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| dorsetsmith Member Since: 30 Oct 2011 Location: South West Posts: 4554  |
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18th Dec 2017 3:33pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6627  
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Permanent live 30 and 86
Live out 87 Main beam trigger (Ground path) 85 1988 90 Td5 NAS soft top
2015 D90 XS SW |
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18th Dec 2017 3:42pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20549
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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...)  KEEP CALM AND Drill ON
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18th Dec 2017 3:57pm |
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| Vogler Member Since: 02 Nov 2014 Location: Brussels Posts: 309  
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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 |
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18th Dec 2017 6:47pm |
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| What puddle? Member Since: 25 Oct 2013 Location: Reading Posts: 952
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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. |
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18th Dec 2017 8:49pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6627
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Bit confused, is your main beam trigger feed live (12V) or ground (0V) switched. You've said both now
 1988 90 Td5 NAS soft top
2015 D90 XS SW |
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18th Dec 2017 9:47pm |
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| What puddle? Member Since: 25 Oct 2013 Location: Reading Posts: 952
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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. |
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18th Dec 2017 10:00pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20549
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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. KEEP CALM AND Drill ON 🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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19th Dec 2017 12:28am |
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| What puddle? Member Since: 25 Oct 2013 Location: Reading Posts: 952
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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. |
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19th Dec 2017 8:12am |
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| dorsetsmith Member Since: 30 Oct 2011 Location: South West Posts: 4554 |
ex GPO ,BT land rover
 pos grounded |
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19th Dec 2017 8:48am |
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| What puddle? Member Since: 25 Oct 2013 Location: Reading Posts: 952
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Suzuki Jimny
Click image to enlarge Those crazy Japs. Now left. |
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19th Dec 2017 9:23am |
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| dorsetsmith Member Since: 30 Oct 2011 Location: South West Posts: 4554 |
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19th Dec 2017 9:32am |
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| What puddle? Member Since: 25 Oct 2013 Location: Reading Posts: 952
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Yeah, but I'm putting a Defender grille on it! Now left.
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19th Dec 2017 9:53am |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20549
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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. KEEP CALM AND Drill ON 🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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19th Dec 2017 11:54am |
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