What Do You Make Of My Alternator

[bus_boy]

Hi All,

 

I'm up creek again, this time it's alternator.

 

It failed to start a couple of times and needed either a jump or an external charge.

12.6V on battery, 12.6V on battery with engine running. ;) I've had the battery drop tested and it's in the green.

So I pressed ahead with alternator replacement.... Friday afternoon.

 

The Bosch part number on my busted alternator is 028 903 028 E, it's rated 120A. My car is a 1.9TDI Mk2.

 

I have just purchased and fitted a Lucas eqiv device purchased from Euro Car Parts this morning for

[daran71]

Hi All,

 

I'm up creek again, this time it's alternator.

 

It failed to start a couple of times and needed either a jump or an external charge.

12.6V on battery, 12.6V on battery with engine running. ;) I've had the battery drop tested and it's in the green.

So I pressed ahead with alternator replacement.... Friday afternoon.

 

The Bosch part number on my busted alternator is 028 903 028 E, it's rated 120A. My car is a 1.9TDI Mk2.

 

I have just purchased and fitted a Lucas eqiv device purchased from Euro Car Parts this morning for

[bus_boy]

Hi Daran,

 

If the + ve side of the alternator is the where the heavy cable is connected, then yes i've checked it. All I get is the 12.6 ish V that get at the battery (with engine running of course).

 

I too have replaced a starter about a year ago. I did check cables, but there is a lot of road dirt in that area!

 

Andyb

[mikej]

Check the small fuse box on the other end of the heavy cable, it's on the right hand side of engine bay next to battery and shold have a thick red wire coming from it to battery, these are very prone to meltdown due to loose connections on the fusable links inside ( like many others i had to change mine ) if this is the problem this could cause the light to stay on as it did with mine before catching fire lol it would also explain the lack of charging.. ;) Edited July 11, 2009 by mikej

[daran71]

Hi Daran,

 

If the + ve side of the alternator is the where the heavy cable is connected, then yes i've checked it. All I get is the 12.6 ish V that get at the battery (with engine running of course).

 

I too have replaced a starter about a year ago. I did check cables, but there is a lot of road dirt in that area!

 

Andyb

 

If you are only getting 12.6v at this point on the alternator I would suspect that could be at fault - an alternator should be pushing out around 14v!!

[bus_boy]

Thanks for the advice guys.

 

I guess i'll have to get back to the shop for replacement unit now.

;)

[bus_boy]

Oh dear, replacement unit now fitted (in rain, deep joy). Apparently it is a better quality one. I'm getting quite good at this task now!

 

This one does not make any loud buzzing sound from behind the dash, but now my dashboard battery light is on all the time ;)

 

 

With engine running and lights on last night the batter voltage rose slowly to 13.5V. This morning on same test it fell to 9.6V rose a little then fell. I assume this all down to battery and chemicals etc... looks as if my alternator is not contributing.

 

I have ran a VAG-COM over it and got nothing back of interest.

 

Does anyone know of any weak connections or fuses in main box i need to look at? The ones in the battery junc box are all fine.

 

Also, what are all those connectors underneath the battery junc box? Should I have a rummage in there?

 

Cheers all.

[mikej]

Quote

 

Does anyone know of any weak connections or fuses in main box i need to look at? The ones in the battery junc box are all fine.

 

Also, what are all those connectors underneath the battery junc box? Should I have a rummage in there?

 

 

They may look alright but are the fuseable links all tight ?

Edited July 15, 2009 by mikej

[iluvm]

Are you getting good continuity between the alternator terminal and battery terminal?

 

And then do you still get good continuity while you pull/yank the connecting cable?

 

I had loads of trouble with the fuse link box (melted) on battery and cable had started to melt.

 

Might sound silly but are your brake lights working? The brake light switch on my galaxy blew when I had trouble with with fuse link/battery, may have nothing to do with it but don't take a second to check.

[Smilge]

Above post has probably hit the nail on the head. There's a good chance your main cable from the alternator to the fuse box has overheated at some point due to high resistance, and this is the cause of your 9.6V while the engine is running. I would replace not only this cable but also the main earth and clean all interconnections. You need to do this ASAP before you end up having to replace the alternator again and end up with a melted fuse box and possible engine bay fire.

 

Hope this helps

[turk90210]

From reading your posts I assume you have access to a digital multimeter (DMM) if so you can follow the test sequence below to check your alternator

 

