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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202   
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Hello,
I've just fitted one of the 3 pole heated windscreens (2+ and 1-) and was wondering about the pros and cons of either wiring it to the main battery or my leisure battery. Both batteries are sited next to each other and due to the power hungry nature of these twin circuit windscreens I'm tempted to go for the leisure battery. The dash switch will energise a 10 min timer relay which will energise a pair of 30A power relays. Any pros/cons of pitfalls..?? Cheers, Dave 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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12th Mar 2023 2:50pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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...and one for the electrical gurus - 10 minute timer relay to energise a pair of 30A power relays (one for each positive on my winscreen) or timer relay to energise a single 70A power relay then split the feed from that to both +'s..??
Cheers, 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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12th Mar 2023 3:16pm |
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| macfrank Member Since: 05 Nov 2015 Location: somewhere in the north Posts: 1081  
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double post
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12th Mar 2023 7:33pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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Thanks macfrank - any idea where I could find an 'engine running feed' in the dash area..??I
I could find a couple of switched positives - no problem - but engine running..?? Cheers, Dave. 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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12th Mar 2023 8:04pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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Could it be that using the Leisure battery would negate the need/worry of taking too much juice out of the starter battery..?? 2002 Land Rover 110 Td5 Utility
1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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12th Mar 2023 8:06pm |
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| Penfold_6290 Member Since: 22 Sep 2021 Location: Dorset Posts: 320 
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To be clear, on a Td5 the ‘engine running’ signal for the OEM HFS system is from the oil pressure switch in the engine, no oil pressure, no HFS. The oil pressure signal goes direct to the HFS timer. It does not come from the instrument cluster. Depends on how diligent you are as to whether you need to go to this extent.
My home wired HFS uses the genuine in dash switch that has the internal track modified (there will be a thread in here somewhere of how to do it) which triggers a timer which powers a relay, just like you suggested in your original post. I sited the relay and the fuse under the drivers seat. Your choice of whether you use two relays or one big one. You’ll either have to split the incoming 12v into two if you use two relays or the switched 12v output will have to be split into two if you use one big relay. |
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12th Mar 2023 8:20pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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That's excellent into - thank you.
I've bought a genuine switch for the dash - wiring that'll be my next headache (I'm very 'mechanical' biased - I have a multimeter but have no idea what most of the settings do - just 'volts' and 'continuity') 😄 I'll try and find your thread - it sounds like I need to read it... Thanks again. 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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12th Mar 2023 9:26pm |
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| Penfold_6290 Member Since: 22 Sep 2021 Location: Dorset Posts: 320
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From memory the OEM HFS switch is a non latching type that creates a route to earth rather than a 12v output. You can cut one of the tracks inside the switch so that it creates a 12v output instead, which suits most timer relays because they only require a momentary 12v signal to start the timer rather than a constant 12v supply.
PaulMc is a member here and he knows more than there is to know about these switches. You could search his posts or send him a PM |
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12th Mar 2023 9:53pm |
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| Penfold_6290 Member Since: 22 Sep 2021 Location: Dorset Posts: 320
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To be fair volts and continuity testing is about all you really need for general LR wiring jobs. What I know is when you've modified the internal track on the genuine switch (I can take a pic of you can't get hold of Paul) you will need a 12v live into the switch, an earth, a connection to the red/orange wires from adjacent switches for night time illumination and finally from the switched live from the HFS relay so the tell-take light illuminates when there is an output from the relay to the screen. Here's how I wired mine in, including which terminal each wire goes to in the modified switch. Remember - this will only work if you have correctly modified the switch. If you try this without modifying the switch your windscreen will be demisted by the resultant fire in the dash board!!! 
GW is an ignition live RO is switch illumination KO is the momentary 12v output when the switch is pressed PS is the 12v output from the relay to the switch tell-tale light PY is the timed 12v output from the timer N 6.0 is a heavy guage wire carrying the load current to the relay and to the screen. Any black arrow is an earth  Click image to enlarge Last edited by Penfold_6290 on 12th Mar 2023 10:18pm. Edited 1 time in total |
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12th Mar 2023 10:14pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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Superb - thanks a lot. I shall search for his posts...
You're absolutely correct in that the switch doesn't latch. A bit like my brain which isn't latching with wiring this thing up...😄😄 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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12th Mar 2023 10:17pm |
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| Penfold_6290 Member Since: 22 Sep 2021 Location: Dorset Posts: 320
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See the post above, that should help. I can take my switch apart and take a pic of the internal tracks but probably not until next weekend as I am in the Netherlands most of next week.
Paul Mc also has an Ebay shop where sells the correct plug for the back of the switch and crimp terminals. https://www.ebay.co.uk/sch/i.html?_trkparm...connectors You need the white one https://www.ebay.co.uk/itm/155390012860?ha...SwhfBj3CFF |
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12th Mar 2023 10:19pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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The above posts are very helpful - thank you very much.
I've ordered the plug (white one) and will send Paul a pm asking if he can tell me how to wire the connector. I searched the forum last night for posts from PaulMc (and yourself) but I ended up scanning down the page and thinking "Ooo, that sounds interesting - I'll read that..." and going off on tangents 😄 Enjoy the Netherlands - it's one of our favourite countries. We regularly used to visit the North - Assen\Groningen area. Cheers, Dave 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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13th Mar 2023 10:06am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17443 
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It's only on the TDCi that there is an "engine running" output on the IPAC connector. I'm not sure how the IPAC determines that the engine is running, it will be CANbus dialogue between the ECM and IPAC of some sort. |
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13th Mar 2023 12:51pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 202
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Thanks blackwolf....
Things like 'CANbus' are what terrified me about my Freelander 2. I'm beginning to think that I should have got a 200Tdi instead of this Td5...🤔.... 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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13th Mar 2023 1:01pm |
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