D90 wiring loom - to replace or not

[muzaz]

I need some thoughts before I do anything to the wiring especially since I have no experience in the matter!

I have removed the bulkhead loom from my D90 in preparation for a bulkhead replacement. The wiring looks a bit stiff and brittle, it's an 1988 truck, and still has glass fuses in it. The connector plugs are super hard to separate. The wiring which goes into the gauges looks like a spaghetti dish! I would like to tidy up the harness, maybe use some conduit or some sort of seathing.

I also need to replace the engine loom, the original was for 2.5na and the replacement is 200tdi, but it has no wiring.

While at it, what are my options? Is it advisable to replace the loom with something more modern or use maybe use the original loom and make some changes etc? 

[Chicken Drumstick]

When you say “more modern” what are you expecting? In reality a new loom will just be wires and connectors. Apart from being less old it won’t be doing anything any different or more modern. 
 

Ie There hasn’t really been a technical advancement in wires. 
 

That said, if the old loom is at the point of cracked insulation and maybe poor connections. It may be worth replacing. Although it is not cheap or a 5 min job. 
 

Many people also upgrade the fuse box to the latter push in fuses. The glass style can be fine, but more prone to minor surface corrosion on the fuses that can cause issues. 
 

Making the loom look tidier might be hard. Wires need to go where wires need to go. And most are hidden away behind the dash. 
 

However, the old adage if it ain’t broke…..

As a rule many factory components are good quality and last well. And while we’d all hope buying new would be an upgrade, sometimes they don’t last as long. Not saying this will be the case, but cheap wires are rubbish and cause problems. Not saying any of the looms for sale are like this. But only time can tell. Many factory looms are still working perfectly fine in much older Land Rovers without issues. 

[Snagger]

The 200Tdi and 12J engine wiring is the same, except for some versions of the Tdi having the temperature sender in the thermostat housing instead of between some aft head bolts - that’d be easy to extend.

It does sound like a new loom may be due.  Once they go brittle, the probability of breaks and shorts goes through the roof, so from a safety as well as a reliability perspective, at least replacing the brittle and damaged parts is prudent.  Whether you build your own or buy one outright is a choice that depends a bit on cost and a bit on how standard you want the new loom.  I think some of the manufacturers are reasonably flexible, though

[daveturnbull]

If you go new, get a 200tdi spec loom. You'll get blade fuses and the connectors to all your column switches and other looms will be the same. And it will have the bonus of an extra wire for intermittent wipers.

[muzaz]

1 hour ago, Chicken Drumstick said:

When you say “more modern” what are you expecting? In reality a new loom will just be wires and connectors. Apart from being less old it won’t be doing anything any different or more modern. 

What I meant is, if I have to replace, do I replace like for like, ie 2.5na 1988 type, or go to a later type considering I am replacing the engine to 200tdi and bulkhead is a new 300tdi model. I don't know, maybe a later type loom has the connectors or plugs which are better, Dave mentioned the glass fuse box, etc. 

The thing is once the loom is out, if I should do something to it, now is the time. I wouldn't have dared to touch it if I didn't have to replace the bulkhead!

Taking a closer look at the loom, it does not look cracked or chaffed in anyway, just a bit stiff. Not sure if it is still in the original state as there seem to be some additional wires and splicing, mostly related to the radio I think. Will delete those for sure.

 

[Snagger]

I suspect that letting it sit in a bucket of oil for a week or more would soften the insulation again and could help clean some of the contacts, but if you find brittleness and much corrosion of wire or terminals, then replacement is perhaps best.  Without seeing in the flesh, I can’t be confident it needs replacing, and you can certainly replace the fuse boxes with later if you are happy to splice it in.  The engine loom mods are minimal and simple and certainly don’t demand a new loom.  I doubt the addition of the intermittent wiper wire or the later fuse box make it worthwhile either.  I’d only replace it if you have concerns over the condition, not the spec, of the existing loom.

