Heater wiring

[trmorrisminor]

Good evening, I am in the process of restoring a 1971 morris minor van, l had a new wiring loom fitted a couple of years ago by a chap, but the heater was never fitted into the wiring loom as he said there were no spare places on the loom to attach it? My spare time is very limited as I have a very young family. I am hoping to have a few hours on the van in the next few weeks ( which is based over at my dads house) . So that I have gone prepared (I hope to wire the heater in, I haven't got the heater to hand as its with the van) but how many wires does the heater have coming out of it, from memory its 2 but I honestly cant remember, am assuming black cable to earth on the body as car is negative earth and the green to live. I have looked at a picture of a heater for sale on ebay but the wiring is not that clear, if anybody can help I would be very grateful.

[geoberni]

l had a new wiring loom fitted a couple of years ago by a chap, but the heater was never fitted into the wiring loom as he said there were no spare places on the loom to attach it?

That seems a bit strange.....

Items 18 & 19 ....identified as Heater Switch and Heater (when fitted)
The Green is picked up from a junction with items 25 & 26, identified as Oil Filter Warning Light/Switch (when fitted) and Oil Pressure Warning Light/Switch.
Item 15, upstream of the supply line, is the Instrument Voltage Stabiliser.

Moggie Wiring.JPG (83.42 KiB) Viewed 1389 times

[trmorrisminor]

Thats kind of you to reply with the wiring diagram thankyou, will have a look when i am at dads and will try and see what he has done, failing that i plan just to take a live straight to the fuse box and negative off the chassis. Am i right in thinking the heater has only two wires coning from it, a black and a green? Green being live and black being negative?
Many thanks

[geoberni]

Well that's what's shown on the diagram and I can think of nothing else that would be required.
I can't comment 100% because my heater is an after-market item since I've a SII.

[Mark Wilson]

I can't remember exactly, but I think the green/yellow heater feed should have a spade connector and should clip directly to the voltage regulator incoming terminal on the back of the speedo. As it is so close to the heater I don't think there would be any separate provision in the loom. The black wire should have a bullet connector and connect to any of the black earthing wires on the loom.

[trmorrisminor]

Many thanks for all your help, have managed to dig out an old speedo which was removed from a scrap car which still has all the wires attached. Cannot see on this speedo a yellow and green lead attached to the voltage regulator? It looks like there are 3 green wire connections on it, one has two green wires on it into one spade terminal, one has one green wire coming from it, and then one has a green wire onto it which then connects onto the fuel gauge, which leaves one spare terminal, is this what the heater connects to? Thankyou to everyone for there help. Explains why the guy that fitted the new loom couldn't find a terminal to connect the heater too if it should be connected to the back of the voltage regulator? Picture to follow in next box

[trmorrisminor]

Enclosed photo

[Sleeper]

Do not connect the heater to the Voltage stabiliser , Lucas smoke will be the result.
Which heater do you have , round or square?

John ;-)

[trmorrisminor]

Hi John, i have the late heater and its a late van. 1971.
Many thanks Richard

[trmorrisminor]

John , i should have said its the late square one.
R

[geoberni]

First thing, I have no idea why Mark Wilson threw in Green/Yellow.
Look at the diagram it is G for Green.
GY is the colours for items 25 & 26 switches, after their respective warning lamps.

Second thing, while Sleeper is correct that connecting the heater to the OUTPUT of the Voltage Stabiliser is a ridiculous idea, that IS NOT what we're talking about. The Output of the VS is only for the Fuel gauge, simple as that.

Again LOOK AT THE DIAGRAM.

It is simply using the connection onto the VS as a pick off for other circuits.
It is that one with the 3 Greens on it!
Look at your photo, the LG output of the VS goes to the Fuel Gauge and then the GB goes off to the Tank Unit.

What you have there is exactly what it required.

While I don't have personal experience of later model cars, I see no reason to doubt the accuracy of the Wiring Diagram or its stated colours. I see no relevance to what heater is fitted, Round, Square, BMC or after market, it's only a supply and earth.

