hey everyone new to the site so like to say hi first. my problem is i parked my car up in the night with no problems when i went to start the car it was like the battery was dead managed to bump start the car but the pas warning lamp was illuminated with no loss in power steering. when i tried to start the car after a 10 min drive it was the same so bumped it again but after 5 mins of driving i lost power steering and lights went dim. car is fabia 1.4 8v new battery fitted last month also the car wont even turn over or make any sort of noise. anyone help please

by looking at the forum does anyone think it could be the load signal wires?

yes m8 could be go to a garage and have alternator tested 

Yeah I had the same problem. Jump started it and it seemed ok. But problem soon reappeared. I checked the load wire and it was snapped. I replaced the wire and now all seems fine. My battery light actually shows when I turn the ignition. If you are handy have a go its a small quick fix.

is the load wire the two pin connector off the back of the alternator? i took this wire off the car and tested it from plug to plug and it seems fine. battery voltage is 12.5 and increases to 13.4 when started but wont increase with rpm and under load drops to 12.4. could it be alternator diodes on there way out? 

is the load wire the two pin connector off the back of the alternator?

 

No it's underneath near the starter motor. Looks like this....

 

It does originate at the two pin plug on the back of the alternator. The blue wire is the exciter, the brown one is the load sense wire. Bear in mind that these wires commonly break on both sides of the connector pair down on the gearbox bracket, so you haven't fully tested by just going from there to the alt connector.

 

I'm thinking that you may (also) have a different issue if the starter motor doesn't even try to turn (when there's some charge in the battery). There's a wire that very commonly falls off the starter motor solenoid; shown here:

 

 

The plastic insulation cracks where it turns that sharp corner at the red arrow. This lets in the atmosphere, which gradually turns the copper into whatever the green stuff is that it turns into. Then it snaps completely.  Happened to this car in the picture only a couple of weeks back.  Will probably happen to almost every Mk1 Fabia at some point.

It does originate at the two pin plug on the back of the alternator. The blue wire is the exciter, the brown one is the load sense wire.

 

 

Very true. I just meant it normally breaks at the underneath bit in my pic.

is the load wire the two pin connector off the back of the alternator? i took this wire off the car and tested it from plug to plug and it seems fine. battery voltage is 12.5 and increases to 13.4 when started but wont increase with rpm and under load drops to 12.4. could it be alternator diodes on there way out? 

 

Those alternator readings are low, suggest you replace the brush pack.

thanks for the replies. il have to check the wires at the other side of the connectors also the one wire in the pic above had been taped up but comeapart as soon as i touched it so repaired that wire. also noticed when i first start the car voltage is 13.4 but after 5 mins it has dropped to 12.8

those readings are at idle with no load. looking to get a brush pack but need it for tomorrow as i use the car for work.

thanks for the replies. il have to check the wires at the other side of the connectors also the one wire in the pic above had been taped up but comeapart as soon as i touched it so repaired that wire. also noticed when i first start the car voltage is 13.4 but after 5 mins it has dropped to 12.8

I haven't tried this myself, but I have a fair bit of confidence that it should work:

 

If you unplug the two-pin connector from the alternator, and measure dc voltage on each of the pins in turn relative to ground / batt negative (with ignition on but engine not running) you should expect to see ~12V on the one the blue wire goes to , and ~5V on the one the brown wire goes to.  If either of these is 0V that wire is broken somewhere on its way there.

thanks will try this first thing

tested the wires this morning got battery voltage onblue wire but 0 on the brown wire. still cant find the other side of the plug by the starter is it in this location on the mpi engine?

As the blue wire seems OK, I'd tend to be blaming the voltage regulator/brushes as sepulchrave suggests. 

Not sure how the loom is all connected up on an mpi 1.4, but I do remember someone recently saying they found their load sense wire going to a multipin round connector, on its way to the ECU, I think. What year is the car? I have some wiring diagrams I might be able to glean something from.

its a 2000 wino and got a second hand alternator cheap so decided to fit it but now both wires have a voltage of 11.5v with ignition on no battery light and no charge with engine running. the wires have all been taped up where it joins the main loom and is a nightmare to try and separate it all. the brushes looked fine on my old alternator.im just confused how the brown wire has gone from 0 to the same as the blue wire maybe a split in both wires and there touching. any help will be appreciated

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Sorry, should have asked what engine code as well, but with the year I can make a start at finding relevant wiring diagrams.  It is quite possible that 11.5V is correct for the other wire on your car, but it seems a bit of a coincidence that it's exactly the same (Edit: with ignition off, and two pin connector unplugged from alt, do you get zero Ohms if you measure the resistance between the two connector pins? That would show you if the wires are shorting somewhere).  I checked my  '03 Polo yesterday and got the same 11.5 on the blue wire, and 4.5ish on the brown one.  It will either be pulled up to 5V or 12V within the ECU, but that may vary from engine to engine/ECU to ECU.  I'll see what I can find.

 

Odd that another alternator is still not charging despite the blue wire having what it should.

 

Have you checked the strip-fuses in the battery-box fuse compartment? There's one in there that would disconnect the alternator from the battery if broken/blown (farthest left one as viewed facing into the engine bay, I think).

 

Edit: For engine codes AZE or AME from Feb 2000, the DFM (aka 'load sense') wire is brown/red from the alt to the two pin connector at the gearbox, and then becomes lilac/green on its way to pin 13 of the ECU connector, I can't see any other intermediate connectors shown. 

...the brushes looked fine on my old alternator.

.

 

They should be fine, the brush pack contains far more than just brushes!

swapped the brush pack over and now have battery light. put voltmeter over battery and started and it give a reading of13.5 then slowly dropped to 12.6. what would cause the output voltage of the alternator to drop without any load? thanks for the info checked all fuses, going to check resistance over the two connector pins.

Sorry, I missed the bit where you said no battery light with the replacement alternator.

 

If the brushes on your original voltage regulator/brushpack are OK, then it must be a fault with the voltage regulator part, as sepulchrave says, sort of.

Or maybe the battery is just in a very low state of charge, so pulling a bigger recharge current than the alt can supply at idle revs? Does the 12.6V go up if you raise the revs?

 

Were the brushes a good length on the bit you've just pulled off the replacement alternator?

the brushes on the replacement were half the size of the brushes on my original alternator. is there any way to test the regulator?

Best test I can think of is to borrow a known good, fully-charged battery off another car, and then see if you still see the same behaviour. If the voltage still does the same 13.5>12.6 That would rule out my idea that the voltage is being pulled down by the battery being very flat.

 

But raising the revs well above idle should show an increase from 12.6V, with your existing stuff, if it is the battery pulling down the output of the alternator, because the alternator can produce a lot more charge current at say 2500 rpm than it can at idle revs.

Check the rectifier as well, that's also in the brush pack, measure any AC component in the voltage, it should be negligible, no more than 0.5V AC.

 

Voltage would be pulled low by a fully-charged battery, not a flattie, the ECU knows when the battery is fully charged and not pulling any current and will cut voltage to prevent gassing.

 

Put everything on and the voltage should jump back up.

battery is only 3 months old, charged the battery and left it 24 hours and it read 13.2v on voltmeter. when engine is revved above 3000 rpm there is no increase in voltage.

Must be sick voltage regulator then, and maybe brushes too short on the replacement? Were they less than 5mm?

 

Edit: actually that voltage is a bit strange. Fully charged battery, not connected to anything, 24 hours after charging should show no more than about 12.7/12.8V; or was that when in the car, engine running?