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MG Midget and Sprite Technical - Frogeye/Mk1 Midget Power to Loom

Can anyone tell me (or provide a photo) of how battery power is fed to the wiring loom on the early cars? The loom is all fitted under the bonnet but still to fit the dash. I've just fitted the battery (not connected!) and have realised that as I have it at the moment there will be no power to the loom!

There is of course the large feed from the Dynamo but that will only supply power to the control box when the engine is running.

The only thing I can see that looks like it should go somewhere major is a part of the loom currently under the dash. It's got one large brown wire and one small red and white wire. According to the wiring diagram brown should be the main feed and goes from the battery to the control box. I can only see red and white for the dash lights but both these wires are in a covered 'branch' off the loom and are long enough to go back through the bulkhead and reach the starter switch. So am I right in saying that the large brown wire should connect to the battery side of the starter switch? But then where does the dash light part come in to it?!

Also, on a lot of the photos I've seen of that area there only seems to be the oil and water gauge lines coming through the bulkhead at that point.

I've still got the old loom so I'll have a look to see if that sheds any light. I hope I ordered the right replacement loom!!

Thanks in advance!
John Payne

Here is the switch and battery area:




John Payne

There should be a brown cable with a circular terminal connector which attaches to the cable which feeds the starter switch. If you still have the starter cable the terminal that goes on the battery pole may have a hole in the side of it. Originally This was to accommodate a tapered lead connector which connected to the brown main cable. On the new looms this tapered lead connector is omitted. This usually means you have to use a bolted clamp on the battery.
Bob Beaumont

Is it definitely a red/white wire, not white/red?
Dave O'Neill 2

Mmm, yes sorry I think it's mostly white with red.

Had a look at the old loom and there is just a single brown wire in that area with no terminal.

Just to clarify, the car wasn't complete when I got it so I'm a bit in the dark in some areas!

I see what you are saying Bob, I might have to make something up. The large brown wire has a big female spade on it so maybe I need to replace that with a bolt on type. It's the fact that it's in a long cloth covered branch with the white and red wire that confuses me more.

I'll have another look tomorrow and maybe take a photo of the branch off the main loom.

I'm dreading getting to the point when I connect the battery in case my new loom goes up in smoke!
John Payne

It sounds like you have a loom for a later car.

Cars with a solenoid, rather than a pull starter, would have a large spade terminal for the brown wire and the white red comes from the ignition switch and energises the solenoid for starting.
Dave O'Neill 2

John

MKI Sprite wiring diagram is in the Driver's Manual and the Workshop Manual. Copy here: http://www.gerardsgarage.com/Garage/Tech/WiringDiagrams/buegeywiringWS2.htm

It is a bit late to mention this, but you can buy the correct loom direct from Autosparks (including any mods you may want): https://www.autosparks.co.uk

Thanks
Mike
M Wood

Dave's right you may have the wrong loom. The Mk11 sprite loom is slightly different to the frogeye eg the regulator is in a different place and the terminal connectors are spades rather than screw in.

Bob Beaumont

Update time. The loom I have is (according to my receipt) for a GAN2 midget which is right as I wanted to have an electronic tach instead of the mechanical one. My car is/was a GAN1 but now is more GAN2 and with a 1275.

So I am wondering if some parts of the loom are kept the same to save having two types. The part numbers are different though.

It also doesn't help that I've been looking at the wrong wiring diagram in the Haynes manual!

So I reckon I'll have to use the big brown cable but go to the battery with it and just omit the White/red.

I've found this photo showing what I guess is the original type of cable to the battery that Bob describes:



John Payne

Hi john

yes that looks right. the brown cable with the yellow tag goes straight to the battery. The white red comes from the ignition switch and I suppose is redundant. The loom for a GAN1 would not have had the white red i assume.

Bob
Bob Beaumont

John,

1) The big brown wire is definitely the one which should go straight to the battery. It is (or it should be) the largest diameter wire in the loom because it must carry all the current from the battery/generator. The SIZE of the wire is the clue.

