Kevlcat

Member
Hi all,

I am just going through the rewiring of my 72 S3 petrol, using a nice new auto sparks harness. At the weekend I started to sort out all the ignition switch & instrument panel....previously carefully labelling everything etc.
As part of the resto, I decided to just renew the ign switch. Below is what came off.....
00EC6081-80B9-49B5-B0E9-3F9DA911FC73.png
After some research, I believe this to be a late S3/90 switch...part no PRC8230?
The wiring was as follows.....t1=white/red, t2=brown, t3=white, t5=nowt

Based on the parts book, I ordered switch 579085 (157sa) photo as below....
21C0F168-98F5-4C06-99B8-C9F38FBFEC84.jpeg

I duly wired up per green bible wiring diagram......t1=brown (only one spade connector, which is odd as wiring diagram shows multiple browns to this terminal...ie horn).....t2=white, t3=white/red, t5=nowt

All wiring checked and double checked, earths good etc.....ignition on.......no charge light or oil pressure light, turn key to fire up.....engine would fire, charge flickers, but as soon as let go key.....no more spark to coil.....plus some other weirdness.....

so I put back the original (white insulated) switch and wired back up as it came off a year ago.....all working perfectly?
This morning I tried the new switch again (brown insulation), but this time after some experimenting...t1=nowt, t2=white, t3=white/red, t5=brown......and it all fired up perfectly and the charge light, oil pressure light behaved as they should.....

so in summary.....is the new switch faulty.....ie terminals marked with incorrect nos or is wiring diagram in green bible wrong?....

Am I going mad...am I missing something here?
 
I've bought 'new' ignition switches before that are incorrectly marked. As you did I wired it up as per the book and got nothing, it was just trial and error to get it working correctly. I just put it down to a rogue 'Friday' switch but it might just be that all copies are badly assembled/marked.
 
you were putting the 12v bat feed into the starter solenoid feed from the wrong end,so to speak,hence when turned(springy) you were feeding the ignition coil etc
1=red white TO solenoid,2 =brown always live etc,
i have fitted inline fuses everywhere except coil/starter and always carry an extinguisher,
atb and good luck
 

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