Alternator load signal wire

[Dazza95]

Hello,

 

I read on here that if the battery light doesn't come up briefly on ignition, it means your alternator load signal wire is broken

 

I can't remember my car ever showing the battery light when starting, in fact I only noticed it when I was sat in my car waiting for somoene and reading a thread on here! Anyway, I'd like to get it sorted as I don't fancy the battery dying on me

 

Would it be hard for me to fix the problem myself?

 

The most complicated thing I've done on my car is resetting the gearbox linkages so I am a bit worried I'll mess something up! I could take it to a garage but with me using my car for my job and being away from home most weekends, it is a lot of hassle.

 

Thank you

 

 

[Breezy_Pete]

I think it's only do-able from under the car really, so whether you can do it yourself depends on being able to get to the area safely.  This may be as simple as parking with one wheel up on a high kerb, but you certainly shouldn't work under the car with it supported only by the wheel-change jack.

 

Here's a photo of the wires going into one half of the connector-pair where the problem occurs.  Vertically below the starter motor on the front of the gearbox:

 

[SKYHAWK]

or if ur alternators naffed i got 1 £50 delivered genuine part 

[Dazza95]

I think it's only do-able from under the car really, so whether you can do it yourself depends on being able to get to the area safely.  This may be as simple as parking with one wheel up on a high kerb, but you certainly shouldn't work under the car with it supported only by the wheel-change jack.

 

Here's a photo of the wires going into one half of the connector-pair where the problem occurs.  Vertically below the starter motor on the front of the gearbox:

 

 

 

Thank you, I should be able to park the car with one wheel on a high kerb, what exactly do I have to do once I can get to the area safely?

 

Also, is there any reason I haven't had any trouble with the car given this fault? I do about 500 miles a week and haven't had any difficulty starting or anything, the car spends most of its time at around 2k or a bit higher. I see it's on the front of the gearbox; I had my gearbox reconditioned back in September so they may well have knocked it while removing the gearbox.

[SkUG]

if your revs go above 2500 the alternator will charge, i believe

[Breezy_Pete]

You're looking for a broken wire, and if you find one, you mend it.

 

I think symptoms tend to be most obvious if the car does a lot of short urban journeys at low revs. Under these conditions, the ECU needs to work hardest to manage the balance between current demands and alternator 'ability'. In your case, the alternator will be spinning nice and quickly most of the time, so no need for the ECU to be/get involved.

[Dazza95]

if your revs go above 2500 the alternator will charge, i believe

 

Hmm, that probably happens very briefly when accelerating on a slip road or overtaking. 80mph is about 2500rpm and I rarely get to do that with traffic how it is

[Dazza95]

You're looking for a broken wire, and if you find one, you mend it.

 

I think symptoms tend to be most obvious if the car does a lot of short urban journeys at low revs. Under these conditions, the ECU needs to work hardest to manage the balance between current demands and alternator 'ability'. In your case, the alternator will be spinning nice and quickly most of the time, so no need for the ECU to be/get involved.

 

Great, thank you

[bigpaul]

HI

Have fixed this previously on my 06 Fabia 1.4TDI and all OK. Tried to do the same on neighbour's car (55 Fabia 1.4TDI) - soldered in wire to replace both wires through connector (one wire was broken). However, fault still exists (no battery light and not charging unless revved).

 

Has anybody experienced breakages elsewhere on this load wire - maybe between this faulty connector and the alternator, or the ECU (presuming that is other end)? Plug going into alternator itself looks OK and sound.  When it kicks in, alternator is generating 14.4V across the battery.

 

Cheers

Edited 13 December, 2014 by bigpaul

[NathanG]

HI

Have fixed this previously on my 06 Fabia 1.4TDI and all OK. Tried to do the same on neighbour's car (55 Fabia 1.4TDI) - soldered in wire to replace both wires through connector (one wire was broken). However, fault still exists (no battery light and not charging unless revved).

 

Has anybody experienced breakages elsewhere on this load wire - maybe between this faulty connector and the alternator, or the ECU (presuming that is other end)? Plug going into alternator itself looks OK and sound.  When it kicks in, alternator is generating 14.4V across the battery.

 

Cheers

 

Yes mine was broken else where.  I done a continuity test all the way along the wire until it disappeared in the bulk head.  Trace the wire all the way back under the batter, into the loom and then it disappeared.  So i ran a total new wire from the connector through the loom, through a grommet in the passengers side bulkhead, through the dash and into the black box under the steering wheel.

[wilsy7]

I was getting a fault code for this as well, i had the car on the ramp tonight to have a nosy. All appeared to be ok however I'm not entirely sure i was looking at the correct connector? the connector i was looking at was brown in colour and the wires leading into it were a different colour than those coming off the alternator from the top so almost certainly a different connector. It was located just back from the edge of the bumper (where the under tray and bumper meet) on the passenger side and was the first connector visible and easy accessed. Saying this i couldn't see anything else reasonably close? is the picture in post no: 2 from the top or the bottom? 