2) The early HAN6/7 and GAN1/2 looms never had a white / red trace wire because they never had a starter solenoid switch. So you either have the wrong loom or you have a 'generic' loom suitable for more than one model. You probably (?) also have the extra white wire for the later SU fuel pump.

3) You are right to be worried about short circuits when you first connect the battery - but if you connect a little 12V bulb between the battery and the big brown wire before you connect-up for the first time, you will avoid all possible disasters. With everything switched off, the bulb should not light when you first connect the wire. If the bulb lights, start investigating why. Alternatively, an ammeter with an in-line fuse is a good idea - particularly when you switch ignition on for the first time and
start trying each circuit in turn. When you DO switch
ignition on for the 1st time, I recommend disconnecting the coil - a tiny current should still
flow to the fuel gauge, but that should be it. Then
connect the coil and make sure the current flowing is correct. Etc. etc. OK?

4) No matter what, you should avoid tightening all
connections to the battery and then switching on for the 1st time. That's when the horrors can start because, by the time you have disconnected things, wires will have melted and the loom may have burst into flames.

Good luck with it all,
John.
J.E. Davies

I'm not sure of the detail of the pull start cars but your starter switch looks to be in the same place as the solenoid on later cars. The big brown lead could therefore go to the battery side of this switch couldn't it? - rather than direct to the battery - this could possibly be tidier as the brown lead will be in the looms "designed" location
S G Macfarlane

J.E. Davies

The factory put the brown wire direct to the battery, it's not long enough to reach the starter switch.
J.E. Davies

John, I think the assumption is that as the loom has a white/red wire as well, it is either a generic or a MK2 loom, in which case the brown will be long enough!
GuyW

yes - I was assuming the car has a loom designed for a solenoid
S G Macfarlane

Thanks for the help. No solenoid, just a pull switch. I had thought that I'd connect it similarly to the solenoid type but I think now I'll do it as it should be. I'll probably hide the extra branch off the loom behind the dash and connect a new cable to it.

John, thanks very much for the tips on connecting up for the first time. I'll definitely use the bulb method. I think I'll also put a small inline fuse in the loom to battery cable initially, then maybe beef it up later and keep it as a failsafe. All behind the dash of course. It's been a while since we were in touch when I first bought the car, it's coming on now and may even see the road later this year! It's not perfect (or anywhere near correct for the year) but I think it should look pretty good for a home restoration.

I'm hoping to fire it up for the first time in the next couple of weeks which will be a major step - I might have a break from it after that!




John Payne

John

MkII Sprite Wiring Diagram for reference. This is from the manufacturer's AH Sprite Workshop Manual AK1834.

Cheers
Mike


M Wood

Same wiring diagram for MkII Sprite in the Austin Healey MkI & II Driver's Handbook (AKD1627B)


You know, Nigel may be on to somethin g about the usefulness of such handbooks!
Cheers
Mike


M Wood

Wiring diagram for MkI Sprite for comparison.

(source as before: the Austin Healey MkI & II Driver's Handbook, AKD1627B).

Cheers
Mike


M Wood

It would help if I uploaded the correct scan for the MkII Sprite from the Driver's Handbook - sorry.

MkII Sprite wiring diagram in the Austin Healey MkI & II Driver's Handbook (AKD1627B).

Note the scan in my earlier posting from the Workshop Manual is for the MkII Sprite.

Cheers
Mike


M Wood

Thanks for that Mike - would you believe I've got 3 of those drivers manuals for the Mk2 Sprite/Mk1 Midget! I hadn't a clue they had a wiring diagram in there. Will come in very handy tomorrow when I start connecting up behind the dash.

In fact I'll go and get one now and see if there is anything else in there I might find useful!

Cheers
John Payne

This thread was discussed between 18/05/2019 and 27/05/2019

MG Midget and Sprite Technical index

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