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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

United Kingdom 
Fog Light Relay Operation
Hello folks,

Does anybody know how the standard fog light relay works? What the four pins are connected to? It's clearly some sort of latching relay and I have half an idea to re-purpose one.


Click image to enlarge

Despite all of the various numbers on it, the LR part no. is YWC104430.

Thanks for looking. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia


Last edited by LandRoverAnorak on 20th Apr 2020 7:48pm. Edited 1 time in total
Post #723300 13th Aug 2018 8:36pm
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sloderby1



Member Since: 08 Feb 2018
Location: Derby
Posts: 20


You're correct, its a relay with latching electronics.
Relay is latched if headlights are on & momentary switch is pressed.
Relay is released if:
a) momentary switch is pressed again.
b) headlights extinguished.

Connections:
A = +ve power from headlights
B = Batt -ve
C = +ve switched to fog lamp(s)
D = Momentary fog switch (normally open contact, switch to Batt-ve to operate)

Mating connector is Sumitomo type HMDC N-04F
Post #723327 13th Aug 2018 9:35pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

United Kingdom 
Ah, fantastic! That is just what I need.

That's another little project lined up, then. Many thanks. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia
Post #723331 13th Aug 2018 9:54pm
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diesel_jim



Member Since: 13 Oct 2008
Location: hiding
Posts: 6092

United Kingdom 2006 Defender 110 Td5 SW Epsom Green
I'm considering one of these for my heated screen wiring... my timer unit has gone duff (about 6 yers ago!) and getting one (a proper LR one) is quite costly... and I've got a spare fog light unit in the garage...
Post #723352 14th Aug 2018 5:56am
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

United Kingdom 
Me too. Bought on a whim as I knew it was a latching relay but didn't know how it was connected. Now though, I can use it to solve a problem described in my build thread. There I've used a different relay that's turned out to be too sensitive to be used reliably with standard LR buttons. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia


Last edited by LandRoverAnorak on 14th Aug 2018 8:14am. Edited 1 time in total
Post #723356 14th Aug 2018 6:13am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17387

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
diesel_jim wrote:
I'm considering one of these for my heated screen wiring... my timer unit has gone duff (about 6 yers ago!) and getting one (a proper LR one) is quite costly... and I've got a spare fog light unit in the garage...


Other, non-LR , options are available, for example https://www.12voltplanet.co.uk/adjustable-...v-10a.html

Still not cheap though.
Post #723371 14th Aug 2018 8:06am
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zsd-puma



Member Since: 09 Aug 2016
Location: Kent
Posts: 2720

United Kingdom 2010 Defender 110 Puma 2.4 USW Santorini Black
diesel_jim wrote:
I'm considering one of these for my heated screen wiring... my timer unit has gone duff (about 6 yers ago!) and getting one (a proper LR one) is quite costly... and I've got a spare fog light unit in the garage...


The front screen timer is originally from an Range Rover classic, so you can probably find a second hand one. Personally I'd go the original route rather than a bodge which will slightly devalue the car.

For anyone now reading this thinking they'll buy a fog lamp unit instead of a screen timer....
PRC6796 Front screen timer is £57,
YWC104430L rear fog lamp relay is still £45

If you don't have one sitting in the garage is it worth the hassle for the sake of £12?
Post #723405 14th Aug 2018 10:39am
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sloderby1



Member Since: 08 Feb 2018
Location: Derby
Posts: 20

Be careful of the current you're trying to switch.
The fog lamp relay is designed for 2 or 3 bulbs of 21W + indication at 1.4W so in the order of 5 Amps max.
This is confirmed by the design information for this device which states that it should be protected by a 7.5A fuse.

Internally the PCB tracks will be destroyed if the load is too great.
Post #723460 14th Aug 2018 4:52pm
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PaulMc



Member Since: 17 Jan 2009
Location: Kent
Posts: 501

United Kingdom 1989 Defender 110 2.5 TD HT Arles Blue
sloderby1 - Do you work at Pektron Question Paul.
1989 Arles Blue 2.5TD 110 Hardtop
1999 Epsom Green Discovery II 4.0 V8i 'XS'
Post #723463 14th Aug 2018 5:01pm
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MK



Member Since: 28 Aug 2008
Location: Santiago
Posts: 2416

Chile 2007 Defender 110 Puma 2.4 SW Chawton White
Dumb question

Why this thing is called ECU-one touch fog lamp? Do all Puma Defenders come with it?



Click image to enlarge
 Puma 110" SW

.............................................................
Earth first. Other planets later
Post #962243 19th Aug 2022 1:10pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

United Kingdom 
It's an electronic box of tricks that controls the fog light and yes, all Pumas (and '02 onwards TD5's) come with it. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia
Post #962251 19th Aug 2022 2:29pm
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Martin
Site Admin


Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6605

United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Montalcino Red
It turns a momentary ground signal from the fog push switch on 2002MY+ Defenders into a latched fog light output. The supply is from the headlight feed, so fogs only come on with headlights.

It basically stops the fog light being left on when the Defender is switched off and back on again.

Previous Defenders had a latching toggle switch on the steering column, and it can of course be left 'on'.  1988 90 Td5 NAS soft top
2015 D90 XS SW
Post #962254 19th Aug 2022 3:09pm
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macfrank



Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1076

Germany 2015 Defender 110 Puma 2.2 SW Keswick Green
When I first saw it I laughed at the term ‚ECU‘. Yes it‘s an Electronic Unit and it Controls something, but it‘s so simple, in modern card it‘s ‚one line of code‘ in the body/comfort ECU 🙃
Post #962266 19th Aug 2022 3:55pm
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