 

I've cleared the faults on VCDS and re scanned numerous times and it hasn't appeared again but I'm still not convinced as there is no battery light on the dash what so ever at any time. Can anybody confirm if i was looking at the correct connector or not? i don't think i was haha

 

Many thanks

 

 

Jordan

[SKYHAWK]

i bought this the other day if it helps

 

http://www.ebay.co.uk/itm/271548539287?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

think it ties in to your problem

[vzo25]

@wilsy7

After driving my car for 15min or so i kept having the asr light come on and stay on. So like you i investigated

The connection had been lost further back.where 1 wire had completely snapped and the other was just hanging by thread

Had to get a solderin iron to it.bit fiddly then put black tape on it.that was 6 month ago.dont have a prob

But def think youve got right connector

[okcharlie]

Thank you, I should be able to park the car with one wheel on a high kerb, what exactly do I have to do once I can get to the area safely?

 

Also, is there any reason I haven't had any trouble with the car given this fault? I do about 500 miles a week and haven't had any difficulty starting or anything, the car spends most of its time at around 2k or a bit higher. I see it's on the front of the gearbox; I had my gearbox reconditioned back in September so they may well have knocked it while removing the gearbox.

Hi there, I too have no battery light on my fabia and I am having charging issues, just wondered if you managed to find the fault?

Thanks in advance.

[okcharlie]

I think it's only do-able from under the car really, so whether you can do it yourself depends on being able to get to the area safely.  This may be as simple as parking with one wheel up on a high kerb, but you certainly shouldn't work under the car with it supported only by the wheel-change jack.

 

Here's a photo of the wires going into one half of the connector-pair where the problem occurs.  Vertically below the starter motor on the front of the gearbox:

 

 

 

I think it's only do-able from under the car really, so whether you can do it yourself depends on being able to get to the area safely.  This may be as simple as parking with one wheel up on a high kerb, but you certainly shouldn't work under the car with it supported only by the wheel-change jack.

 

Here's a photo of the wires going into one half of the connector-pair where the problem occurs.  Vertically below the starter motor on the front of the gearbox:

 

Hi there, you sound very knowledgeable on the subject, I also have no battery light on my 02 fabia 1.9TD and am having charging issues, new battery, new alternator etc. from your experience is there one wire colour in particular that tends to snap/frey? Thanks in advance.

[TMB]

Either wire can snap, or both of them as in this pic...

 

[okcharlie]

Either wire can snap, or both of them as in this pic...

 

Thanks for the quick reply, and the photo, didn't expect this sort of thing from a german company!

[wilsy7]

I think it's only do-able from under the car really, so whether you can do it yourself depends on being able to get to the area safely. This may be as simple as parking with one wheel up on a high kerb, but you certainly shouldn't work under the car with it supported only by the wheel-change jack.

Here's a photo of the wires going into one half of the connector-pair where the problem occurs. Vertically below the starter motor on the front of the gearbox:

Is this picture from above or below?

[Lofty]

That pic is from below looking up.

 

I bypassed the connector totally on mine.

[Breezy_Pete]

Is this picture from above or below?

That is the view from above. The rusty thing right at the top of the photo is the main casing of the starter motor.( Or maybe the starter solenoid on top of that?)

 

Hi there, you sound very knowledgeable on the subject, I also have no battery light on my 02 fabia 1.9TD and am having charging issues, new battery, new alternator etc. from your experience is there one wire colour in particular that tends to snap/frey? Thanks in advance.

I think it's the blue one that - if broken - results in no battery light, and an alternator that doesn't start charging as it should. The other one is actually the load sense wire, which, as far as I understand it, is a signal telling the ECU how hard the alternator is working, on a scale of 0-100% of its capability. This allows the ECU to make adjustments to fuelling/timing/throttle position to compensate for the engine load that the alternator causes, and so keep a steady idle speed, or even to disable some current consumers if there isn't enough current available. 

 

I'm still learning about this stuff, but that's my understanding at this time.

[okcharlie]

That is the view from above. The rusty thing right at the top of the photo is the main casing of the starter motor.( Or maybe the starter solenoid on top of that?)

 

I think it's the blue one that - if broken - results in no battery light, and an alternator that doesn't start charging as it should. The other one is actually the load sense wire, which, as far as I understand it, is a signal telling the ECU how hard the alternator is working, on a scale of 0-100% of its capability. This allows the ECU to make adjustments to fuelling/timing/throttle position to compensate for the engine load that the alternator causes, and so keep a steady idle speed, or even to disable some current consumers if there isn't enough current available. 

 

I'm still learning about this stuff, but that's my understanding at this time.

Many thanks, looks like I will be out with the multimeter, is it possible to check for continuity on the wires between the alternator and gearbox  coupling?

[Breezy_Pete]

Possible, yes, but not ever so easy. The connector on the alternator is about as accessible as it could be from above (on our 1.2, other engines may differ), but I still struggle to get my hand(s) in there enough to release the latch on that:

 

 

If you can get that unplugged, testing the blue wire connectivity should just be a matter of looking for approx. 12V on the pin of the two-way connector that the blue wire finishes at, with ignition switched on. If it's not there, then you'll have to remove whatever plastic undercovers might be in the way of getting to the connector pair on the gearbox bracket, and tracing back until you find the break.

[wilsy7]

Got this fixed today on mine, what an absolute ball ache to get at from underneath lying on the ground lol the piping for my FMIC took up the space that would have been there originally.

Battery light now back on dash and generator loading showing in VCDS. Cleared the fault so will continue to check for next day or two. Hopefully it all holds up. Fingers crossed

[Breezy_Pete]

  Well done that man.

[okcharlie]

  Well done that man.

 

  Well done that man.

Yes, well done indeed! I haven't had a day off work yet to test/trace mine but hopefully will have some success. Thanks again Wino for the photos and sharing your wisdom.