Firstly check the batt warning light circuit (IND Wire) basically disconnect the small wiring plug to the alternator, identify the ind wire and with the ignition turned on (engine NOT running) use the DMM to see if you have battery voltage (IIrc the other wire is an output to the revcounter on the diesel models) if you have voltage earth the wire to the body of the alternator and see if the battery warning light comes on,if it does that circuit is ok if not check the wiring or dash bulb

next, to check the output of the alternator you need to eliminate the earths first, this is quite simple with the DMM

with the meter on dc volts place one probe onto the battery earth then with the other place it to the body of the alternator (make sure the engine is running and if poss put a load on to make the alternator work, ie turn head lights on). If the earth is good you should see a value of no more than 0.5volts. if you have a higher voltage you have a poor connection and it is just a case of following your earth back and keep checking with the meter when you suddenly come to a point where you jump from a high to low reading that is your bad connection and needs cleaning, once rectified re check to confirm

next you can apply the same principle to the positive side, place one lead to the positive post on the battery and check the big lead on the alternator and work your way back along that lead, the same voltage rules apply big volts poor connection, low(0.5) good connections. If all that proves ok do a final check the normal way round with the DMM, black lead to neg(on battery or engine),red to positive and confirm voltage output at the battery,fuse box back of alternator and at the starter where the 2 leads meet, if it is still poor then it looks like a faulty alternator,

Poor connections on any consumer unit can be checked this way BUT remember that the consumer unit HAS to be working/switched on or attempting to work

As someone has mentioned the fuseboxes by the battery are common faults as well as the wire overheating and creating a high resistance, testing for continuity in itself is not a good indication I think the poster meant to say check the resistance but if the value cannot be checked against a known good one then this is a good confimation test

 

Everyone has there own opinion on Eurocar parts good and bad with some of the parts they sell from experience mine is mixed, that said I do have a concern with yours re the first alternator creating the buzz behind the dash now the 2nd has been fitted the buzz has gone BUT the warning light stays on I hope its just co-incidence

Also the warning light circuit is to excite the alternator to charge at a low revs so theoretically if the alternator is ok (but has a warning light fault) if you rev your engine to 2000-3000rpm briefly the alternator should self excite and start charging as normal

Try the test above and post back your results, personally my money is on a faulty alternator still

[davetee]

From reading your posts I assume you have access to a digital multimeter (DMM) if so you can follow the test sequence below to check your alternator

 

Firstly check the batt warning light circuit (IND Wire) basically disconnect the small wiring plug to the alternator, identify the ind wire and with the ignition turned on (engine NOT running) use the DMM to see if you have battery voltage (IIrc the other wire is an output to the revcounter on the diesel models) if you have voltage earth the wire to the body of the alternator and see if the battery warning light comes on,if it does that circuit is ok if not check the wiring or dash bulb

next, to check the output of the alternator you need to eliminate the earths first, this is quite simple with the DMM

with the meter on dc volts place one probe onto the battery earth then with the other place it to the body of the alternator (make sure the engine is running and if poss put a load on to make the alternator work, ie turn head lights on). If the earth is good you should see a value of no more than 0.5volts. if you have a higher voltage you have a poor connection and it is just a case of following your earth back and keep checking with the meter when you suddenly come to a point where you jump from a high to low reading that is your bad connection and needs cleaning, once rectified re check to confirm

next you can apply the same principle to the positive side, place one lead to the positive post on the battery and check the big lead on the alternator and work your way back along that lead, the same voltage rules apply big volts poor connection, low(0.5) good connections. If all that proves ok do a final check the normal way round with the DMM, black lead to neg(on battery or engine),red to positive and confirm voltage output at the battery,fuse box back of alternator and at the starter where the 2 leads meet, if it is still poor then it looks like a faulty alternator,

Poor connections on any consumer unit can be checked this way BUT remember that the consumer unit HAS to be working/switched on or attempting to work

As someone has mentioned the fuseboxes by the battery are common faults as well as the wire overheating and creating a high resistance, testing for continuity in itself is not a good indication I think the poster meant to say check the resistance but if the value cannot be checked against a known good one then this is a good confimation test

 

Everyone has there own opinion on Eurocar parts good and bad with some of the parts they sell from experience mine is mixed, that said I do have a concern with yours re the first alternator creating the buzz behind the dash now the 2nd has been fitted the buzz has gone BUT the warning light stays on I hope its just co-incidence

Also the warning light circuit is to excite the alternator to charge at a low revs so theoretically if the alternator is ok (but has a warning light fault) if you rev your engine to 2000-3000rpm briefly the alternator should self excite and start charging as normal

Try the test above and post back your results, personally my money is on a faulty alternator still

Interesting thread I replaced my alternator after pulley failure and ran the car for a couple of months no problem the battery needed replacing as it was getting a bit lazy after fitting a new battery straight away loud bussing (relay) and battery light on and no charge to the battery now if you turn the ignition key quickly when starting the car the battery light goes out and the battery charges how strange is this ??

[Rusty Nail]

I would go with the masses and change the small fuse box and alternator lead.

 

I did!

 

It doesn't take long, doesn't cost much and I'm sure it will solve your issues.

The problem is within the crimp of the main cable from the alternator and the fuse box. The elements get to the the fuse box crimped end causing a higher resistance and so the cable heats up (vicious circle starts). This can cause the fuse box to melt as mine did, and or cause bad connections all round from this point as the fuse links become loose or worse - and it's the main point between the battery and alternator. Not all of this with the damage is visually noticeable and so will need checking with a DMM as per turk90210's post

 

Good luck and be quick.....