VS Temp.JPG (68.93 KiB) Viewed 1312 times

[Sleeper]

If you had the round one, there is a rheostat in circuit, as you have the later square one, there is only a switch ( if the diagram is to be believed ), the live supply should be around, it's one of the green wires from the B terminal on the voltage stabiliser , the spare terminal " I " looks tempting but NO , maybe the green wire is floating around in the ether near the heater , you could trace it from the V. stabiliser.

The only other connection needed is an earth , most probably a black wire ( or you could use any earth point . ). If I remember correctly there should be a couple of bullet connectors in circuit for the heater...

John ;-)

[geoberni]

John
Is is not standard that the Rheostat on the round one is integral to the Heater 'assembly', thus still only 2 wires? This example has a White instead of Green.

Heater.JPG (118 KiB) Viewed 1306 times

In my case, as it's an after-market Tudor model, I have a separate dash mounted Rheostat, but I wasn't going to mention that and confuse Richard further.

[geoberni]

A bit of a tangent this, but worth pointing out.

( if the diagram is to be believed ),

John ;-)

Now if you're looking for an incorrect diagram the place to look is the Printed version of the manual as now available. it has an error that is not on the pdf version I have, yet they are supposedly the same 'final version' 14th Edition, of the original manual.
It relates to N38 and the accompanying item list on N39 intended for the pre '63 Indicator equipped cars.

The Voltage Stabiliser wasn't yet fitted, but in the printed one I have, someone added it to the list of components thus making items 13 - 16 incorrectly identified.

These are from the pdf of the genuine 14th Edition manual

Another diag.JPG (37.18 KiB) Viewed 1296 times

Another one.JPG (13.15 KiB) Viewed 1296 times

But in the modern hard copy I have published by Brookland Books, the table reads.....

20210125_111301.jpg (544.67 KiB) Viewed 1296 times

[Mark Wilson]

I referred to the green & yellow wire because that is the colour of that wire on my car. I'd forgotten, however, that I had cannibalised a twin fan version of the heater from a mini, which is fitted with green & yellow. The original heater feed was indeed green.

Connecting to the voltage regulator INCOMING feed, which is what I said, will NOT cause any smoke!

[trmorrisminor]

Many thanks for all your comments, So is the general consensus that the voltage reg is where I should connect the heater live green wire to or would it be better that I extend the live green heater wire and feed it directly to the fuse box and earth the black wire to the car bodywork?
Many thanks

[geoberni]

Well why make more work for yourself, including adding yet another connection to the fuse box?
Just put it where it's supposed to be, with the other 2 green wires on the Voltage Stabiliser.
Just make sure you put it on the correct terminal.
From the photo you posted above, the old Speedo you had has got a double wire spade fitting and a single one.
It will depend on which one is 'missing' from behind your actual speedo. That's going to be the tricky part.
If you've got 2 single spade terminals connected there, you're going to have to get a piggy back terminal or twist 2 cables together and then fit a new spade crimp to the twisted pair.
https://www.cablecraft.co.uk/fully-insu ... -terminals

It just depends what you find on your Speedo.
As you mentioned originally about a 'new loom' being fitted, I'd make an educated guess that you'll find 2 single wire spade connections occupying both lugs for the B connection.

As you have that old Speedo with the double cable terminal, if needed, I would consider reusing that. Just use a couple of Butt Splice inline crimps to fit it to your wiring.

[mogbob]

A piccie from ESM's website shows the B terminal ( Battery ) referred to by geoberni and the output terminal I ( Instrument )

https://www.morrisminorspares.com/searc ... fscr892602
Bob

[kevin s]

The minor only has 2 fuses one for green ignition fed circuits and one purple for permanently live circuits and when I stripped our 1970 loom they all seemed the same gauge, so really any convenient connection to a green wire and a good earth will work, our earth was connected to an eye under one of the heater to bulkhead nuts.

Kevin

[trmorrisminor]

Many thanks for all of your inputs and help, much appreciated. When i go over to dads i will have a look and see what terminals are free on the back of the voltage regulator.
Thankyou.