). A 90A one is 8GD, a 70A one 8GM, apparently. Only gives current rating though, not manufacturer.

Turns out it is a 90 amp, I have found new (non ebay !) regulators for a lot less than £54, but looking at the state/age of the current alternator I don't think it warrants a new voltage regulator.

Same part number as the one I've pictured?

 

I'd be willing to 'lend' you the voltage regulator off that one, if you're not beyond the reach of Royal Mail 'normal' rates?

 

If it solves your problem, just buy me A.N.Other volt reg at your leisure, if it doesn't send it back.

 

Although your current alt may look terrible as a result of oil spillage during filter changes, I doubt that it does it much harm.

Same part number as the one I've pictured?

 

I'd be willing to 'lend' you the voltage regulator off that one, if you're not beyond the reach of Royal Mail 'normal' rates?

 

If it solves your problem, just buy me A.N.Other volt reg at your leisure, if it doesn't send it back.

 

Although your current alt may look terrible as a result of oil spillage during filter changes, I doubt that it does it much harm.

That is a very kind offer, I've got to look at the part numbers to be sure they're the same, and car is out and so can't check until tomorrow. The regulators I've seen on T'internet probably aren't genuine Valeo so wouldn't want to short change you !