Replacing The Main Wiring Loom (Part One)

I finally got round to fitting the replacement front loom I bought back in 2017! Though I've not wired anything up yet........

Replacing the loom was a matter of safety as much as anything. Being a 1968 car, my car unfortunately falls into a small window of time where the looms fitted to Ds were of poor quality and have not stood the test of time. They suffer the dreaded 'LOOM ROT'...............

Curse of a 1968 car - LOOM ROT......

I think it's found on cars from the model years 1967, 1968 and 1969. But it might be more. maybe 1970 too? It's something to do with the material used in the insulation - particularly on (only on?) the black wires. Unfortunately that's just about all of the wires under the bonnet!

Over time the insulation hardens and cracks.

It starts with hardening and a crack

If left undisturbed, it just about holds together, but the slightest movement or attempt to bend the wires results in the insulation flaking off. What is usually revealed is already tarnished copper wires. 

Tarnished and damaged wires

This means that they do not conduct as effectively.....

Hanging by a thread (or wire).......

....and may short-out - causing a fire. The looms are wrapped in cloth tape and over the years this fades and disintegrates, ending up looking like the bandages of an ancient Egyptian mummy. And that insulation rot extends within the wrapped loom.

Hidden within the loom

The rot really was everywhere. 

This rot may be heat related - as it seems to happen mostly to the wires under the bonnet - rather than behind the dashboard. But there were also signs behind the dash.

Cracked and missing insulation behind the dash - on a relay wire

A few rotted wires can be repaired. Initially I anticipated a wire-by-wire repair: unwrapping the loom, patching wires within and then re-wrapping. I vaguely remember doing some of that on my old ID19b. It was a 1969 car so had the same problem. 

However on rediscovering my DS car back in 2014, the damage was so chronic and acute that a more serious solution was needed. i remember being nervous about trying to start it in case it caught fire.  A few years ago I found myself with some Ds repair budget and splashed out for a loom. Luckily, replacement looms are offered for just about all the left hand drive Ds variants - and even a couple for US and right hand drive cars.

Clearly, the important thing was to order the correct loom. Unusually there were two different looms for 1968 model year cars.

Replacement looms are readily available

It wasn't too hard to work out what was needed though. The loom had a handy 'tell' to help me decide. The relays for the lights are behind the dash and can be seen with the ashtray out.  All the 1968 cars have a relay for the headlight flasher. But there was a change to the 1968 model year cars in December 1967. Before that date each of the Pallas 'QI' lamps (the swivelling ones) additionally had its own relay - so three relays behind the dash.

Before december 1967 - two QI relays - parts 27 and 28

After that date, a single relay was shared both QI lamps. So with the flasher relay, just two relays behind the dash.

From december 1967 - just one QI relay now - part 27

That's what mine had. 

Only two relays behind the dash

My loom also has earthing wires for the courtesy light switches - another December 1967 change.

Power AND earth lead to courtesy light switch on door post

AND my wiper motor had the extra earthing wire.

Grey earthing wire on the wiper motor

Everything tallied. All these things help to understand when my car was probably made - early 1968. That means that the loom for my car is the one in Operation DX.510-00C in manual 814. 

I removed my loom back in ?????? when I was cleaning the engine bay for painting.

Out with the old....

I ordered the replacement loom from Citroen Classics at the D rally some years ago. They are made to order in Germany and customers are advised of a long (3 month) lead-in time. That was fine by me as I had plenty of other things to do and wasn't planning on fitting the loom just yet.

When it arrived, the loom was a joy to see. With it came a photocopy showing which loom diagram it was - drawing 51-26 - which is the wiring layout for Operation DX.510-00C in manual 814. That's the one.

The majority of the wires have numbered sticky tags on them. Referring to the wiring diagram that came with the loom, these relate to the part number the wire fits to. The tags don't represent the wire number in the diagram. So for example a wire tagged '20' fits to the alternator. 

'20' identifies this wire as an alternator connection

It doesn't represent wire 20 - from the horn switch to the wing. I'm finding some of those little white tags have fallen off, but - based on the ones that haven't fallen off, the coloured 'tells' on the wire ends and the branching - I'm sure I'll work it out the connections when the time comes.

The new loom uses modern plastic coloured 'tells' on the wires rather than the plastic/ fabric ones on my old loom.

Original plastic and fabric 'tells'

There are ten different coloured 'tells' on the wire ends.

DS wire colour-coding

Different coloured 'tells' on connectors

All but one of those on the new loom are plastic. The mauve (pink) one is made of textured rubber for some reason?

'Mauve' (pink') tag is rubber

I assume that the loom manufacturer couldn't source plastic sleeving to represent violet AND mauve - so had to come up with a solution.

many years ago I bought a pack of 'tells' from the Citromobile in Holland. These included violet AND pale mauve (pink) plastic pieces. I'd love to buy some more - but can't find the supplier.

Another Holy Grail to find - mauve tags.....

So plastic and rubber they may be on this new loom, but I think they will hold their colour better than the old ones did and this loom is going to be far safer to use than my old one.

With the engine bay painted, fitting was a doddle once I'd worked out which bits were behind the dash and which branches needed to pass through which holes in the bulkhead. I laid out the new loom alongside the old to orientate it.

Old and new

And then began to lay it down and route it.

Loom secured by clips

Threading the loom through the bulkhead

The new looms come with some cheap-looking foam grommets for the bulkhead. They look like offcuts of pipe insulation.

Probably because they are? Instead, I salvaged my old rubber foam grommets from the old loom and re-used those. I bet i'm not the first to have done that.

New and old grommets

I think the old ones look better

The fuse holders slid and clipped into the original 'Gelbon' fuse holders nicely - which helps to keep more of an original look. Especially with the old foam rubber cable grommets.

And there are insulators on the alternator wires and for the voltage regulator.

The loom is nicely bound with cloth tape - again helping to give it an original look.

I'm sure it was the same with the original looms, but that binding stiffens the loom up a little and it took quite a bit of twisting and pushing to get the loom to lay where I wanted it to - particularly around the steering column area. Luckily there are various clips on the chassis to hold the loom where needed.

Loom passing over the steering column and through the bulkhead.

The loom included the correct, smaller 3mm connectors for the oil pressure switch and the courtesy light switches - which was reassuring.

In terms of quality control, the wires to the right hand wing are coming up a little short. Not so short that I won't be able to connect them, but short in terms of the wrapped part of the loom not sitting behind the loom clip. 

Coming up a bit short for the clip

That's a shame. I might yet extend those wires.....

The wiring for the two relays looks to have been swapped around too. On my original loom the flasher relay was on the right hand side. On the new loom, based on the number of wires and their lengths, the flasher relay needed to be on the left - so I swapped them around.

I had to swap the relays over so that the wires reached

It doesn't really matter. When I refit them, I may just label up the relays to remind me.

There are a few 'flying' (seperate) earth leads found behind the dash. They aren't part of that main loom, and so don't come with the replacement. 

Flying earths on the common earth terminal behind the dash 
NOT to be confused with the accessory terminal!

That means re-using the old earth leads or making new. Luckily the old ones aren't covered in black insulation so haven't rotted, and I will use those again.

I guess I will have to write-up a 'part two' to this when i fit the dash and switches. I might find a few other odd things when I wire the loom up and test it, but I'm very reassured and pleased with what i have found so far.