Troll Hunter Posted March 3, 2021 Share Posted March 3, 2021 It's a 1991 110CSW originally V8but now 300Tdi. Having stripped it down, galvanised the chassis, bulkhead and lots of smaller bits, I'm now trying to do a rewire job as I rebuild the bodywork. Looking at the original loom it looks very much as if LR used a common loom for whatever vehicle they were building and just ignored the wires they didn't need for that model. All over the original loom there are wires with terminals that never connected to anything just taped into the loom. My immediate problem is the row of relays beneath the fuses in the fuse panel below the dash. Excluding the indicator relay and the intermittent wiper relay, in my installation there are eight relays, the two on the left have green bodies, and the remainder all have yellow bodies. I don't think the colour affects the electrical properties! The loom itself is so complex and cumbersome, although I've stripped nearly all of the binding tape off, it's almost impossible to follow individual wires back to the relays, so can anybody tell me what each of these eight relays serves, please? I'm very inclined to just dump the entire loom, save the fuse panel and relays, and start totally from scratch. I'll certainly be using some decent connectors on the new loom, and I'll include only a couple of spare conductors for future use. I've been avidly following Monkie's thread "Making my own main loom/harness" and have picked up many good points there, but no identification of these relays. Many thanks, in advance, to anyone who can identify these relays. Mike Quote Link to comment Share on other sites More sharing options...
monkie Posted March 3, 2021 Share Posted March 3, 2021 Great to hear you're giving it a go. To be honest it's taking me longer than I thought but I'm trying to do it around work and family commitments. You're right about the generic loom, there is loads of stuff that will be unused or spare. You need to take loads of photos and make diagrams and notes. Get yourself totally familiar with the wiring colour codes and then you can work most of it out for yourself. I think the biggest improvement I think I've built in is a nice thick earth wire to each corner which go to bus bar in the battery box. Hopefully no more earth faults... Ever! This Linky will help you in terms of relays. Good luck! Quote Link to comment Share on other sites More sharing options...
Maverik Posted March 3, 2021 Share Posted March 3, 2021 Something I saw while out and about. - getting your loom lengths correct to each of the locations. So one of these defender re-manufacturers - they build there own looms, they had a big board laid out in which all the locations within the vehicle are drawn - so it looks a bit like the old London tube map. requires a bit of space, but if I where to make my own loom, I'd get the old one, nail it all out to a big board and map out the different end termination locations - this would give you a really good starting point for getting all the lengths in the right place 2 Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted March 3, 2021 Share Posted March 3, 2021 I experienced the same and this is why i think about building a new loom with a mo.unit from motogadget I would strongly appreciate it, if somebody knows about a similar unit for cars. Quote Link to comment Share on other sites More sharing options...
western Posted March 3, 2021 Share Posted March 3, 2021 90 & 110 use a common loom with all the possible options that were available, that's the fastest/easiest way if your producing lots of vehicles with different options, otherwise there could/would be hundreds of different looms to cover all the possible configurations. Quote Link to comment Share on other sites More sharing options...
Adam001 Posted March 5, 2021 Share Posted March 5, 2021 Just a comment on the DIY approach. I did it and so glad i did, my harness is completely custom, the standard defender one has so many flaws and in many instances is woefully protected from a fuse standpoint, e.g. from memory on mine there was no fuse protection to the ignition barrel and the load the barrel took on crappy spade terminals was way over what it should be. Now my ignition barrel only takes around 5amps of current with a fuse. I've then had freedom to do the rest of the system as i've seen fit. Been there for 8 years now and not a single electrical issue. If you go that route you can do what you want and you just have to work out the small defender bits such as the steering column stalk switches, hazards etc but they are straightforward once you get there. So if you are willing to tackle it, have the skills and take the time over design and build, go for it Quote Link to comment Share on other sites More sharing options...
=jon= Posted March 5, 2021 Share Posted March 5, 2021 On 3/3/2021 at 1:13 PM, Sigi_H said: I experienced the same and this is why i think about building a new loom with a mo.unit from motogadget I would strongly appreciate it, if somebody knows about a similar unit for cars. That's really neat! I've not seen similar for cars, apart from the high end power distribution units used by motorsport builds: https://www.cartekmotorsport.com/power-distribution-modules/ But they are significantly more expensive than what you have linked... Quote Link to comment Share on other sites More sharing options...
=jon= Posted March 5, 2021 Share Posted March 5, 2021 Quick google refers back to here: There's a few other options listed on there... Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted March 5, 2021 Share Posted March 5, 2021 Just read it. Thank you Quote Link to comment Share on other sites More sharing options...
SteveG Posted March 5, 2021 Share Posted March 5, 2021 I’m fitting one of these to the RR... https://www.aimshop.com/pages/power-distribution PDM32 Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 6, 2021 Author Share Posted March 6, 2021 Many thanks for your encouragement, Adam001. I certainly don't have the skills or experience, but I do have the enthusiasm and time to try and do it right, perhaps not always the first time! I'm gaining many good tips from Monkie's build thread, but still finding tripwires (!) and am very much feeling my way. Mike Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 7, 2021 Author Share Posted March 7, 2021 Now I need some tuition, please. I've been studying the operation and wiring of the VSS (or VSR) connected to the HRW circuit. I'm no lecky, by any means, but I'm wondering how the alternator warning light works. The light goes off when the alternator charges the battery. Couldn't this circuit be used the same way as the VSS, but with a Normally Closed relay in it in series with the warning lamp? When the alternator is charging the warning light goes out and the NC relay makes contact, thus allowing the HRW to be heated, via of course, another relay. There, I've just proved I'm no lecky! So put me right, tell me where my thinking is way off, please. Mike Quote Link to comment Share on other sites More sharing options...
