Series 2 Ignition Wiring problem, car wont start !

[Nickleback]

So my steering lock now works corrrectly, all steering column and ignition switch wiring put back as before (from my notes) and now the car wont fire up
Ignition lights all work, starter turns it over but it does not fire on any cylinder at all ?
Re-checked wiring on ignition switch and found that the way it was wired does not correspond with S2 wiring diagram, I have the four correct colour coded wires to use but the order varies ?
Here's a view of the back of my Lucas 157SA switch:


When I took it out is was wired:
1) White/Yellow
2A) Brown
2B) Brown
3A) White
3B) -
5A) -
5B) -

Wiring diagram says:
1) 2 x Brown (but it is only a single spade connector on the switch)
2) White
3) White/Yellow
4) -

Not only does the diagram not have the same numbers as the switch but the tags and connection are in a different order ?
So what is the correct wiring for this switch ?

[Gfhug]

Mike, without removing my switch I can't fully compare. But one thing I found is that mine had been wired incorrectly and you may need to do some checking of what gets connected with each switch position.
This is because the main supply to fuses 6 and 7 is isolated on starter engagement to provide max power to the coil and fuel pump. Also the slightly later S2 is set up with the ballast resistor, I think Chris Vine's blog has a good write up of that.

Check out your switch and see if you have the power going to the correct parts.
Mine shows different tag numbers with tag 15 going to the coil and fuel pump. Tag R goes to fuse 6 (isolated at start position). Tag 50 is the white/yellow to starter solenoid relay tag W1. Tag 30 is the brown from battery terminal post and the brown to starter solenoid relay tag C1.

I hope this will help

Geoff

[mgcjag]

Hi Mike...have a look at this diagram from the knowledge base for a S2 it has the standard ign sw and above the wireing if you have a steering lock.....https://dl.dropboxusercontent.com/u/849 ... Colour.jpg

If the switch is the original one you started with and you havent changed any wireing then if you replace as you took it off then it should work the same...you may just have a bad joint somewhere.....if all works but dosnt fire then sounds like no live going to the coil......

[christopher storey]

With S2 it also needs to be remembered that the entire ignition circuit goes through the white wire which goes through the tachometer. If for any reason you have taken the tacho out of circuit e.g by disconnecting the plug with the white wire on it, you will have no volts to the ignition system

In connection with that I also wondered whether you may have taken the white wire from one of the fuses that is isolated when the starter switch is operated , which would have the same effect except that the engine might just fire on release of the starter switch

[Nickleback]

Hi Mike...have a look at this diagram from the knowledge base for a S2 it has the standard ign sw and above the wireing if you have a steering lock.....https://dl.dropboxusercontent.com/u/849 ... Colour.jpg

Steve,
That's the diagram I've already been working with which shows the differences that I don't understand as I'm sure I put it all back correctly but like you I think no coil feed, so I will check to see if I have a spark at the plugs ?

Chris
I have checked the connections above the ignition switch below the back of the tacho and found a cable with a 3 pin female spade plastic head connector disconnected but cant see where it goes ? Hopefully you can see it in the pic, it has 2 single white cables and 1 green one going into the back of it


Geoff,
I've just checked the diagram again and found a 3rd ignition switch layout over to the top left for the diagram specifically for the Britax switch with steering lock (dont ask how I missed it ! ) which lists connector 30 = N feeds, connector 15/54 for the W feed & connector 50 for the WY feed so I need to figure out how that relates to the terminal markings on the actual switch of 1,2,3 & 5 ?

Thanks guys

[mgcjag]

Hi Mike as Christopher said the plug you show 2 whites and a green are for the rev counter, you need to plug it in....find the other end or you have no ignition to the coil

[christopher storey]

Mike : I think that's your answer. That plastic plug goes to a corresponding 3 way connector on the back of the tacho. The position does perhaps vary according to date of the instrument but if you feel round the back of it you should be able to identify it - it will have 3 male spades on it

[Nickleback]

Thanks Chris,
I have "fished around" behind and can feel nothing that would be the correponding plug on the back of the rev counter & I was really trying to avoid de-installing it and the cable to get a good look, do you happen to have a picture of the back of one ?
When I was removing the harduras there originally, a 2" single white cable with male connectors fell out, could it be that this plug had been looped white to white with this to make a connection & that my rev counter works fine without this plug in it as I cannot fine an apperture on the rev counter for it ?

