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Making my own main loom/harness


monkie

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Well this was a project I set myself for 2019 - oh well

Ever since I've had my 110, its had a common issue of unreliable electrics. Over the years previous owners and myself have made tempory repairs and addtions that have subsequently added their own problems. A big source of my problems is poor connections and old wires at the fuse box. I want to add in some modifications such as provision for a glowplug timer relay, headlights running from relays not the switch, intermittent wiper relay. I've bit the bullet - I have removed the main harness and intend to make my own as well as the harness that goes to the rear. I will be using the correct wiring colours to help me and also for any future fault finding.

I'm after some advice and tips from those who have done this before please: I don't like the bullet connectors and I also can't source some connectors such as those which go to the instrument panel.

  • What connectors do you recommend? (I like the look of the superseal type - any good?)
  • I was thinking of soldering the connectors in place - is this the correct method?
  • Any one have any diagrams (beyond the wiring diagram) that may help me?

 

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I got a new dash/main harness from Autosparks, it has the correct moulded rubber connectors, it was easy to fit & virtually plug & play.

if you want tomake your own they can supply the correctly rated & colour coded wiring but you will have to use different connectors as the moulded rubber type are not supplied seperatly, I think that would almost work out as costly as a ready made loom. 

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Thanks Ralph. I do use Autosparks. I did look at their off the shelf harnesses. Its almost £600 for a main loom plus anohter £90 for the chassis loom. I was hoping to come in considerably cheaper making my own! I am currently pricing up the shopping list to see how naive that thought might be!

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This is one of my projects as well. I'd recomend AMP Superseal as connectors if there is no need to stay original. They are best for sure.

On the other hand Autosparks provides a lot and this will save a lot of work. The bullet connectors will not be to bad, if you soak the cable ends and the connectors in hot vaseline. If the cable ends are soaked full of vaseline, the cables can't soak water with capillary forces. The cables won't get black so fast inside the isolation.

 

Edited by Sigi_H
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I have to admit I am a fan of the bullet connector - they are really easy to make, pretty flexible i.e. you can do quite a lot with it - very simple maintenance and as Sigi_H outlines there are a few steps you can take to improve the connection and make it pretty hardy to most elements it can be exposed to in a Landy.

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1 hour ago, Maverik said:

I have to admit I am a fan of the bullet connector - they are really easy to make, pretty flexible i.e. you can do quite a lot with it - very simple maintenance and as Sigi_H outlines there are a few steps you can take to improve the connection and make it pretty hardy to most elements it can be exposed to in a Landy.

Compare them to the likes of a Superseal or Deutsch connector and the bullet types soon fall way behind. Particularly in a harsh environment. 

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Just got all the stuff from Autosparks to make the Chassis loom whilst I figure out the main loom. A bunch of econoseal connectors, all the wires of correct colour code and rating plus tapes came to £45 - a huge improvement over the £102 off the shelf price.

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Been there, done this twice - 2 vehicles.

Use Superseal/econseal. Use the standard factory wire colours, work from the manual wiring diagram. Provide earth returns to each "appliance". These can be commoned up at left/right/front/rear corners. This is much more reliable than using body/chassis earths and cuts down corrosion.

 

Work in simple steps - chassis loom to offside rear, then loom across to nearside rear and trailer socket. Front wing looms, left and right. Left can include heater and washer pumps and horn. Internal dash loom for wiper etc. Engine bay loom.

Sheath each part in proper pvc flexible tubing. Pull a draw string through first and then pull loom through.

Get a proper crimp tool for the terminal connections. Solder them after crimping for double insurance.

Buy plenty of wire over and above what you need. Don't fit connectors until loom is all in place and fixed neatly.

Vehicle Wiring products have everything you will need. They show the cable sizes you need. Nothing much on a landy draws more than 10a except the start/charge wiring, although its worth going up a wire size for the headlights - makes them brighter. If you are feeling brave, convert to relay switching for the headlights - plenty of posts on here on how to do that.

Edited by simonb
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Thank you for this. I do have a proper crimp tool plus automatic wire stripper tool. I will solder following the crimping. 

I like the standard look so I have the proper tape and pvc sheath from autosparks. 

