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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10628
  
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Alternators can fail in lots of ways.
They can stop charging.
Then can short the battery and cause it to go flat within 1 hour. Ok, yours isn't that bad, but you get the point. Just because it charges, doesn't mean it's not the issue
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 14th Dec 2022 8:17 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10628
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Moleshome wrote:
To test the fuse take it out of the meter and with the test leads in the 2nd and 3rd terminals clip them together to confirm that you've removed the correct fuse. Assuming you got a beep clip the leads across the fuse you removed. If you didn't get a beep by clipping the leads together you took out the wrong fuse.
I was doing a cleaver test where by you can test the fuses without removing the rear cover.
If you think about it. 10A is connected to COM via a fuse.
So if you connect the V terminal to the 10A, on the continuity setting, it should beep with a good fuse, because COM is connected to 10A via the fuse.....
Do you understand ?
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| 14th Dec 2022 8:20 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
 
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Ok ill try to test again tomorrow from scratch with a repeat video.
If it works, ill do the same again and bridge the starter and plus terminal. And split charge just in case.
Failing that, I’ll examine the alternator wiring when I do my viscous fan. Which is coming tomorrow. But also a busy few days.
Thanks Disco 3 SE Manual 2005 V6 2.7
Buckley, North Wales
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| 14th Dec 2022 8:25 pm |
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Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
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Pete K wrote:Alternators can fail in lots of ways.
They can stop charging.
Then can short the battery and cause it to go flat within 1 hour. Ok, yours isn't that bad, but you get the point. Just because it charges, doesn't mean it's not the issue
Exactly.
Also the fuse test method you mentioned is the way manufacturers such a Fluke recommend it's done.
OP, don't take this the wrong way, you appear to be 'pecking' at things to check rather than looking at results and developing a diagnosis path from them. If this has been going on for a year, then TBH, take a step back, stop thinking of what the cause is and go back to first steps.
DTC read
Battery test
Charging test
Current draw - over a period of time and on all consumers.
Evaluate the results once you have them all, not just part of the jigsaw.
In all honesty, I don't think you're going to be able to do a proper, long term current draw test with the multimeter you have.
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| 14th Dec 2022 8:43 pm |
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Moleshome
Member Since: 15 Oct 2020
Location: Wokingham
Posts: 412
 
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Pete K wrote:
I was doing a cleaver test where by you can test the fuses without removing the rear cover.
If you think about it. 10A is connected to COM via a fuse.
So if you connect the V terminal to the 10A, on the continuity setting, it should beep with a good fuse, because COM is connected to 10A via the fuse.....
Do you understand ?
The diagram on the front is simply a diagramatic representation of which terminals need to be connected based on what is being measured, if they were actually connected that way internally nothing would work because it would all be shorted to ground.
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| 14th Dec 2022 8:44 pm |
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Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
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That was my point, the schematic isn't clear, the line between the mA and the V appears to be a 'hop' as used in standard wiring diagrams to indicate a crossover rather than a connection in some of the photos but could equally be an angled connection line. I'm sure it would be made clear in the user manual but I can't find it online.
Some of my meters measure current between the COM and the current terminal, some are between the + and the current terminal dependent upon manufacturer so there is no real 'custom & practice' specifying which it will be.
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| 14th Dec 2022 9:01 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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Apologies I’ve literally zero experience on electronics. I’ve been going off all kinds of information over a few groups and this website, the information conflicts a lot and half the time it’s half informed guesses.
It’s not helped having diagnosis from friends either such as buy a new battery. At that point I’d never even used a multimeter to test a battery. So all these terms I’m having to Google haha
There are so many variations on the device etc and in between waiting for replies and conclusions, I am also checking wiring which I knew was a mistake but I did it anyway and wasted a day.
I have to swap my viscous fan any day now anyway so there’s no harm in me inspecting the alternator wiring condition visually while I’m there. Disco 3 SE Manual 2005 V6 2.7
Buckley, North Wales
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| 14th Dec 2022 10:01 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10628
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Well don’t read Facebook to save yourself time 
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| 14th Dec 2022 10:10 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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True that Disco 3 SE Manual 2005 V6 2.7
Buckley, North Wales
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| 14th Dec 2022 10:15 pm |
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Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
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Again, don't take this the wrong way - it's not 'electronics' it's just basic electrical circuits - voltage and current measurements are all you need to do, the only difference to a battery, switch and lamp circuit is that some consumers are permanently connected, hence the quiescent current draw. Other items (such as the alternator for example) which are permanently connected, may draw current when there is an internal defect, others, such as the EAS may draw current sporadically but intentionally. On top of that, there may be other defects that cause current draw on a completely different circuit to the one with the defect.
An example: Recently we've had a vehicle that was suffering sporadic flat battery concerns, we've had it parked in the workshop for two weeks with no issues, the customer took it back and within two days the battery was flat again. The vehicle has a tracker (manufacturer approved) fitted and the home address is in a valley well out of 'civilisation', so we disconnected it - no change. We ran dataloggers on various modules supply , found the central gateway & connectivity modules were waking sporadically but with no usual triggers. After a few more days and whilst checking the data connections, we found that two data pairs had been crushed due to a mis-routed harness at build, this was coincidentally where the drivers heel rested and whilst the insulation was not wholly compromised, it was measured in kilo-Ohms not Mega-Ohms.
The point is, the defect isn't always where it's indicated and the root cause needs to be 'reverse engineered' in some cases, this was due to wiring being crushed over 18 months of usage and the weight of the drivers heel manifesting itself in lost comms between two modules that normally quietly communicate when the vehicle is shut down causing them to noisily communicate (and draw current) when they could no longer talk.
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| 14th Dec 2022 10:31 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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Thank no offence taken
It’s the gathering of information that’s been hard. And learning the multimeter settings and how delicate it is.
But now knowing the settings, it does indeed seem simple
On that note, I did a repeat test like the successful
One on my YouTube BUT not getting any readings. Does this mean I need another multimeter? Or does my new below video show I’ve done something wrong?
The alarm goes off if the cars locked also. Where as I swear it didn’t on my original video. Or maybe it was unlocked but I’m certain it was locked!
Here you go:
https://youtube.com/shorts/tXcUQU8Ook0?feature=share
I do have a gps installed, but it only powers up when ignition is on. It’s piggy backed from the 12v socket fuse. Disco 3 SE Manual 2005 V6 2.7
Buckley, North Wales
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| 15th Dec 2022 2:47 pm |
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Flatlander
Member Since: 20 Jul 2015
Location: Here
Posts: 575
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Right, well the connection is correct and the meter settings and lead positions appear correct so if the alarm is going off and there is a reading of zero on the meter, it's reasonably safe to conclude that the fuse on the 200mA input has blown - when you reconnected the power to the BJB was there a bit of arcing?
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| 15th Dec 2022 6:49 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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I’m going to buy new multimeter tomorrow and hopefully some spare fuses
Sorry I should have figured that out sooner
Must have blown it when doing the main chunky wire which I presume is the starter wire.
In that event, won’t it just blow again on the same cable or maybe it was because I did it wrong.
I won’t even bother getting a bolt reading tonight I already know the answer
Will update tomorrow day got few hours to have a look
Thanks as always Disco 3 SE Manual 2005 V6 2.7
Buckley, North Wales
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| 15th Dec 2022 10:46 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10628
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So if you bridged the gap with the meter before separating (like you did the first time) and it blew then that suggests over 200ma was flowing down it and explains why you have a flat battery.
On a new meter you could use the 10A connection to avoid blowing things and get a reading
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| 15th Dec 2022 10:53 pm |
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