yeah could pull those small reds see what happens

 

other than than that whats live and not fused...starter and alt is always live and no fuse not sure what else 

Edited 27 February, 20224 yr by steveo3002

You can detach the 3 red wires from the positive post by removing the nut, the thick one goes to the starter/Alternator.

 

it will at least discount the starter/ alternator if it’s ok with the 3 wires removed.

 

It’s a process of elimination  by methodical disconnection.

 

Regarding fuses you’ve pulled, according to the Haynes diagram I posted  previously, there should be 16 fuses in the fuse box and one above for the Fuel pump Lambda sensor, which is a 20A. To find a SC all the fuses should be removed at once and if the drain stops, insert them so you only have one in at a time to see which one(s) are feeding the culprit circuit.

 

If all fuses are out and the Starter/alternator circuits are disconnected and there’s  still a problem, it’s going to get a bit more complicated. 

Edited 27 February, 20224 yr by mk2tastic

try attaching the smaller reds and not the thick one.....thick one is starter/alt only 

Hi all,  reporting in with latest update.  I disconnected all positive side wires on battery. Each red connector split into 2. So 4 reds in total and one big black.  I set multimeter to 10A and ran it in sequence from battery to each red and then black separately. On one of the reds it was drawing 0.1A. 

The other red and black were 0. The battery is a new 45AH.

Please correct me if wrong but I'm assuming 0.1A draw is no where near enough to flatten my battery.  So I'm thinking has the intermittent fault gone at time of checking.  I'm going to leave multimeter connected on 20v setting across poles of battery and I'll see if it drops.  It normally ticks down very quickly. 

yeah i would expect to see 10 amp drawer or so 

 

with it all connected go around and wiggle the wiring , see if you can provoke it 

Cheers,  I was kind of coming to a similar figure.  I'll give it a try. 

0.1A or 100Milliamps is probably the permanent feed to the radio, so quite normal.A 2hr flattening of the battery will be a quite a hefty current draw, probably more than most of the fused circuits can cope with, so I’d still be tempted to think the problem is in the unfused Starter/Alternator Circuit, but that’s far from certain.

 

Check the thick cable from the Alternator back to the battery as well as from the starter to the battery. I think it will run under  sump in the Crankshaft pulley area. It might  be supported in a bracket on the sump, which it is on my earlier MK2. A chaffing or rubbing cable that has broken the insulation could be the cause of the problem.

 

When faults are intermittent they are a right pain in the ar*e to find, so I sympathise with you and the frustration it will be causing.
 

Keep us updated and we’ll keep trying to point you in the right direction, but by the sounds of it you are doing all you can with the disconnection routine.You just need to catch it whilst it’s failed.

Edited 1 March, 20224 yr by mk2tastic

yeah take a close look at that cable...its clipped to the metal sump so plenty of scope for rubbing through

Just a thought, it could still be the alternator diodes breaking down when they get warm/hot and then when cooled down return to normal, as I'm guessing you are doing most of the fault finding with a cold/cool engine ??

38 minutes ago, nige8021 said:

Just a thought, it could still be the alternator diodes breaking down when they get warm/hot and then when cooled down return to normal, as I'm guessing you are doing most of the fault finding with a cold/cool engine ??

Yes.  All checking being done with a cool or cold engine.   Is it an easy check to test the diodes? Bare in mind I've very little motor vehicle knowledge. 

1 hour ago, mk2tastic said:

0.1A or 100Milliamps is probably the permanent feed to the radio, so quite normal.A 2hr flattening of the battery will be a quite a hefty current draw, probably more than most of the fused circuits can cope with, so I’d still be tempted to think the problem is in the unfused Starter/Alternator Circuit, but that’s far from certain.

 

Check the thick cable from the Alternator back to the battery as well as from the starter to the battery. I think it will run under  sump in the Crankshaft pulley area. It might  be supported in a bracket on the sump, which it is on my earlier MK2. A chaffing or rubbing cable that has broken the insulation could be the cause of the problem.

 

When faults are intermittent they are a right pain in the ar*e to find, so I sympathise with you and the frustration it will be causing.
 

Keep us updated and we’ll keep trying to point you in the right direction, but by the sounds of it you are doing all you can with the disconnection routine.You just need to catch it whilst it’s failed.

