goodo
Member Since: 04 Dec 2018
Location: Cheltenham
Posts: 96
  
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| Charging fault post earth strap repair - any ideas? |
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We had an issue where the car just didn’t start one day. No prior warnings, it just wouldn’t crank.
I heard a click.
I looked on here and someone (thanks!) mentioned that it might be an earth problem and to connect battery negative lead to engine. Engine started.
More research and I figured it was the earth strap. Car’s a TDV6 2010 with 140k
Local Indy Greyhill did a ‘fix’ where they attach a new section of cable, but they don’t replace the original as it’s a pig to do.
Anyway, picked up the car and now getting an intermittent battery charging fault and warning on the dash.
I’ve bought a new alternator, and I’m thinking about trying to fit it, but given how much if a pig the job is to do on this car, is there any chance this is something else and the alternator is fine?
The battery fault on the dash is intermittent. It comes and goes. I just checked the voltage at the battery with engine running 15.25V
Is this a faulty alternator, or something else? Don’t want to change it if there’s nothing wrong, but equally don’t want to get stranded….
Any ideas, suggestions?
Cheers
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 9th Jul 2023 2:23 pm |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12720
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I'd start by checking battery clamps are tight,
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| 9th Jul 2023 5:48 pm |
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goodo
Member Since: 04 Dec 2018
Location: Cheltenham
Posts: 96
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I wouldn’t say they clamp the terminals that effectively. Anything I can add to improve the circuit, grease?
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| 9th Jul 2023 5:59 pm |
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Admirable
Member Since: 19 Jul 2015
Location: Fife
Posts: 1013
  
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No grease, get a piece of emery paper or sandpaper, remove the battery clamps and clean the inside of them. Give the battery terminals a clean too.
Replace clamps and make sure they are tight.
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| 9th Jul 2023 7:18 pm |
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goodo
Member Since: 04 Dec 2018
Location: Cheltenham
Posts: 96
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Thanks, I’ve scuffed up the terminals, will see if it makes any difference. Do these alternators die gradually or suddenly?
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| 10th Jul 2023 8:00 am |
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Pedros
Member Since: 25 Jun 2011
Location: Cumbria
Posts: 454
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Had the earth cable thing happen to me. Trying to start it, with and without jump leads prior to the problem being diagnosed meant that the battery, despite being less than a year old was knackered. So, if you haven't, do check that out.
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| 11th Jul 2023 12:20 am |
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goodo
Member Since: 04 Dec 2018
Location: Cheltenham
Posts: 96
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Mmmmm. That would be annoying if the battery needs replacing too. How would I check? What’s the normal range for an alternator? Last alternator (I checked the records), lasted 80k miles. Now at 140k.
Cheers
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| 11th Jul 2023 7:48 am |
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NC500
Member Since: 18 Sep 2017
Location: On the NC500
Posts: 497
 
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Alternator life: difficult to predict. Mine is a 2014 on 150k still with original. My wife’s Toyota is 22 years old, 110k and still on original. My Ford is 23 years old, 70k and is on its 3rd!!
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| 11th Jul 2023 8:15 am |
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Gary_P
Member Since: 03 May 2016
Location: Kent
Posts: 1524
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goodo wrote:Mmmmm. That would be annoying if the battery needs replacing too. How would I check? What’s the normal range for an alternator? Last alternator (I checked the records), lasted 80k miles. Now at 140k.
Cheers
Charge to battery should be around 14.5v when engine is running. Gary
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Discovery 4 HSE 2016MY
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| 11th Jul 2023 9:35 am |
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UNG
Member Since: 20 Jun 2008
Location: Lancs
Posts: 753
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If you have a multimeter I would check the resistance between the negative battery terminal and the engine ideally I try to get it to be around 1Ω or less when I have replaced earth straps on various cars.
In the past I have seen cars with starting problems where the resistance between the negative terminal and engine has been 5Ω - 8Ω so it only needs a slightly poor connection to cause problems "Never keep up with the Joneses. Drag'em down to your level. It's cheaper".
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| 11th Jul 2023 10:26 am |
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M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8115
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goodo wrote:Mmmmm. That would be annoying if the battery needs replacing too. How would I check? What’s the normal range for an alternator? Last alternator (I checked the records), lasted 80k miles. Now at 140k.
Cheers
It depends what you changed it with, none genuine have been known to fail within a week  although yours has the symptoms of a poor connection, but poor connections usually show up when cranking the engine. It can when others can't,
It will when others won't,
It goes where others don't.
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| 11th Jul 2023 10:54 am |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12720
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UNG wrote:If you have a multimeter I would check the resistance between the negative battery terminal and the engine ideally I try to get it to be around 1Ω or less when I have replaced earth straps on various cars.
In the past I have seen cars with starting problems where the resistance between the negative terminal and engine has been 5Ω - 8Ω so it only needs a slightly poor connection to cause problems
I've seen cars with the starter motor and earth cables broken within the plastic outer. On pure resistance they still looked "good-ish" because the broken ends were still making some contact ... but when you try shoving 100A down them, it doesn't work.
The above scenario could result in a Ford Cortina starter motor dropping in your face when it should have swung nicely on the cable. Ask me how I know ? 
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| 11th Jul 2023 11:34 am |
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goodo
Member Since: 04 Dec 2018
Location: Cheltenham
Posts: 96
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Alternator was replaced. Problem solved. Apparently the diode pack was faulty, probably done in when trying to bypass the faulty earth strap.
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| 1st Aug 2023 8:51 pm |
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MrNicotra
Member Since: 21 Jul 2023
Location: Central Belt, Scotland
Posts: 37
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Thanks for sharing. I am facing a similar situation - I think. Two questions:
How did you check for diode fault?
How did you check the earth strap?
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| 17th Aug 2023 12:38 pm |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12720
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Connect a jump lead between battery negative and engine.
If problems go away, it's the earth straps that need replacing.  .
Dean
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2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer  ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
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| 17th Aug 2023 1:09 pm |
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