[christopher storey]

Well, there are two types of these early electronic tachos ( RVI on the front face ) before they changed to the voltage sensing types ( RVC on the front face). The earliest had the sensing loops of white wire externally wound on the back of the tacho . The second type was the type your wiring is for, with the sensing loop internal to and integral with the tacho circuit board . I'll see if I can find pics of the two types, but it is unlikely that you would not be able to feel if you had got the external loop type, which would of course not be compatible with your wiring. What you can do temporarily if you don't want to take the tacho out is to bridge the two white wires on the female plug shown in your photo, which should at least restore 12v to the LT side of your ignition

Just in case there has been a horrible pick and mix operation on your car , I suppose we are right in thinking that your car does not have the camshaft generator driven type tacho fitted to the S1 cars ?

[PeterCrespin]

Thanks Chris,
I have "fished around" behind and can feel nothing that would be the correponding plug on the back of the rev counter & I was really trying to avoid de-installing it and the cable to get a good look...

'De-installing" - is that a bit like 'removing'? Have you been drinking Mike? In Canada they have a punishment for drinking...

[Nickleback]

Lol, yup sure is, too many years back in the 80/90's spent taking customers HF phone car kits in and out of car's as fleets were changed so often back then !
One of the large London based banks changed their directors Jaguar sovereign's every 6 months and each one had a twin handset install one inside each custom made arm rest in matching leather
I could think of worse music to listen to when drunk

[Nickleback]

Well, there are two types of these early electronic tachos ( RVI on the front face ) before they changed to the voltage sensing types ( RVC on the front face)

Thanks Chris,

Ok, my problem was that my rev counter does not have RVI or RVC marked on the face but was fresh from a Speedograph rebuild only 6 months ago, so I knew it worked just fine.
So, I decided to use the white loop cable on the 3 way connection from white to white and put the ignition wiring back to as in my notes as I had removed it.
And.......................................she started up first time and the rev counter works fine !!

So really my only question left is should the green wire in the 3 way connector be needed / connected to anything ? The wiring diagram shows that it goes to from one side of fuse 7 to the rev counter, but what does it do ?

[politeperson]

Just a quick thought.

I had the same problem about 4 months ago.

From memory, I looked at the wiring disgram and figured out the ignition supply did not come from the battery but went through 2 relays first.

Turns out one of the wires had dropped off one of the pair of relays, that is screwed into the back of the left hand front mudguard. Picture attached.

I have also dispensed with the ballast resistor circuit in the box on the bulkhead on the right hand side, as I have a boosted 123-tune ignition.

Only take you a second to check?

20161201_181400_13.jpg (104.84 KiB) Viewed 17803 times

[juicerider]

Hi nickelback
I had a problem starting mine when I got it. The engine would only fire when the ignition switch was released, as the PO had the connections in the wrong order at the back of the ignition switch. The ignition switch was cutting power to the distributor when the starter was engaged. Mine is an early S2 so if your is the same this might help.
I can't remember the position of each wire on the back of the ignition switch, and mine had no numbers anyway, however it's easy to figure out where they go with a multimeter.
Here is how I figured it out, and it might help to check yours is connected rite.
The conector with only one terminal on the switch terminal for the starter relay.
Remove the other wires from the back of the switch and with a multimeter check the other 3 terminals on the back of the ignition switch are all connected up when switch is in the run position. When the key is moved to start, one of the 3 terminals should be isolated. This is where the radio is concerned to. This now leaves 2 terminals to identify. When the key is turned backwards past the off position the only terminals that should have an electrical connection between them is the radio and the battery. This should help you identify there the battery terminal is. Connect both brown wires to this one. One should have +12 volts all the time. The other brown wire is the + to the starter relay. The last terminal on the back of the ignition switch connect the white wire to, this should go to fuse 6 and 7. As a Check make sure the terminal to fuse 6 does not lose power when the starter is operated as the power to the tachometer and distributer come from fuse 6 and 7
Hope this helps
Steve

[christopher storey]

Mike : it sounds to me as though Speedograph have converted your tacho to the later RVC ( voltage sensing ) type in which case your green wire is redundant . The purpose of the green wire with the earlier types ( RVI ) is solely to power the moving coil which drives the needle, and this is not needed with the later types

[Nickleback]

Chris,
Thanks for the confirmation that the green wire is no longer needed, saved me stripping the whole lot out looking for a plug that did not exist !