monkie Posted March 7, 2021 Share Posted March 7, 2021 Can I just clarify your TWAs so we know we are talking about the same thing: VSS voltage sensitive switch HRW heated rear window NC no charge I can't figure out why your method wouldn't work but I'm also not sure what you'd gain as you'd essentially be swapping a VSS for a relay. Quote Link to comment Share on other sites More sharing options...
ianmayco68 Posted March 7, 2021 Share Posted March 7, 2021 I’m just about to start the main loom for the 90 , I’m using a GLR10 timer relay triggering a main relay. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 7, 2021 Share Posted March 7, 2021 IIRC the x-eng split charge would pick up from the charge light wire on the back of the alternator, so you are only charging, or linking the second battery when the engine is charging. Other options are to use the oil pressure switch, so you know the engine is running. Quote Link to comment Share on other sites More sharing options...
Adam001 Posted March 7, 2021 Share Posted March 7, 2021 (edited) Best practice is to leave the alternator charge line to just do its purpose. I would use the oil pressure switch as bowie has said. On mine I have a 'engine run' circuit that provides a 12V supply only when the engine is running, i do that using 2 relays, one in NO and one in NC, to handle the oil pressure switch being NC. that circuit then serves everything where i need to know the engine state. also look at using a Nagares TLT/5-12 10min timer relay, for the window, they are pretty cheap and handy. Edited March 7, 2021 by Adam001 Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 7, 2021 Author Share Posted March 7, 2021 8 hours ago, monkie said: Can I just clarify your TWAs so we know we are talking about the same thing: VSS voltage sensitive switch HRW heated rear window NC no charge I can't figure out why your method wouldn't work but I'm also not sure what you'd gain as you'd essentially be swapping a VSS for a relay. VSS voltage sensitive switch - Yes HRW heated rear window - Yes NC no charge - Normally Closed Many thanks for your thoughts and comments. It seems that I'm not totally out to lunch. I was hoping to gain simplicity and perhaps better reliability. Looking through the various threads about VSS on this forum, from 2008 through to 2018, it appears that they are not all that reliable, possibly needing some internal adjustment/calibration, and they are very expensive to replace. A simple relay is cheap and can be replaced without selling body parts. I agree that I could also use the oil pressure warning light as an initiator. ATM I'm considering using that to link to the FIP shut-off solenoid so that the engine will crank and build oil pressure before fuel is admitted, and it fires. I tested this set-up manually before I started my renovation project and it seemed to work well. It does need a well charged battery though. I'd be interested in other peeps thoughts on this. Mike Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 7, 2021 Share Posted March 7, 2021 For split-charge I just used an intelligent relay which is a ~150A relay with a VSS/timer built in, it waits for the battery voltage to come up before engaging the relay. Simple and cheap. All this malarkey about linking oil pressure switches and whatnot feels like overkill and added complexity to me, manufacturers don't bother with it even now when it would cost them literally nothing as it's all done in the ECU software, unless you're in the habit of starting your engine and immediately red-lining it I doubt very much a couple of extra turns of the crank are going to make the difference. Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted March 8, 2021 Share Posted March 8, 2021 I just used the light voltage for switching split-charge. When the light is switched on a strong relay connects both batteries. For ca 30 sec you may have a big current and then its ok. Since I drive always with light charging is normal and while standing the batteries are separated. Quote Link to comment Share on other sites More sharing options...
Snagger Posted March 8, 2021 Share Posted March 8, 2021 4 minutes ago, Sigi_H said: I just used the light voltage for switching split-charge. When the light is switched on a strong relay connects both batteries. For ca 30 sec you may have a big current and then its ok. Since I drive always with light charging is normal and while standing the batteries are separated. I have something similar, a Durite Hd relay sold as a split charger, using the alternator diode pack terminal to the charge light to control the relay like you did. It works very well and has been 100% reliable. The only side effect has been that on initial start up of the Tdi, I need to give a small blip on the throttle to get the revs over around 1000rpm for just a moment (a second or less) to trigger the diodes and get the charge light out. With the relay disconnected, that little blip isn’t required. But once that is done, the light stays out (not even dim) at idle. Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted March 8, 2021 Share Posted March 8, 2021 The advantage of using the light is, that i can decide to connect or disconnect it. Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 8, 2021 Author Share Posted March 8, 2021 I still haven't had an answer, as far as I can tell, as to the method used to extinguish the charge warning light when it receives adequate voltage from the alternator. On the wiring diagram in the LR manual the only indication of something is the "Ignition light resistor" which appears to be in parallel with the "Charge warning light". How does this bit of the charging circuit work, please, and where should I look for it? I've found what I think is a second diode in my wiring loom, the first one being associated with the HRW. Is this diode in the charging circuit? Many thanks for any lessons delivered. Mike Quote Link to comment Share on other sites More sharing options...
western Posted March 8, 2021 Share Posted March 8, 2021 IIRC they prevent the charging current back feeding to alternator & VSS. all the VSS does is to stop battery drain when HRW is switched on with engine not running/alternator ot charging, therby preventing a flat battery if HRW is inadvertently left switched on. the charging circuit one is within the main/dash loom but I can't remember its exact location. Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 9, 2021 Author Share Posted March 9, 2021 Thanks, western, for confirming that the the second diode I've found is in the charging circuit. I wish that the LR technical writers would provide this sort of detail in the wiring diagrams. So, what is the purpose of the "Ignition light resistor" which appears to be in parallel with the "Charge warning light"? Does anybody know? Mike Quote Link to comment Share on other sites More sharing options...
western Posted March 9, 2021 Share Posted March 9, 2021 See Errols reply in here Quote Link to comment Share on other sites More sharing options...
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