I am going to build in the glow plug timer relay as well as run the headlights off of relays. I have seen the how to posts on here. 

I can't source the terminals for the dash warning lights but if autosparks make the ready to go looms they must have them. I will give them a ring tomorrow. 

@simonbplease can you detail what you mean about the earths? Do you return back to a main bus to the negative battery terminal? 

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Yes run a heavy gauge 30a (can't remember the wire gauge but it will be in VWP, its only about 3mm in diameter) or so earth cable in your chassis loom, then branch that off to both sides at the rear. All of your individual lights on each corner and things like rear wiper/heated window if you have them, can connect to those earth wires. The single earth will easily take all of that load.

Do the same for each front wing - one earth per wing. Headlight/sides/indicators in each wing can share the same earth. I then added a 2nd earth wire in the left wing for heater fan, washer pumps and horn - so three branches off it. 

Connect all of these earths direct to the battery negative terminal - or the main earth stud on the transfer box, which should also have an earth strap to the chassis and another earth cable (of at least the same size as the battery positive lead) back to the battery negative. I found it was easier using the gearbox earth stud as the main earth, rather than trying to get it all on the battery negative terminal itself.

If you follow this approach, your electrics will never fail you again. Use superseal type connectors even internally such as for the rear light connections - much better than bullet connectors or 6mm male/female blade terminals. 

I reused the ignition switch/instrument loom as mine was unmolested and in good nick, if yours has been butchered/messed about with, then you may need to repair or replace. Personally I would repair bad sections splicing in new wires of the correct colour code, with soldered and heatshrunk joints. That will save you a lot of faff...

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I shall be doing this over christmas on the project chassis and engine looms already done ,but the main will be modded slightly . I'm using a disco 1 engine bay fuse box to distribute the power from the battery and after seeing Fridgefreezer's post I've got a maypole trailer wiring box at the rear to cut down on connectors , all wires connect with spade connectors inside . I also used bus bars at the front on each wing to connect the earth's too then a main earth back to the battery .

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@simonb thank you for this. My plans were to use superseal/econoseal connectors to replace all bullets for lights, where the main loom joins the chassis loom and engine loom etc and also for the earths. I was considering the same approach for the earth's you describe as I think the land rover way is terrible. Thank you for confirming.

My main issue is a messed about with fuse box with loose and damage wires (I'm worried about the fire risk), bodged chassis loom from previous owners, broken/worn connectors for the lights front and rear, plus land rover earth's! 

I think your idea is a good one to save time and money... To renew what I describe above but keep the instrument wiring as is and just build the rest of the loom around it. 

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The fuse block can be purchased new as can the terminals inside it. VWP don't do it, but I did find it online a few years back. I can't remember where, but try Google and look for images, it wasn't expensive.

Alternatively get a good used one from a breaker. I used that approach on my series 3, so it has a Defender fuse box with blade fuses to replace the original 4 glass fuses. You can then join your new loom to the cut off wires by soldering and heatshrink.

Most of the external wiring won't be worth keeping, water gets in and the copper turns black. Just replace all of that. Engine looms are normally ok, but check the insulation hasn't gone brittle. With a bit of luck, even bodged dash wiring can be repaired. The dash loom is the most complicated bit and has lots of common points in it. On both my series 3 and Defender, I picked the dash looms apart and rebuilt/modified them to my spec. Probably not recommended for the beginner!

Edited by simonb
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IMO it's really not a good idea to be soldering after you've crimped. All the solder is going to do is add a point at which the wire is more likely to fracture as the solder doesn't bend. If you're using a decent crimper of the right type (its about £30 for the Durite one for Superseal/Econoseal terminals), then soldering will make the joint worse mechanically. One common arguement is that it seals it... with the aforementioned connectors, the whole thing is sealed anyway so its rendered pointless. As for doing stuff like battery cables, just use a short bit of glue lined heat shrink over the back of the lug and that will stop any moisture getting in. Talking of moisture.... make sure any joins you do make are sealed, I ended up rewiring the rear of my 90 for its MOT sometime in the last century and the loom needed cutting back level with the drivers seat to get back to clean copper core! The join was behind a rear light. It had been soldered up and a bit of non glued heatshrink put over it.

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