Steve,
At last a way to make sense and check all the ignition switch wiring is correct and no one has been previously meddling or modifying,

Politeperson,
Just checked, yup all in place

[mark10337]

With S2 it also needs to be remembered that the entire ignition circuit goes through the white wire which goes through the tachometer. If for any reason you have taken the tacho out of circuit e.g by disconnecting the plug with the white wire on it, you will have no volts to the ignition system

In connection with that I also wondered whether you may have taken the white wire from one of the fuses that is isolated when the starter switch is operated , which would have the same effect except that the engine might just fire on release of the starter switch

Chris

Which white wire should be isolated when the starter switch is operated. I am having a few issues myself at the moment in this area.
No 12v at the coil. Green and white wire at the tacho have voltage coming in. Nothing going out. I was also wondering if it is an earthing problem on the tacho.

[Hugo]

Having just stumbled across this post, can I take you right back to the beginning? That picture of your ign switch is a bit troubling - it looks as though that rivet at the top has got hot at some point, and maybe also the one at the bottom right. This is suggestive of a bad connection within the switch, and when these get hot they tend to soften any springs that may be in the vicinity, making the problem even worse. Then you can end up with intermittent faults and annoying things like that. Just a thought.

[christopher storey]

Mark : I'm not really sure , on reflection, what I meant by that ( white wires being isolated during starter operation ) , except that someone else had referred to it , and if someone had miswired it so that isolation happened when the starter switch was operated , it would explain those instances where the engine only fired when the starter switch was released .

In your case, what I can say definitely is that

i. with the ignition on there should be 12v at the white wire on the tacho AND at the coil

ii. when the starter is operated there should still be 12v at the white wire on the tacho AND at the coil

iii.there should never be a situation where there is 12v coming IN to the tacho , but 0v on the output side of the white wire

If yours is one where the white wire is doubly looped on the outside of the tacho, then the only two ways you could get 12v at the tacho but 0v at the coil are

iv.if the wire is broken somewhere inside the insulation either at the tacho loop or in the white wire between 3 way plug and coil - unusual but not unheard of .... or perhaps more likely

v.a fault in the 3 way plug which connects the white wires ( in and out ) to the loop on the back of the tacho, and the green wire from the fuse , to the green wire going into the tacho

If, however, your tacho is the later type with the sensing coil being internal i.e. within the case , then there are more possibilities for some disconnection having occurred , thus resulting in situation iii. above arising


Finally, I should say that a failure to earth the tacho body might well result in the tacho not displaying, but it would not interfere with the supply to the coil at all

[mark10337]

Thanks Chris.

The error typically is that the ignition -> fuse 6 is wired onto terminal 4 instead of terminal 2 (depending which ignition lock one has). The ignition switch cuts out terminal 4 on starting and connects again when returned to on.

There were a number of changes in the late 69 / 70 models on the ignition system etc. I have one of the early ones.

Fuse 7 ----> white ----> tacho connector
Fuse 6 ----> Green ----> tacho connector
tacho connector ----> white ----> + ignition coil

To do some diagnostics I rigged up a test lamp to the + on the coil. Quite nice to have a light centre engine at the front! I found one of the earth leads behind the tacho on the bulkhead had come loose, so that was reattached.

As you need the tacho connected in place to connect the two white wires, I had always assumed there may be something going on inside the tacho to do that. After a little fiddling, I am coming to the conclusion the tacho connector isn't making a good enough connection, or it is inside the tacho itself.

Now I can get it to start, but I am still seeing that 'sometimes' after starting, I turn off. Turn on again, and there is no 12v at the coil until I turn to start at which point it is fine again. Perhaps time for a tacho overhaul.

Hopefully enough to drive back to Switzerland tonight though in -10 degrees!