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MG Midget and Sprite Technical - Changing wiring loom

Hi, new to this forum but would be grateful for advice.

I'm planning to change the (dash and front) wiring loom later this week on my mk2 midget and have sourced a new one via MGOC. Having not done this before, I would be grateful for any tips. For example, I was hoping to leave the steering wheel and possibly even the dash in situ, but will this make it much harder than it needs to be?
Any tips gratefully received

Thanks, James
J Fettiplace

Hi James, and welcome.

Take photos, lots of them, before you disconnect anything. Include shots of the connection terminals on every switch, light, gauge etc and general ones of the layout and route of cables.

I would leave the dash in and reach up from below, using a good torch helps. Also remove the tachometer and use the mounting hole as an access to help reach in to the connections either side.

Do you have a copy of the relevant wiring diagram for your car? (Haynes, WSM,)
GuyW

I am afraid I would disagree with you Guy (first time ever!). I would undo the dash, it's only five bolts that are pretty easy to get to (well, it is on my 1500) then tilt it down and forwards.

It's an extra step but saves lots of time and difficulty rummaging behind the dash.

The rest of it should be pretty easy. Just match up the colours and connectors. It should be like doing up shirt buttons, the connectors should only really fit in one place!

The one place you need to take care is the ignition switch as there are quite a few terminals and wires there.

All the best. Don't be afraid of electrickery. It's pretty simple really :-)

Malc.

P.S. edit: you might need to remove column cowl and maybe column switch, but also easy.
Malcolm Le Chevalier

No problem with you having a different point of view Malcolm!
But James, I would add though, if undoing and removing, or tilting the dash to gain access to the wiring, be careful of the capillary tube to the temperature gauge. They do fracture quite easily if bent too much and they cannot then be easily repaired. It usually ends up with needing a complete replacement gauge.

(this isn't a risk with Malcolm's 1500 as the gauge is electric on that model)
GuyW

Mine is earlier 1500 that has the capillary. The issue I had though is I cut through it by accident not knowing what it was! :-D

I digress. As you were!
Malcolm Le Chevalier

Hi James, welcome.

I'd suggest leave in dash but remove the steering wheel as it's so easy to remove and it with give you more working room on the driver's side.

Here's John Twist's easy method of steering wheel removal -
http://www.youtube.com/watch?v=lwf2BDC5DMo

You'll also have a wiring diagram and lots more useful info in the Driver's Handbook -
http://www.mgocshop.co.uk/catalog/Online_Catalogue_Handbooks_5.html
Nigel Atkins

gday James I may have missed it in the posts but firstly disconnect the battery.
Cheers
R W Bowers

hi james
bob here who sold you the car. that wiring loom was replaced in 2012. you can phone me if you need to know anything.
bob
Bob Taylor

hi james
bob here who sold you the car. that wiring loom was replaced in 2012. you can phone me if you need to know anything.
bob
0:22^6:0:1^120:0:2^15:0:1^14:0:1

Depends whether you're young and flexible, James. I wouldn't like to lie on my back with my head held up awkwardly to see what I'm doing, and my legs over the rear deck, for too long. I think the torture would encourage me to rush the installation.

So it would be release and tilt back for me.
Nick and Cherry Scoop

some petroleum jelly on the connectors and they will never fail during your live.

Flip
Flip Brühl

Just completely rewired a frog.

I strongly suggest you make sure you understand how the loom relates to the car before you start. THere are a lot of cable ends and it is good to know what goes where on the kitchen table rather than upside down in the garage. Cross reference it to the wiring diagram.

I left the dash in situ but removed the steering wheel.

It may be useful to cut the old wires out leaving a tail on all the connections. That way, assuming it was a standard loom previously fitted, you can cross check colours.

I would put in a few extra fuses but doing this deviates from the wiring diagram, so unless you are confident that may be a step too far.

I also suggest having a soldering iron and some spade ends/bullet ends/crimp tool available because it is unlikely that it will go "plug and play"

Finally give very careful thought to how you are going to test and power up!

Graeme Williams

But if it had a new loom 5 years ago, then 'why' ?
davidsmith

My blog might be helpful:

http://1965mgmidgetrestoration.blogspot.co.uk/2012/11/wiring-expeditions.html

But no guarantees though!!
James Paul

If you want to test your circuits without letting the power smoke out, use a 6 volt lantern battery connected to the battery cables. You'll get the power to use your test probe but not the amps. Much more forgiving than your 12 volt battery.

If I was going to muck about under my dash, I'd pull the steering wheel and the seats. Give me more room inside bit to lay on my back, also as has been said, if it got a new loom in 2012, why the need to change it?

Cheers,
Clare
Clare Ravenwood

Many thanks everybody for your comments. Unfortunately, I had a short last month such that part of existing loom has disintegrated, hence the need to replace it. I have found the cause for this so I don't foresee this being an issue once the new loom is in place.
I think I'll plump for dash in, wheel off in the first instance and I'll see how I get on.
Many thanks again.
J Fettiplace

James, I was too afraid of just getting it wrong, so I rang out every wire from end to end, and labelled them. Mine was a MkII Sprite with negative earth and alternator, and looked like this (people with long memories will remember my shame).

Nick and Cherry Scoop

There used to be a supplier that made looks with labels on every connector. But it's not a bad idea to label up the loom with masking tape tabs with it laid out on the sitting room carpet, and following the handbook wiring diagram.
GuyW

James

While you are rewiring it is worth checking and cleaning all earthing points, plus making sure the existing components you are connecting the new loom to have clean and tight connections.

Do not be surprised if new things do not work on first connection, either due to poor connections or earths, or has happened to me that the old loom and components connected to it worked in mysterious ways! (I.e. was supplied by strange non-standard supply or earthing routes - some not intentionally wired up!)

Clare's idea of a using a large torch (Ever Ready lantern) 6v battery is a useful tip.

Good luck

Cheers
Mike
M Wood

Yes, the sitting room carpet is the place.
Nick and Cherry Scoop

Nick: I went to the same trouble but actually used white insulating tape on each cable end and marked it with a pen. Being colourblind didn't help.

Regarding earths, IIRC the new loom provided all the earths through its cabling so as a matter of course they were all remade.

Graeme Williams

That would have been sensible, Graeme, but everything has to be graphic for me. Even my lists have to be drawn - and possibly coloured in.
Nick and Cherry Scoop

Nick, your fully illustrated weekly supermarket shopping list must truly be a work of art!
GuyW

Alarm engineers use white insulation tape and a marker pen, apparently.


I have heard of using a battery charger as a power source, as it should trip if there is a short.
Dave O'Neill 2

Laura makes the shopping lists. Morrisons doesn't inspire me.
Nick and Cherry Scoop

This thread was discussed between 27/03/2017 and 29/03/2017

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