The Triumph Dolomite Club - Discussion Forum

The Number One Club for owners of Triumph's range of small saloons from the 1960s and 1970s.
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 Post subject: Earth points
PostPosted: Wed Sep 12, 2018 8:11 pm 
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Joined: Mon Jan 05, 2015 12:42 pm
Posts: 231
Location: Ashington, West Sussex
Hello all! Hope you’re keepIng well.

My electrics are up the creek (without a paddle!!). For a few months now all my bulbs have been glowing mysteriously brighter when I drive along. They’ll all just pulse brighter for half a second! At first I thought Nina was just enjoying the music and getting a bit excited, but think maybe it’s a bad earth?

Secondly and more frighteningly, my IGN light is now on permanently. It dims a little at higher revs, but the voltmeter always comfortably reads 14v (with everything electrical off 3000rpm, sometimes over-reads). Alternator is <6 months, battery maybe a year old. Fan belt tight.

Thoughts? Where can I get a guide to earthing points please?

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"The harder the conflict, the more glorious the Triumph." - Thomas Paine

1975 TRIUMPH DOLOMITE 1850 in Honeysuckle (Nina)
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 Post subject: Re: Earth points
PostPosted: Wed Sep 12, 2018 8:39 pm 
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Joined: Sat Apr 12, 2014 10:02 pm
Posts: 2128
Location: Nr Kenilworth
It sounds to me like alternator problem again. Its worth checking earths though. Neg of battery should attach to the engine either via a chassis connection or straight to it. On a sprint, one part of the earth connection to the block is via the engine mount bolt on the N/s I think. Also worth remembering is the alternator itself MUST have a good clean connection to the engine too via the bolts from the engine to it. Quick dirty check is to attach a jump lead to the alternator body and the other end to the battery negative. If light goes out it'll be alt to block dirty connection. HTH

Tony

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 Post subject: Re: Earth points
PostPosted: Thu Sep 13, 2018 10:05 am 
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Joined: Mon Aug 10, 2015 7:20 pm
Posts: 1192
Location: Huntingdon
Silicone diode rectifier pack is starting to break down, which causes over voltage hence lights being brighter and they pulse as the bridge rectifier is no longer intact and so you're getting an AC ripple. You're seeing the ignition warning light on because the normal zero point for the ignition light has been passed, it's normally balanced, but if not due to too little or too much charge it will light up, dimly usually but may get brighter or pulse as well.

Edit: Should say, this is noramly an easy job and cheap to replace if your alternator is otherwise in good condition, for example, assuming you havce the standard alternator: https://www.jcrsupplies.co.uk/products/ ... dvert.html

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Current fleet: Triumph Dolomite Sprint '75, Daihatsu Fourtrak, Honda CG125, Yamaha Fazer 600, Shetland 570

Disposal fleet: Golf GTi 16v MK3 Anniversary

Past fleet: Triumph 2000, Lancia Beta Coupe, BL Mini Clubman, Austin Metro, Vauxhall Cavalier MK1 & MK2, Renault 18 D, Rover 216 GSI, Honda Accord (most expensive car purchase, hated it on pickup from dealer, was made out of magnetic metal as only car I've ever been crashed into, 4 times), Golf GTi MK3 16v x 3


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 Post subject: Re: Earth points
PostPosted: Thu Sep 13, 2018 10:41 am 
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Joined: Mon Jun 11, 2012 3:36 pm
Posts: 835
Location: Andover Hants
If you are overcharging which it sounds like, be careful as it can cook your battery.

I had the same problem & on a 2 hour drive back from a show the battery spat acid out of the vent onto my newly painted engine bay!

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 Post subject: Re: Earth points
PostPosted: Thu Sep 13, 2018 1:18 pm 
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Joined: Sun Mar 16, 2008 2:52 pm
Posts: 1966
Hi Kyle, Remember we had your engine out some time ago ? As Tony says above, one of the important earth points is the one from the battery to the offside engine mount which we had to remove. Did we tighten it back O.K. ?
The other thing to check is since you have an early car ( N-reg ) you may still have the early wiring to the alternator.
This is one thin brown / yellow which is the IGN light connection, one thick brown wire which is the main +13.5V high current output and a third thin brown wire which is the early alternator "sense" output. It would be worth checking the connection of this wire. If it goes open circuit or high resistance the output voltage will go high.
On the other hand if you have 2 thick wires it is a "local sensed" alternator, so back to square one.
The quick solution is going to be swap the alternator for a new one, as the combination of high voltage on the battery gauge with IGN light on is unusual.
Tony.


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 Post subject: Re: Earth points
PostPosted: Fri Sep 14, 2018 3:41 am 
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Joined: Mon Jan 05, 2015 12:42 pm
Posts: 231
Location: Ashington, West Sussex
Ok so I cleaned up all the connections and earth points I could find (Tony I do have the early connection to the alternator), and the idle has improved & rose a good 300rpm, so clearly helped! Driving into work this morning, no IGN light, but it still appeared there faintly when I parked up at the end after I brought the idle back down to about 800!

Thinking the next best idea is the silicone diode rectifier pack - bloody frustrating though with a new alternator. I’m pretty sure I have a standard alternator, so should be straightforward! :)

Thanks!

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"The harder the conflict, the more glorious the Triumph." - Thomas Paine

1975 TRIUMPH DOLOMITE 1850 in Honeysuckle (Nina)
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 Post subject: Re: Earth points
PostPosted: Fri Sep 14, 2018 5:52 am 
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Joined: Fri Jan 08, 2016 9:00 pm
Posts: 875
There's a reason the spares for the original alternators are so easy to come by.......


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