[FridgeFreezer]

You can swap in blade fuse boxes easily to that loom:

https://fuddymuckers.co.uk/wiki/doku.php?id=alfie:fusebox_upgrade

 

See also the added "main fuse" mod I did on that page too, although a single ~50A MIDI fuse would also work.

 

Worth saying any loom you buy is going to be a mess behind the dash as that's just how it always ends up, I've built my own from scratch several times and it's damn near impossible to get it all neat back there in the available space with the way the gauges are mounted etc. unless you have the patience of a saint.

[bishbosh]

With the bulkhead out it is an obvious time to change the loom for peace of mind but it is not cheap. So to me the quesiton to ask yourself is, "Am I confident diagnosing and fixing electrical faults in an old loom". I fthe answer to that is "No" then it may be worth considering replacing the whole lot which may not eliminate the risk of a future electrical gremlin, but it should significantly reduce it.

[steve b]

Whether you keep the original or go to a new 200Tdi spec there are two things I would add to re-installation

1. Good earth return wiring that goes either to the engine block or direct to the battery -ve. This would include rear lighting, both front wing earth points and the dash/bulkhead earth point. 

2. Relays for dip and main beam to take the load off the switch

Steve

[muzaz]

There were some electrical issues before I took the loom off...hazard lights did not work, exterior lights did play a bit, but most probably that's from the stalk switches, wipers - rear did not work, the front worked but did not park, they stopped when you switched them! Dash gauges light needed a tap to turn on etc.

So apart from the loom, there are other things such as the indicators and lighting stalk switches which I will replace.

3 hours ago, FridgeFreezer said:

You can swap in blade fuse boxes easily to that loom:

https://fuddymuckers.co.uk/wiki/doku.php?id=alfie:fusebox_upgrade

See also the added "main fuse" mod I did on that page too, although a single ~50A MIDI fuse would also work.

Thanks for that @FridgeFreezer good write up and something I could follow. Must do something to make it neater tho, the fact that I have to push on the instruments binnicle to keep the wires makes me...🥺

2 hours ago, steve b said:

Whether you keep the original or go to a new 200Tdi spec there are two things I would add to re-installation

1. Good earth return wiring that goes either to the engine block or direct to the battery -ve. This would include rear lighting, both front wing earth points and the dash/bulkhead earth point. 

2. Relays for dip and main beam to take the load off the switch

Steve

Thanks @steve b, I'd like to add relays because I think that's one of my current problems. Will have to do some research on how to add the relays tho, as I said earlier, I'm quite useless when it comes to electrics 🙄

[muzaz]

After finding the price (1k) for a new loom 😳 I think I will keep mine.

I damaged some of the bullet connectors during removal and can't find similar replacement, and anyway I don't like them, too difficult to separate, so I'm thinking of replacing them. 

I found these connectors called Deutsch DT and they look quite good, waterproof etc. Any experience or better solutions?

https://www.te.com/en/products/connectors/automotive-connectors/intersection/deutsch-dt-series-connectors.html

 

[Eightpot]

If it were mine, I'd unwrap the loom, repair/replace any damaged wires, replace the lighting bullet connectors with 300tdi style connectors so you can use the later lamps, and give the fuse box a good clean up with white vinegar or something to get the corrosion off.   

You can easily buy the correct coloured wire if you need to replace any sections, buy all new lucar connectors where necessary and re-wrap it nicely.   I have plenty of problems with my 200tdi fuse box, they aren't immune to corrosion problems -  neither are the later looms (had plenty of fun chasing electrical faults inside header joints).

[FridgeFreezer]

14 hours ago, muzaz said:

I found these connectors called Deutsch DT and they look quite good, waterproof etc. Any experience or better solutions?

TE are one of the BIG manufacturers and I'd certainly trust anything they made to be up to the job.

I used a lot of AMP Econoseal in the 109 mainly because the 300TDi lights use them so I bought a party pack of them, they are another popular one from a big name (in fact these days TE own them I think) that are used as OEM on cars & trucks etc. so no worries about using them.

I try to buy from suppliers who sell the genuine stuff not chinese copies.