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What puddle?



Member Since: 25 Oct 2013
Location: Reading
Posts: 952
United Kingdom 
Any auto electricians reading?
I have a 4-pin relay to add some spotlights that come on whenever main beams are on

Permanent live from battery at 30
Live out to spotlights at 87
Live in from main beam circuit at 86
Earth at 85

Fine with all that except...I have neutral switching on my car, so the wire that would usually go on 86 is already live (not just when main beams are on) which would mean spotlights are permanently on if I wired it this way. How do I wire-up the relay to take account of the neutral switching of the main beam circuit? I'm a heating engineer by profession, so be gentle. Thanks in advance (it's doing my head in!) Now left.
Post #671718 18th Dec 2017 4:07pm
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 4554

Click image to enlarge
Post #671726 18th Dec 2017 4:33pm
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Martin
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Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6683
United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Montalcino Red
Permanent live 30 and 86
Live out 87
Main beam trigger (Ground path) 85  1988 90 Td5 NAS soft top
2015 D90 XS SW
Post #671729 18th Dec 2017 4:42pm
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custom90



Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20916
United Kingdom 
If your trigger feed is earth, you'd need the other feed to be ignition switched live ideally.
(Or perm live.)
Reverse polarity basically. (But Relay coil is not polarity sensitive, so it doesn't matter which side.


85 - 86 the Relay coil can be engergised either way polarity is selected unless it's a with Diode type.

Normally it's the switched live that is the trigger feed, but you can use a neutral Earth switched feed instead.

30 is always the supply, and 87 supply out..

Make sure any permanent live if present is appropriately fused nearest power source as possible for safety sake.
(You probably know all this anyway...)
Thumbs Up ____\We|Will|Win/___
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Post #671734 18th Dec 2017 4:57pm
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Vogler



Member Since: 02 Nov 2014
Location: Brussels
Posts: 309
Belgium 2015 Defender 110 Td5 HT Chawton White
The setup in dorsetsmith's image uses a switched earth because it is necessary for that specific switch to work as it should with respect to the indicator light.

Joris
Post #671802 18th Dec 2017 7:47pm
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What puddle?



Member Since: 25 Oct 2013
Location: Reading
Posts: 952
United Kingdom 
Thanks to all - very much. I'm 99% sure I've got it - the 1% is I still don't understand why a live drops to an earth. But the important thing is:

Permanent live from battery at 30
Permanent live from battery at 86
Live out to spots at 87
Present live feed to main beam to act as trigger at 85

That right? Now left.
Post #671855 18th Dec 2017 9:49pm
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Martin
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Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6683
United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Montalcino Red
Bit confused, is your main beam trigger feed live (12V) or ground (0V) switched. You've said both now Wink  1988 90 Td5 NAS soft top
2015 D90 XS SW
Post #671905 18th Dec 2017 10:47pm
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What puddle?



Member Since: 25 Oct 2013
Location: Reading
Posts: 952
United Kingdom 
Well that's just it! The three-pin switch to the lamp fitting has all three female pins live - with the ignition off. So there's a permanent live to the lamp. Apparently (haven't yet tested this) when you put the main-beam stalk on, the corresponding female pin drops to 0 volts. This is what I just don't get.

As I understand it, the normal wiring for a relay is as described in my first post:
Permanent live from battery at 30
Live out to spotlights at 87
Live in from main beam circuit at 86
Earth at 85

But that's for positive switching. Whereas my car has negative switching. Now left.
Post #671914 18th Dec 2017 11:00pm
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custom90



Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20916
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All you'd do with the above is use the switched Earth on 85.
It'll only work however when the main beam is triggered also at the same time. ____\We|Will|Win/___
____/πŸ‡¬πŸ‡§πŸ‡ΊπŸ‡Έ\____
_//*β›½οΈπŸ›’οΈβš™οΈπŸ§°*\\_
Post #671928 19th Dec 2017 1:28am
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What puddle?



Member Since: 25 Oct 2013
Location: Reading
Posts: 952
United Kingdom 
So Steve, is this right, then, for negatively switching headlights - to bring the spots on when the mainbeams are on:

Permanent live from battery at 30
Permanent live from battery at 86
Live out to spots at 87
Present live feed to main beam to act as trigger at 85

I was confused, then a little confused, now back to confused again. Now left.
Post #671942 19th Dec 2017 9:12am
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 4554
ex GPO ,BT land rover Question pos grounded
Post #671950 19th Dec 2017 9:48am
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What puddle?



Member Since: 25 Oct 2013
Location: Reading
Posts: 952
United Kingdom 
Suzuki Jimny


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Those crazy Japs. Now left.
Post #671952 19th Dec 2017 10:23am
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 4554
Rolling Eyes
Post #671955 19th Dec 2017 10:32am
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What puddle?



Member Since: 25 Oct 2013
Location: Reading
Posts: 952
United Kingdom 
Yeah, but I'm putting a Defender grille on it! Now left.
Post #671959 19th Dec 2017 10:53am
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custom90



Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20916
United Kingdom 
What puddle - Before you touch the main beam circuits, make sure you test for voltage for polarity.
And do this on everything you do to be sure. (Reading back, I think you've done this)

Do you actually need the switch at all?
Because I have my spots main beam triggered and no switch and like it that way, okay you can't isolate headlight main beam from spots being on but it's a lot more simple.

Then you have the tell tale light to sort out with the switch as well.

If your using the main beam as your switching, basically all your switch is doing is being an isolator.
Because it's not a two way switch, you cannot have it: perm on/off/on with main beam.

It'll either do only: perm on/Off
Or On with main beam trigger/off. ____\We|Will|Win/___
____/πŸ‡¬πŸ‡§πŸ‡ΊπŸ‡Έ\____
_//*β›½οΈπŸ›’οΈβš™οΈπŸ§°*\\_
Post #671983 19th Dec 2017 12:54pm
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