Cheers.  Thankyou for all your help and advice.  It's really kind and I've been blown away with all the help and support from everyone.  I did notice that huge black wire underneath running from the alternator to battery? .  It was resting on a metal bar that connected to the wheels.  Anti roll bar?? I lifted it and it appeared wrapped in black tape along most of its length.  I didn't see any breaks or exposed wire but it had gone flat at the resting point on the bar,  whereas the rest of the cable appeared round. 

1 hour ago, steveo3002 said:

yeah take a close look at that cable...its clipped to the metal sump so plenty of scope for rubbing through

Thanks.  I have seen that Alternator wire.  It seems covered in black tape that all seems intact and undamaged but it was resting on a bar underneath.  

From 3pm today till now the voltage on battery hasn't dropped.  I've been waggling wires whilst multimeter set for amps drain and it never went above 0.1a which as someone has said,  appears normal.  It did occasionally drop to  0.05a then 0.07a then back to 0.1a. I presume that was me waggling wires that created this anomaly. So my conclusion is that it has entered that period where it runs ok for a short while.  Think it lasted 2 or 3 weeks last time but it cropped up again.  It's pretty annoying but I'm feeling better equipped to solve it now I've been fortunate enough to get all this great help and advice.  Thanks for all the time you've given so far.  

2 hours ago, Dragon10000 said:

Yes.  All checking being done with a cool or cold engine.   Is it an easy check to test the diodes? Bare in mind I've very little motor vehicle knowledge. 

Have a read of this https://www.clubpolo.co.uk/topic/335902-testing-your-alternator/#comment-2737019 

 

simplest way if you spot the drop happening is to undo the main wire on the alternator...put a piece of tape on it as it will be live 

Edited 2 March, 20224 yr by steveo3002

After Tuesday when the voltage didn't drop for 5 hours I thought it might go away again for a bit.  It was ok till about 6pm last night,  I went out to check and the battery was almost  flat, battery was warm but starter and alternator stone cold.  Everything i touched in the engine felt cold.  After charging and reconnecting I checked it again after work and it started dropping immediately. Dropping 0.01v every second or so.  I decided to test the amp draw again now it was happening.  Took off the reds and black and measured independently. Nothing.  0.0a. Reconnected terminals to battery and problem gone.  Voltage stable,  lower than originally obviously but not counting down. Its like the process of disconnecting the positive to test then Reconnected caused the issue to reset itself.  Or it could be a coincidence.  

it could well be making a relay reset

 

did you feel the rear screen?

 

 

Edited 3 March, 20224 yr by steveo3002

1 hour ago, steveo3002 said:

it could well be making a relay reset

 

did you feel the rear screen?

 

 

I did wonder about a relay but I don't understand enough to figure it out.  The rear screen cold.  This is now really bizarre thing.  So it was draining till I disconnected it and subsequently tested it,  then when no drain detected I reconnected the battery and voltage ok, so i took off neg whilst finishing recharge.  I carried on charging my battery till full.  Just reconnected everything,  put multimeter on and it's counting down in volts again.  Nothing has moved.  Car not been started. Nothing interfered with apart from either removing the neg or pos lead on battery.  

ok so go around and pull fuses , relays , radio etc...anything you can unplug

9 minutes ago, steveo3002 said:

ok so go around and pull fuses , relays , radio etc...anything you can unplug

Under the bonnet on right hand side of engine under the windscreen,  I took out every fuse in the little plastic case and the one above it.  I also removed the relays there.  Then in passenger footwell behind the glove box there were some more relays.  I removed those too.  The voltage still dropped.  I must add,  I disconnected the big wire and little red wire to the alternator too. It pointed to the starter in my opinion but I can't detect a drain when I try. 

how strange...im out of ideas

 guess it must be a bare wire touching sometimes ? 

First I'd like to thank you Steve. You've been really helpful.  It's a real puzzle.  I've paid a mechanic to have a look and he didn't know so it was sent to an auto electrician he recommended who couldn't find any fault ( I presume it was the intermittent bit) then it was ok for 3 weeks then started again.  I just don't get it.  It's not like it's a modern car. It still has wind up windows!

yeah very basic cars , with all the fuses and relays out i dont see what else there can be

 

all standard radio ? no add on wiring at all ?

 

is there 2 relays on the side of the ecu bracket?  tried those?  is the ignition coil hot when its doing it ?   

I've got no science to explain it, but I'm suspecting the rectifier pack on the alternator. 

32 minutes ago, Yeti said:

I've got no science to explain it, but I'm suspecting the rectifier pack on the alternator. 

says he pulled the wiring off it 

 

think id have that main battery cable off the car and inspect it carefully